US-CERT Technical Cyber Security Alert TA12-006A -- Wi-Fi Protected Setup (WPS) Vulnerable to Brute-Force Attack

                    National Cyber Alert System

              Technical Cyber Security Alert TA12-006A

Wi-Fi Protected Setup (WPS) Vulnerable to Brute-Force Attack

   Original release date: January 06, 2012

   Last revised: --

   Source: US-CERT

Systems Affected

   Most Wi-Fi access points that support Wi-Fi Protected Setup (WPS)

   are affected.

Overview

   Wi-Fi Protected Setup (WPS) provides simplified mechanisms to

   configure secure wireless networks. The external registrar PIN

   exchange mechanism is susceptible to brute force attacks that could

   allow an attacker to gain access to an encrypted Wi-Fi network.

I. Description

   WPS uses a PIN as a shared secret to authenticate an access point

   and a client and provide connection information such as WEP and WPA

   passwords and keys. In the external registrar exchange method, a

   client needs to provide the correct PIN to the access point.

   An attacking client can try to guess the correct PIN. A design

   vulnerability reduces the effective PIN space sufficiently to allow

   practical brute force attacks. Freely available attack tools can

   recover a WPS PIN in 4-10 hours.

   For further details, please see Vulnerability Note VU#723755 and

   further documentation by Stefan Viehbock and Tactical Network

   Solutions.

II. Impact

   An attacker within radio range can brute-force the WPS PIN for a

   vulnerable access point. The attacker can then obtain WEP or WPA

   passwords and likely gain access to the Wi-Fi network. Once on the

   network, the attacker can monitor traffic and mount further

   attacks.

III. Solution

   Update Firmware

   Check your access point vendor's support website for updated

   firmware that addresses this vulnerability. Further information may

   be available in the Vendor Information section of VU#723755 and in

   a Google spreadsheet called WPS Vulnerability Testing.

   Disable WPS

   Depending on the access point, it may be possible to disable WPS.

   Note that some access points may not actually disable WPS when the

   web management interface indicates that WPS is disabled.