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Unico

Unicorn PE function runner

Installation

At first, install Unicorn Engine. Then, install required PyPI packages by pip install -r requirements.txt.

Usage

$ python unico.py
Usage: python unico.py PE_FILE [ADDR_START ADDR_END]

If ADDR_START is omitted, it starts from AddressOfEntryPoint. If ADDR_END is omitted, it tries to exit when the function returns. To get the better result, you need to narrow the emuration range.

Dump and diff the memory states

Unico outputs the below 4 files.

  • pe_image_{before,after}.dump: memory state of PE image range at the beginning/end of the emuration
  • pe_image.diff: diff of above
  • stack.dump: memory state of stack range at the end of the emuration

Also, it outputs the register values to stdout at the end of the emuration.

Trace memory accesses and IAT calls

The example below traces IAT calls and examines memory WRITEs to sockaddr struct specified as the 2nd argument of connect().

$ python unico.py Release.exe >trace.log

$ grep IAT trace.log
[0x2000004] IAT function is being CALL, GetSystemTimeAsFileTime(0x117f7ec, 0x0, 0x0, 0xdddddddd, 0xdddddddd, 0x0) = 0x1
[0x2000004] IAT function is being CALL, GetCurrentThreadId(0x117f7ec, 0x0, 0x0, 0xdddddddd, 0xdddddddd, 0x0) = 0x1
[0x2000004] IAT function is being CALL, GetCurrentProcessId(0x117f7ec, 0x0, 0x0, 0xdddddddd, 0xdddddddd, 0x0) = 0x1
[0x2000004] IAT function is being CALL, QueryPerformanceCounter(0x117f7e4, 0x117f7ec, 0x0, 0x0, 0xdddddddd, 0xdddddddd) = 0x1
[0x2000004] IAT function is being CALL, IsProcessorFeaturePresent(0xa, 0x0, 0xdddddddd, 0xdddddddd, 0xdddddddd, 0xdddddddd) = 0x1
[0x2000004] IAT function is being CALL, _initterm_e(0x402110, 0x40211c, 0x8, 0x117f7e4, 0x117f7ec, 0x0) = 0x0
[0x2000004] IAT function is being CALL, _initterm(0x402104, 0x40210c, 0x8, 0x117f7e4, 0x117f7ec, 0x0) = 0x1
[0x2000004] IAT function is being CALL, __p___argv(0x8, 0x117f7e4, 0x117f7ec, 0x0, 0x117f700, 0x0) = 0x1
[0x2000004] IAT function is being CALL, __p___argc(0x8, 0x117f7e4, 0x117f7ec, 0x0, 0x117f700, 0x0) = 0x1
[0x2000004] IAT function is being CALL, _get_initial_narrow_environment(0x8, 0x117f7e4, 0x117f7ec, 0x0, 0x117f700, 0x0) = 0x1
[0x2000004] IAT hook: memset 0x117d7a0 0x0 0x2000
[0x2000004] IAT function is being CALL, memset(0x117d7a0, 0x0, 0x2000, 0x1, 0xdddddddd, 0xdddddddd) = 0x117d7a0
[0x2000004] IAT function is being CALL, WSAStartup(0x202, 0x117d608, 0x1, 0xdddddddd, 0xdddddddd, 0x117d7a0) = 0x1
[0x2000004] IAT function is being CALL, WSASocketW(0x2, 0x1, 0x0, 0x0, 0x0, 0x0) = 0x1
[0x2000004] IAT hook: getaddrinfo 'www.example.com:http'
[0x2000004] IAT function is being CALL, getaddrinfo(0x402140, 0x402138, 0x0, 0x117d5fc, 0x2, 0x1) = 0x0
[0x2000004] IAT hook: socket connect '0.0.0.0:5889'
[0x2000004] IAT function is being CALL, WSAConnect(0x1, 0x0, 0x10, 0x0, 0x0, 0x0) = 0x0
[0x2000004] IAT hook: socket send 'GET / HTTP/1.0\r\nHost: www.example.com\r\n\r\n'
[0x2000004] IAT function is being CALL, WSASend(0x1, 0x117d600, 0x1, 0x0, 0x0, 0x0) = 0x0
[0x2000004] IAT function is being CALL, Sleep(0x3e8, 0x1, 0x117d600, 0x1, 0x0, 0x0) = 0x1
[0x2000004] IAT function is being CALL, WSARecv(0x1, 0x117d600, 0x1, 0x0, 0x117d79c, 0x0) = 0x1
[0x2000004] IAT function is being CALL, puts(0x117d7a0, 0x1, 0x117d600, 0x1, 0x0, 0x117d79c) = 0x1
[0x2000004] IAT function is being CALL, closesocket(0x1, 0x1, 0x117d600, 0x1, 0x0, 0x117d79c) = 0x1
[0x2000004] IAT function is being CALL, WSACleanup(0x1, 0x1, 0x117d600, 0x1, 0x0, 0x117d79c) = 0x1
[0x2000004] IAT hook: memset 0x117d7a0 0x0 0x2000
[0x2000004] IAT function is being CALL, memset(0x117d7a0, 0x0, 0x2000, 0x1, 0xdddddddd, 0x2000) = 0x117d7a0
[0x2000004] IAT function is being CALL, WSAStartup(0x202, 0x117d600, 0x1, 0xdddddddd, 0x2000, 0x117d7a0) = 0x1
[0x2000004] IAT function is being CALL, WSASocketW(0x2, 0x1, 0x0, 0x0, 0x0, 0x0) = 0x1
[0x2000004] IAT hook: gethostbyname 'www.example.com'
[0x2000004] IAT function is being CALL, gethostbyname(0x402140, 0x2, 0x1, 0x0, 0x0, 0x0) = 0x1
[0x2000004] IAT hook: htons 80
[0x2000004] IAT function is being CALL, htons(0x50, 0x402140, 0x2, 0x1, 0x0, 0x0) = 0x5000
[0x2000004] IAT hook: socket connect '0.0.0.0:80'
[0x2000004] IAT function is being CALL, connect(0x1, 0x117d790, 0x10, 0x50, 0x402140, 0x2) = 0x0
[0x2000004] IAT hook: socket send 'GET / HTTP/1.0\r\nHost: www.example.com\r\n\r\n'
[0x2000004] IAT function is being CALL, send(0x1, 0x117d7a0, 0x29, 0x0, 0x1, 0x117d790) = 0x29
[0x2000004] IAT function is being CALL, Sleep(0x3e8, 0x1, 0x117d7a0, 0x29, 0x0, 0x1) = 0x1
[0x2000004] IAT function is being CALL, recv(0x1, 0x117d7a0, 0x2000, 0x0, 0x3e8, 0x1) = 0x1
[0x2000004] IAT function is being CALL, puts(0x117d7a0, 0x1, 0x117d7a0, 0x2000, 0x0, 0x3e8) = 0x1
[0x2000004] IAT function is being CALL, closesocket(0x1, 0x1, 0x117d7a0, 0x2000, 0x0, 0x3e8) = 0x1
[0x2000004] IAT function is being CALL, WSACleanup(0x1, 0x1, 0x117d7a0, 0x2000, 0x0, 0x3e8) = 0x1
[0x2000004] IAT hook: inet_addr '192.168.0.1'
[0x2000004] IAT function is being CALL, inet_addr(0x40217c, 0x2180200, 0x117f7fc, 0x401507, 0x117f7, 0x117f7) = 0x100a8c0
[0x2000004] IAT function is being CALL, __acrt_iob_func(0x1, 0x1, 0x117f7f4, 0x0, 0x117f7b4, 0x401336) = 0x1
[0x2000004] IAT function is being CALL, __stdio_common_vfprintf(0x0, 0x0, 0x1, 0x402188, 0x0, 0x117f7a8) = 0x1
[0x2000004] IAT function is being CALL, GetModuleHandleW(0x0, 0x401511, 0x8, 0x117f7e4, 0x117f7ec, 0x0) = 0x400000
[0x2000004] IAT function is being CALL, exit(0x0, 0x8, 0x117f7e4, 0x117f7ec, 0x0, 0x117f700) = 0x1
[0x2000004] IAT function is being CALL, _cexit(0x0, 0x8, 0x117f7e4, 0x117f7ec, 0x0, 0x117f700) = 0x1

