A novel side-channel attack called
GPU.zip renders virtually all modern graphics processing units (GPU) vulnerable to information leakage.
"This channel exploits an optimization that is data dependent, software transparent, and present in nearly all modern GPUs: graphical data compression," a group of academics from the University of Texas at Austin, Carnegie Mellon University, University of Washington, and the University of Illinois Urbana-Champaign
said.
Graphical data compression is a feature in integrated GPUs (iGPUs) that allows for saving memory bandwidth and improving performance when rendering frames, compressing visual data losslessly even when it's not requested by software.
The study found that the compression, which happens in various vendor-specific and undocumented ways, induces data-dependent
DRAM traffic and cache occupancy that can be measured using a side-channel.
"An attacker can exploit the iGPU-based compression channel to perform cross-origin pixel stealing attacks in the browser using SVG filters, even though SVG filters are implemented as constant time," the researchers said. "The reason is that the attacker can create highly redundant or highly non-redundant patterns depending on a single secret pixel in the browser. As these patterns are processed by the iGPU, their varying degrees of redundancy cause the lossless compression output to depend on the secret pixel."
