Overview of the KRACK Wi-Fi Attack

The Key Reinstallation Attack (KRACK) Wi-Fi Issue


Much has been written about the research performed by Mathy Vanhoef who recently published “Key Reinstallation Attacks: Forcing Nonce Reuse in WPA2.”  While the paper was completed in mid-May, it was not publicly released until just recently, allowing vendors time to implement fixes.  Fortunately there is a website that provides updated information on vendors that have provided fixes for this issue.

How the KRACK attack works, according to  Vanhoef’s research:

First of all, this is a proximity hack, thus an attacker that wishes to exploit this must be in physical proximity to the router/access point and the client.  The process by which a client connects to a Wi-Fi network involves a four-way handshake process through which a client negotiates a session key.  The key is installed once a client receives message 3 of the handshake; thus if an access point sends message 3 and does not receive an acknowledgement it will re-transmit.  When this happens, message 3 may be resent multiple times and each time the same session key will be reinstalled and the incremental transmit packet number (nonce) will be reset.  Consequently, an attacker can force message 3 retransmits and in so doing force nonce reuse and packets can be replayed, forged, and/or decrypted.

An overview of the KRACK vulnerability is explained in this video:

What you should do:

  • apply patches and updates regularly — vendors are releasing updates for KRACK so stay up to date
    • If your ISP isn’t releasing firmware updates for your router, consider switching or moving to customer-owned vs. rented/leased equipment
    • use cellular data vs. wi-fi on your mobile devices until your device is patched
  • use a VPN to encrypt all of your network packets — as this article points out however, be aware of the VPN service you use
  • use wired connections vs. wireless if that is an option for you
  • if you have Internet of Things (Iot) devices consider placing them offline until fixes are available
  • use HTTPS everywhere which works on Chrome, Firefox (and Firefox on Android), and Opera — https traffic is encrypted and not vulnerable to KRACK

This should serve as yet another reminder of how vulnerable our devices and our data remain. WPA2 was a well-baked standard that was implemented  years ago, the 4-way handshake is over fourteen years old.  Be aware of your surroundings, take care when using Wi-Fi hotspots and practice good cyber hygiene.

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Professor William Snyder

Professor William C. Snyderis a member of the faculty of the Institute for National Security and Counter-terrorism at Syracuse University after fifteen years with the United States Department of Justice.

Ryan D. White

Ryan D. WhiteRyan is currently a third year law student at Syracuse University College of Law, and is also pursuing a Master of Public Administration degree from Syracuse’s Maxwell School of Citizenship and Public Affairs. Ryan spent time with Homeland Security Investigations while pursuing his undergraduate degree at Wesleyan University, and spent his first summer of law school as clerk for the U.S. Attorney’s Office in the Western District of New York. He is a member of Syracuse Law Review, the Journal on Terrorism and Security Analysis, and participates in the Veteran’s Legal Clinic. Full biography

Shelby E. Mann

Ryan D. WhiteShelby is a second year law student at the Syracuse University College of Law. She is the 2018-9 Editor in Chief of the Syracuse Law Review, as well as a member of the Journal on Terrorism and Security Analysis, and the senior editor for the Syrian Accountability Project. During her final year at the University of Missouri, she served as a full-time news producer for ABC 17 News. Shelby spent her first summer of law school at the Shelby County District Attorney General's Office in Memphis, Tenn., in the Public Corruption and Economic Crimes Unit. Full biography

Christopher w. FolkChristopher W. Folk

is a 2017 graduate of SU College of Law. A non-traditional student, Christopher returned to academia after spending nearly twenty years in the high tech industry. Christopher served in the Marine Corps, graduated from Cornell University with a B.S. In Applied Economics and Business Management, attended Northeastern University’s High-Tech MBA Program and received a M.S. In Computer Information Systems. Christopher previously worked in Software Engineering. Christopher is currently serving his second term as Town Justice for the Town of Waterloo. Christopher externed with a Cybersecurity firm in the Washington, D.C. area between his first and second year at SU College of Law. Full biography

Anna Maria Castillo

Anna Maria Castillois 2016 graduate of Syracuse College of Law. She also holds a Master of Arts in International Relations from Syracuse University's Maxwell School of Citizenship and Public Affairs. She has interned at a London-based think-tank that specializes in transnational terrorism and global security and at the legal department of a defense contractor. She served as an executive editor in the Syracuse Law Review. Full biography

Jennifer A. CamilloJennifer A. Camillo

is a 2015 graduate of Syracuse College of Law and is a prosecutor. She has served as a law clerk in the United States Attorney’s Office for the Northern District of New York and the Cayuga County District Attorney’s Office and as an extern in the Oneida County District Attorney’s Office. She was a member of the Syracuse National Trial Team and was awarded the Tiffany Cup by the New York Bar Association for her trial advocacy achievements.

Tara J. PistoreseTara J. Pistorese

holds Juris Doctor and Masters of Public Administration degrees from Syracuse University's Maxwell School of Citizenship and Public Affairs and its College of Law. She wrote for this blog when a student. She is now a member of the U.S. Army Judge Advocate General's Corps.

Benjamin Zaiser

is both a scholar and a Federal Agent of the Federal Criminal Police Office of Germany. (Opinions expressed here are his own and not any part of official duty.) Full biography


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