$ grep 0x117d79 trace.log
[0x40116c] Memory is being WRITE at 0x117d79c, data size = 4, data value = 0x0
[0x401176] Memory is being WRITE at 0x117d580, data size = 4, data value = 0x117d79c
[0x2000004] IAT function is being CALL, WSARecv(0x1, 0x117d600, 0x1, 0x0, 0x117d79c, 0x0) = 0x1
[0x2000004] IAT function is being CALL, puts(0x117d7a0, 0x1, 0x117d600, 0x1, 0x0, 0x117d79c) = 0x1
[0x2000004] IAT function is being CALL, closesocket(0x1, 0x1, 0x117d600, 0x1, 0x0, 0x117d79c) = 0x1
[0x2000004] IAT function is being CALL, WSACleanup(0x1, 0x1, 0x117d600, 0x1, 0x0, 0x117d79c) = 0x1
[0x40121e] Memory is being WRITE at 0x117d790, data size = 2, data value = 0x2
[0x401234] Memory is being WRITE at 0x117d794, data size = 4, data value = 0x0
[0x401240] Memory is being WRITE at 0x117d792, data size = 2, data value = 0x5000
[0x40124f] Memory is being WRITE at 0x117d5c8, data size = 4, data value = 0x117d790
[0x2000004] IAT function is being CALL, connect(0x1, 0x117d790, 0x10, 0x50, 0x402140, 0x2) = 0x0
[0x2000004] IAT function is being CALL, send(0x1, 0x117d7a0, 0x29, 0x0, 0x1, 0x117d790) = 0x29

Note that [0x2000004] IAT hook: socket connect '0.0.0.0:5889' is apparently wrong. By examining trace.log, you can find the below warning.

WARNING: memory is being WRITE to NULL page, it may cause inaccurate results from here.

[0x401c0e] Memory is being WRITE at 0x0, data size = 4, data value = 0x117f7ec

Add your own hooks

Unico has 3 types of hooks.

  • INIT hook, to initialize registers and memory state
    • call unico.add_init_hook(handler)
  • IAT hook, to emurate imported functions
    • call unico.add_iat_hook(name, handler)
    • The return value of hook function is handled as the one of hooked function
  • EIP hook, to change the state at some instruction addresses
    • call unico.add_eip_hook(address, handler)
    • The return value of hook function is handled as the new EIP value

For more details, read the code.

License

This project is a derivation from Unicorn Engine, thus released under the GPL license.

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Unicorn PE function runner

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