In February 2020, information security specialists spoke at the RSA 2020 conference about the new Kr00k vulnerability (CVE-2019-15126), which can be used to intercept and decrypt Wi-Fi traffic (WPA2). According to analysts, any device that uses the solutions of Cypress Semiconductor and Broadcom, from laptops and smartphones to routers and IoT devices, is susceptible to this problem. Experts tested and confirmed the problem for iPhone, iPad, Mac, Amazon Echo and Kindle, Google Nexus, Samsung Galaxy, Xiaomi Redmi, Raspberry Pi 3, as well as Asus and Huawei Wi-Fi routers. In total, vulnerability threatens about a billion different gadgets.
The essence of the Kr00k problem comes down to encryption, which is used to protect data packets transmitted via Wi-Fi. Typically, such packets are encrypted with a unique key, which depends on the Wi-Fi password specified by the user. But for Broadcom and Cypress chips, this key is reset to zero if you initiate the process of dissociation (disassociation), that is, a temporary shutdown, which usually occurs due to a bad signal. Thus, attackers can provoke the transition of the device into a prolonged state of dissociation and receive the Wi-Fi packets intended for it. Then, by exploiting the Kr00k bug, attackers can decrypt Wi-Fi traffic using a “zero” key.
Now the Infosec Hexway Development Team created an exploit for this vulnerability. Researchers managed to exploit the bug using Raspberry Pi 3 and a Python script. As a result, they were able to extract keys and personal data from Sony Xperia Z3 Compact and Huawei Honor 4X devices using a vulnerable chipset.
“After testing this PoC on different devices, we found that the data from clients that generated a lot of UDP traffic is easiest to intercept. For example, among such clients there are various streaming applications, because this type of traffic (unlike small TCP packets) is always stored in the buffer of the Wi-Fi chip, ”the researchers write.
Also own exploit already created by specialists from Thice. Unlike colleagues, Thice experts report that the Kr00k problem may not be as dangerous as everyone believes:
“The amount of data that you can steal in this way is limited – only a couple of packets for each disconnection,” experts say.