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WPA2 and Key Reinstallation Attacks (KRACKs)

Mathy Vanhoef, a researcher with imec-DistriNet Research Group posted a research paper that details WPA2 based attacks the aptly named KRACKs vulnerabilities.

KRACKs exploits the way WPA2 WiFi is used during the initial handshake process, the paper details how the 3rd step in a 4-way handshake process which provides a unique encryption key used specifically for that WiFi session can be forced to reissue that same unique encryption key. The WPA2 protocol allows for error detection, in effect when the client does not confirm it has received the unique key the WPA2 server will reissue that same unique key.

An attacker can use this knowledge to delay a completed connection between server and client, and use the unique encryption key to decrypt packets sent from client to server.

In more serious cases Linux’s wpa_supplicant v2.6 is vulnerable to the installation of an all-zero encryption key in the 4-way handshake. This was discovered by John A. Van Boxtel. As a result, all Android versions higher than 6.0 are also affected by the attack, and hence can be tricked into installing an all-zero encryption key.

The weaknesses are in the Wi-Fi standard itself, and not in individual products or implementations. Therefore, any correct implementation of WPA2 is likely affected. To prevent the attack, users must update affected products as soon as security updates become available.

There are a number of CVE reference numbers issued, each designed to track a specific vulnerable product.

CVE-2017-13077, CVE-2017-13078, CVE-2017-13079, CVE-2017-13080, CVE-2017-13081, CVE-2017-13082, CVE-2017-13084, CVE-2017-13086, CVE-2017-13087, CVE-2017-13088

The following Qualys QID’s have been created to test for KRACK based vulnerabilities:

196947,176179,123582,123015,165336

Qualys customers can copy & paste this list into a static searchlist for use in scans or reports.

Customers can rescan if Qualys is deployed via traditional TCP/IP scanning but this is not required for agent based Qualys deployments.

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