Wednesday, February 13, 2013

WPS Attack Detection and Reaction

For those of us in the security industry we are well aware that reactions to attacks can take vendors a long time to develop and deploy a preventative measure.  This is especially true with embedded devices that have no auto-update feature and/or are completely forgotten about once they are up and running on the network.

As a refresher in December of 2011 an attack was published that targeted a weakness in the Wi-Fi Protected Setup (WPS) protocol that demonstrates how to significantly decrease the amount of attempts needed to derive a valid WPS PIN during a brute force attack.  This attack leaves most routers that have WPS enabled vulnerable to an attack that will allow an attacker to learn the WPA Pre-Shared Key (PSK) or WEP key as well as gain access to more configuration information.

Click here to see a video of an attack against WPS using SILICA.

Most routers are still vulnerable to this attack today because there is no easy way to disable WPS in the router's configuration interface (a regular user is not going to go through the trouble of modifying firmware) and not very many people/organizations are very good about checking for and updating new firmware.  I should probably also mention the probability that most people that use or administer a wireless router are completely oblivious to the fact that there is such a weakness in WPS and don't disable it even if they can (after all it is a protocol meant to provide a convenient method to the admin and network users).

Even though it usually takes a long time for vendors to respond to this kind of attack we have recently seen a change in Netgear's firmware that actually addresses the security weakness.  Take a look at the following section taken from a Netgear R6300 web interface:

This is the first vendor response that I have seen for the WPS PIN attack.  After 3 failed attempts the feature is disabled and you get the following message next to the feature configuration: 


This obviously does offer another avenue of attack in the tune of a not-so-exciting denial of service (DoS) making it easy for an attacker to turn off WPS all together.

This slightly changes the game (and by slightly I mean not very much).  It used to be that identifying that WPS is enabled was all an attacker needed to determine if the AP was vulnerable to this attack (no major or minor versions to check before launching the attack - it's kind of the same feeling you get when you are pentesting a ColdFusion server/application; it doesn't matter the version you just know it's vulnerable). 

The WPS bug and attack are not going anywhere for a long time but it's interesting to see the proactive actions of vendors hoping for an eventual extinction.  I will keep you posted if I see any similar trends.

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