WPA2 Wi-Fi protocol has a built-in vulnerability


WPA2Most Wi-Fi enabled devices – computer, phone, tablet, e-reader and watches are likely to be affected, and they will need manufacturer’s updates to block it. Before this, some safety comes from it being a wireless rather than Internet-based vulnerability, probably, so would-be exploiters have to be physically local.

WPA2

In a paper ‘Key reinstallation attacks: Forcing nonce reuse in WPA2‘, to be presented as CCS’17 (Dallas, 30oct-03nov), Mathy Vanhoef and Frank Piessens will describe in detail how the attach works – by making use of something compulsory in the Wi-Fi standards.

“The recently-disclosed key re-installation attacks are a series of serious weaknesses in the WPA2 protocol that is used to secure the vast majority of modern Wi-Fi networks,” said Sebastien Jeanquier, consultant at Context Information Security.

“An attacker within range of a Wi-Fi client can trick that client into using a cryptographic key that the attacker is able to calculate, thus allowing the attacker to decrypt and eavesdrop on all of the network traffic between the Wi-Fi client and the Access Point. This could allow the attacker to steal usernames and passwords, as well as personal or financial information. The vulnerabilities are within the Wi-Fi standard itself and not individual products or implementations. As such, all Wi-Fi enabled devices should be considered affected and vulnerable, until a patch is made available by their respective vendors.”

Wi-Fi LogoAccording to Jeanquier, no attack software has been released, “although it is not inconceivable that attackers could create their own tools to perform such an attack.

VPN

Before fixes are applied, he suggests using Ethernet or 4G instead of Wi-Fi, and connecting via encryption is Wi-Fi is unavoidable – by virtual private network (VPN), or only communicating with websites whose URL’s start ‘https://’ – with the ‘s’ being the important bit.

According to the Vanhoef/Piessens CCS paper, when a client joins a network, it executes the 4-way handshake to negotiate a fresh session key and then sends a certain message.

Because connections can be dropped, there is a mechanism that re-uses the same key to send the same message – and this is where the trouble starts.



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