Researcher Frost released a paper showing how a web page can infer high‑resolution SSD access timings through the Origin‑Private File System (OPFS). By repeatedly reading small files stored in OPFS, the script measures subtle latency differences that correlate with underlying SSD operations, effectively turning a standard browser into a remote timing sensor.

The technique exploits the fact that OPFS interactions bypass many traditional sandbox mitigations, allowing attackers to observe microsecond‑scale variations. Frost’s experiments on multiple browsers reveal consistent fingerprinting signatures across operating systems, suggesting that the method scales beyond isolated test environments. This adds a new vector to the growing suite of side‑channel attacks targeting web platforms.

Because OPFS is part of the HTML5 file handling API, developers cannot simply disable it without breaking legitimate use cases. Mitigations will likely require tighter timing granularity controls or noise injection at the file‑system layer. Until browsers address the issue, any site that can host OPFS‑enabled scripts could harvest device‑specific timing data.