A team of researchers at Georgia Tech, the University of Michigan, and Ruhr University Bochum have developed a novel attack called "Hot Pixels," which can retrieve pixels from the content displayed in the target's browser and infer the navigation history. The attack exploits data-dependent computation times on modern system-on-a-chip (SoCs) and graphics processing units (GPUs) and applies them to stealthily extract information from visited web pages on Chrome and Safari, even if with the latest side-channel countermeasures enabled.
The researchers found that modern processors struggle to balance power consumption requirements and heat dissipation limitations with high execution speeds. This leads to distinct behavior patterns that point to specific instructions and operations. These patterns are easily detectable through internal sensor measurements that are often accessible through software and, depending on the device type, can help discern what is viewed on the target device with an accuracy as high as 94%.By analyzing frequency, power, and temperature measurements on modern devices, the researchers concluded that passively cooled processors could leak information via power and frequency, while actively cooled chips leak data through temperature and power readings.