ucutils - Unicorn Emulator Utilities

ucutils provides helper utilities and abstractions for working with the Unicorn CPU emulator. It simplifies memory management, register access, and architecture-specific operations while supporting both x86 and x64 architectures. The library also includes Windows-specific utilities for emulating Windows structures and behaviors.

For more comprehensive Windows emulation including API hooking and system call emulation, consider using the Speakeasy project. ucutils focuses on providing low-level CPU emulation utilities rather than full system emulation.

Create the extended emulator instance:

emu = ucutils.emu.Emulator(unicorn.UC_ARCH_X86, unicorn.UC_MODE_64)

Map and access memory (typical Unicorn API):

emu.mem_map(0x0, 0x1000)
code = b"\x48\xC7\xC0\x01\x00\x00\x00"  # mov rax, 0x1
emu.mem_write(0x0, code)
emu.emu_start(0x0, len(code))

Easily access registers:

assert emu.rax == 0x1

And, easily allocate and access memory:

addr = emu.mem.alloc(0x1000)
emu.mem_write(addr, b"AAAA")
assert emu.mem[addr:addr+4] == b"AAAA"

Stack operations:

emu.push(0xAA)
assert emu.pop() == 0xAA

Emulation stepping:

emu.mem_map(0x0, 0x1000)
code = b"\x48\xC7\xC0\x01\x00\x00\x00\x48\xC7\xC3\x02\x00\x00\x00"  # mov rax,0x1; mov rbx,0x2
emu.mem_write(0x0, code)
emu.stepi()  # Execute first instruction
assert emu.pc == 0x7
assert emu.rax == 0x1

Checkpointing:

assert emu.rax == 0x0
assert emu.rbx == 0x0

with ucutils.checkpoint.checkpoint(emu):
    emu.rax = 0x1
    emu.rbx = 0x2

    emu.stepi()

    # changes will be reverted after the block,
    # including memory contents and registry context.

assert emu.rax == 0x0
assert emu.rbx == 0x0

Install TEB and PEB for Windows process emulation (useful for tracing shellcode), and then load a PE file:

ucutils.plat.win64.map_teb(emu)

pe = pefile.PE(data=b"MZ...")
ucutils.plat.win.load_dll(emu, {"filename": "payload.dll", "pe": pe})

# exports are added to emu.symbols
assert "payload.dll!ServiceMain" in emu.symbols

# LDR_ENTRY is registered in emulated memory,
# which is useful for (shellcode) payloads that manually resolve imports.