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StaticHandler disclosure of classpath resources on Windows when mounted on a wildcard route

Low
vietj published GHSA-53jx-vvf9-4x38 Feb 9, 2023

Package

maven io.vertx:vertx-web (Maven)

Affected versions

Any 4 version below 4.3.8

Patched versions

4.3.8 and above

Description

Summary

When running vertx web applications that serve files using StaticHandler on Windows Operating Systems and Windows File Systems, if the mount point is a wildcard (*) then an attacker can exfiltrate any class path resource.

Details

When computing the relative path to locate the resource, in case of wildcards, the code:

vertx-web/vertx-web/src/main/java/io/vertx/ext/web/impl/Utils.java

Line 83 in 62c0d66

return "/" + rest;

returns the user input (without validation) as the segment to lookup. Even though checks are performed to avoid escaping the sandbox, given that the input was not sanitized \ are not properly handled and an attacker can build a path that is valid within the classpath.

PoC

https://github.com/adrien-aubert-drovio/vertx-statichandler-windows-traversal-path-vulnerability

Impact

Medium - Low, given that Windows as a deployment platform is not the common and the access is locked to the classpath (which means local app resources).

Severity

Low

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:N

CVE ID

CVE-2023-24815

Weaknesses

No CWEs

Credits