Understanding the Key Reinstallation Attack (KRACK) Wi-Fi vulnerability

Alyce KominetskyCybersecurity

KRACK logo: Logo designed to illustrate the attack targeting vulnerability of Wi-Fi networks' WPA2 security protocol

KRACK logo: Logo designed to illustrate the attack targeting vulnerability of Wi-Fi networks' WPA2 security protocol
A vulnerability in Wi-Fi encryption known as the Key Reinstallation Attack, or KRACK, has turned the IT industry on its head. Because it affects routers and countless other wireless devices that may never see a fix, KRACK’s implications may be felt for decades to come.

KRACK is a severe exploitable flaw of the Wi-Fi Protected Access (WPA) protocol that secures Wi-Fi connections. Routers and devices use this security protocol to encrypt people’s activity. More specifically, Wi-Fi networks typically use keys shared via a collection of cryptographic “handshakes” to protect network traffic. Executed when a client wants to join a protected Wi-Fi network, the handshake verifies both the identity of the client and the network access point. KRACK targets these handshakes, and anyone who uses a Wi-Fi-enabled device may be at risk of sharing unencrypted network traffic with attackers bypassing WPA2 network security.

That’s because KRACK causes the WPA protocol to reinstall an existing or predictable key. Once this happens, attackers can decrypt passwords, credit card numbers, emails and other sensitive data passing over the network. Decryption also makes it possible for attackers to inject malicious content (e.g., ransomware and malware) and manipulate data, replay captured data packets over the network, and forge and transmit new packets to the targeted client. By forging packets, attackers can join the network and pretend to be a client or the access point.

These vulnerabilities exist on most, if not all, wireless networking devices that use the protocol. This is because the weaknesses exist in the Wi-Fi standard itself, not in individual products or implementations. All major operating systems, and Android 6.0 in particular, are vulnerable to at least one form of the KRACK attack.

Using a reputable virtual private network (VPN) can keep you safe from KRACK attacks: the VPN encrypts your personal information and browsing, keeps your Internet activities from being tracked and safeguard your personal information from hacks when using public Wi-Fi hotspots.

Don’t assume that simply changing the password of your Wi-Fi network will prevent this attack: it won’t. Instead, patch affected products and devices as soon as security updates become available. This includes updating the firmware on your router.

Patches may prove effective on some devices; however, the majority of Internet of Things (IoT) devices (e.g., Internet-connected security cameras, garage doors and refrigerators) transmit data over Wi-Fi networks without adequate protections. What’s more, they rarely receive the necessary software updates to address security issues. As such, KRACK underlines just how susceptible they are to Internet‑hijacked connections.

Belgian researchers Mathy Vanhoef and Frank Piessens discovered serious weaknesses in the WPA2 protocol in 2016. Vanhoef disclosed the issue to various vendors and software manufacturers in July 2017, months before publishing details of the KRACK attack October 16, 2017. As such, a number of security-minded companies have had time to work on fixes and offer patches. The Wi-Fi Alliance has also announced that it has a plan to help remedy the discovered vulnerabilities in WPA2.