From IP ID to Device ID and KASLR Bypass (Extended Version)
This work exposes a significant privacy and security vulnerability affecting billions of devices running Windows, Linux, and Android, enabling remote tracking and kernel attacks.
The researchers demonstrated that the IP ID field in network headers can be used to uniquely identify devices across browsers and network changes, and in Linux/Android, it leaks kernel addresses to bypass KASLR, with practical key extraction techniques validated in real-world tests.
IP headers include a 16-bit ID field. Our work examines the generation of this field in Windows (versions 8 and higher), Linux and Android, and shows that the IP ID field enables remote servers to assign a unique ID to each device and thus be able to identify subsequent transmissions sent from that device. This identification works across all browsers and over network changes. In modern Linux and Android versions, this field leaks a kernel address, thus we also break KASLR. Our work includes reverse-engineering of the Windows IP ID generation code, and a cryptanalysis of this code and of the Linux kernel IP ID generation code. It provides practical techniques to partially extract the key used by each of these algorithms, overcoming different implementation issues, and observing that this key can identify individual devices. We deployed a demo (for Windows) showing that key extraction and machine fingerprinting works in the wild, and tested it from networks around the world.