Is Your Cisco Router Leaving Your Enterprise Vulnerable?

If your network uses Cisco's RV320 or RV325 Dual Gigabit WAN VPN routers, you are already under attack, whether you have realized it or not. The two routers are popular among Internet service providers and large enterprises.

There are two major vulnerabilities affecting these routers. One is a command injection (CVE-2019-1652) and the other an information disclosure (CVE-2019-1653).

CVE-2019-1653 requires no authentication, so a remote attacker can easily retrieve sensitive information including the router's configuration file, which includes MD5 hashed credentials as well as diagnostic information.

If the two are chained together by an attacker, they may obtain the hashed access credentials for a privileged account which then could give them the ability to run arbitrary commands as root.

German company RedTeam Pentesting first found these vulnerabilities in the routers, and reported them to Cisco. Cisco then issued a firmware update to mitigate the situation, along with an advisory.

In the advisory, Cisco stated the problem as "The vulnerability is due to improper validation of user-supplied input. An attacker could exploit this vulnerability by sending malicious HTTP POST requests to the web-based management interface of an affected device. A successful exploit could allow the attacker to execute arbitrary commands on the underlying Linux shell as root."

Cisco also says there are no workarounds for this.

Firmware Releases 1.4.2.15 through 1.4.2.19. are affected by these vulnerabilities.

However, there are already exploits on GitHub (one by David Davidson) that can serve as framework for an attack.

One of them can exploit CVE-2019-1653 and retrieve the configuration file from the router as well as the diagnostic information. This information includes hashed credentials for the router, which are hashed using MD5.

The md5 hash is md5($password.$auth_key), with the auth_key being a static value that can be simply discerned through the running of 'GET /' and parsing the output.

Threat actors are hoping that patching efforts will lag, and are racing to find those routers that are vulnerable.

Troy Mursch, a researcher from security firm Bad Packets, has found evidence of scans looking for these particular routers, and is trying to see which ones of the over 9,600 worldwide routers might be exploited. 6,247 were found to be Cisco RV320 routers, and 3,410 are Cisco RV325 routers.

He got the target number (out of the 20,000 that would show up in a Shodan search) through the use of BinaryEdge, a search engine for Internet-connected devices.

Most of these routers are located in use by US Internet service providers, according to a map that Mursh generated.

If you have not applied the update to the firmware, an emergency response might be to change their router's admin and WiFi credentials as well as assuming that you have already been compromised.

— Larry Loeb has written for many of the last century's major "dead tree" computer magazines, having been, among other things, a consulting editor for BYTE magazine and senior editor for the launch of WebWeek.