binary patching from Python
Patches an ELF binary using one or more simple Python scripts.
Usage:
patch [patchdir|file...]Contains one or more Python patch files, which will be executed in alphabetical order against a binary.
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)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)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.outWhen invoked like this, allfuncs.py will generate a.out.funcs which is used by hardening scripts.
These are somewhat CGC and x86-specific right now, but will be ported for general use in the future.
./deps.sh to automatically install these.No open issues yet, or sync has not completed.