https://github.com/lunixbochs/patchkit

binary patching from Python
https://github.com/lunixbochs/patchkit

Last synced: about 1 month ago
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binary patching from Python

• Host: GitHub
• URL: https://github.com/lunixbochs/patchkit
• Owner: lunixbochs
• License: other
• Created: 2016-08-08T01:10:47.000Z (almost 8 years ago)
• Default Branch: master
• Last Pushed: 2023-07-06T02:12:21.000Z (12 months ago)
• Last Synced: 2024-05-02T00:12:55.768Z (about 2 months ago)
• Language: C
• Homepage:
• Size: 226 KB
• Stars: 623
• Watchers: 28
• Forks: 85
• Open Issues: 23
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
patchkit

----

Patches an ELF binary using one or more simple Python scripts.

Usage:

    patch   [patchdir|file...]

patchdir

----

Contains one or more Python patch files, which will be executed in alphabetical order against a binary.

Patch Examples

----

Nopping an address, injecting an assembly function, and hooking the entry point:

    def simple_patch(pt):

        # nop out a jump at the entry point

        pt.patch(pt.entry, hex='90' * 5)

        # inject assembly into the binary and return the address

        addr = pt.inject(asm='mov eax, 1; ret')

        # hook the entry point to make it call addr (ret will run the original entry point)

        pt.hook(pt.entry, addr)

Replacing a C function:

    def replace_free(pt):

        # pretend free() is at this address:

        old_free = 0x804fc4

        # inject a function to replace free()

        new_free = pt.inject(c=r'''

        void free_stub(void *addr) {

            printf("stubbed free(%p)\n", addr);

        }

        ''')

        # patch the beginning of free() with a jump to our new function

        pt.patch(old_free, jmp=new_free)

API

----

    addr = search(data)

    hook(addr, new_addr)

    patch(addr, *compile arg*)

    addr = inject(*compile arg*)

    *compile arg* is any of the following:

      raw='data'

      hex='0bfe'

      asm='nop'

      jmp=0xaddr

      c='void func() { int a; a = 1; }' (only supported on inject, not patch)

IDA scripts

----

Some scripts live in the ida/ path. Run them like this:

    /Applications/IDA\ Pro\ 6.8/idaq.app/Contents/MacOS/idaq64 -A -Sida/allfuncs.py a.out

When invoked like this, allfuncs.py will generate `a.out.funcs` which is used by hardening scripts.

Tools

----

These are somewhat CGC and x86-specific right now, but will be ported for general use in the future.

- explore: uses a Python CFG and recursive backtracking emulator to find basic blocks in an executable

- bindiff: uses the block boundaries from an explore run, as well as additional analysis to find and output basic block diffs between two binaries

Dependencies

----

- Run `./deps.sh` to automatically install these.

  - Capstone Engine - https://github.com/aquynh/capstone.git

  - Keystone Engine - https://github.com/keystone-engine/keystone.git

  - Unicorn Engine  - https://github.com/unicorn-engine/unicorn.git