NSA Spied On Encrypted Traffic (Including VPNs) For A Decade
By Paul Liu
Thursday, March 16th, 2017
The recent leak of NSA’s cyber weapons has certainly opened a Pandora’s box. The episode has not only confirmed that NSA was able to find tons of vulnerabilities in US-made security products, it even shows that the agency was using them to launch cyber-attacks against other governments and private organizations. And as if this was not enough, it has now come to light that NSA was able to spy on encrypted traffic (including VPN traffic) for as many as 10 years. The agency achieved this feat by exploiting a vulnerability present within a decommissioned line of Cisco’s firewall product.
The cache of code released by the Shadow Brokers group contained an attack tool known as BenignCertain. The tool is very similar to the Heartbleed flaw which caused widespread disruptions in online traffic in the year 2014. As per the researchers who have analyzed the code of BenignCertain, the program worked on Cisco’s PIX line of firewalls which was released in 2002. Cisco stopped providing bug fixes and updates for that version in 2009 although the company did offer limited support for it for 4 more years.
BenignCertain works by bombarding PIX servers with custom created requests. It turns out that appending the Internet Key Exchange (IKE) to the request would cause a PIX server to dump lots of information from its memory. When the process is repeated sufficient number of times, attackers would get bits of password along with the dumped information. Thus, the vulnerability allowed the attackers to get the firewall password and eventually hack it by supplying the correct credentials. In the aftermath of the NSA leak, three separate researchers were able to prove that BenignCertain did work on PIX installations which are currently in use.
A lot of PIX firewalls were used in real life to run VPN installations via the IPSec protocol. This means that any organization using the product could have been spied on by the NSA. Also, since BenignCertain is able to retrieve decryption keys from the PIX server, the agency could even have gained full access to a network via remote access tools. Edward Snowden had earlier confirmed that NSA had the ability to decrypt 1000 VPN connections per hour by 2009 and as many as 100,000 per hour by the year 2011. While it is not clear whether BenignCertain was used in the decryption jobs, it is highly possible that the tool was part of NSA’s arsenal.
Cisco has decline to evaluate the vulnerability citing that the product is no longer being supported. However, security experts believe that a lot of organizations are still using the compromised version of firewall within their organizations. It is still not known whether any VPN provider is using that version of the firewall but if they are doing so, their traffic can easily be studied by the spy agency. It also remains to be seen whether other attack tools released in the leak were being used to decrypt traffic or break VPN connections. One thing is certain, if an organization is still using compromised PIX firewalls and is using IPSec as an encryption protocol then their traffic is no longer encrypted.