Pierluigi Paganini
August 31, 2014
The researcher Dominique Bongard has presented an improvement for the attack on wireless routers with poorly implemented versions of the WPS (Wi-Fi Protected Setup).
The WPS is a popular network security standard that allows users to easily secure a wireless home network, but it knows that threat actors could brute-force it if the network’s access point is not properly configured.
The brute-force attack exploits weak randomization for the generation of a key used to authenticate hardware PINs on some implementations of WPS, the attackers can collect quickly information that allows them to guess the PIN through offline calculations.
“It takes one second,” “It’s nothing. Bang. Done.” Dominique Bongard said
The offline calculation allows the attacker to remain under the radar because he doesn’t need to try all possible combinations of digits that compose the numerical password.
Usually an efficient attack against the WPS required up to 11,000 guesses, which is a small number of attempts that could be executed approximately in four hours.
In 2011, the researcher Stefan Viehböck demonstrated several design flaws in WPS. Most important is the fact that the PIN used to complete the setup of wireless router could be broken in smaller parts that could be attacked separatelly. The technique allows the attacker to reduce the complexity of the attack, with 11,000 guesses it is possible to discover the password, the expert Craig Heffner of Tactical Network Solutions also discovered the security issue and created a tool, Reaver, to find the PIN.
Dominique Bongard has demonstrated at the recent PasswordsCon Las Vegas 2014 conference an evolution of the attack presented by Viehböck.
The new attack to discover the PIN to access the router WPS functionality just needs a series of offline calculations and a single guess.
The security issue affects the WPS implementations of two chipset manufacturers, Broadcom and a second vendor whom Bongard will not disclose until it will fix the security flaw.
As explained by the researcher the WPS implementation of Broadcom chipset had poor randomization, while the second vendor used a special seed which not ensure the randomness of the process. The above chipset are used in many routers of different manufacturers for this reason the problem is much more extended.
The Wi-Fi Alliance could not confirm whether the products impacted by the attack were certified, according to spokeswoman Carol Carrubba.
“A vendor implementation that improperly generates random numbers is more susceptible to attack, and it appears as though this is the case with at least two devices,” “It is likely that the issue lies in the specific vendor implementations rather than the technology itself. As the published research does not identify specific products, we do not know whether any Wi-Fi certified devices are affected, and we are unable to confirm the findings.” said Carol Carrubba, spokeswoman of the Wi-Fi Alliance that created the standard.
Dominique Bongard concludes the presentation inviting to disable the WPS as soon as possible.
(Security Affairs – WPS, Wi-Fi)
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