This Week in Security: New Spectre Attacks

Just-in-time, or JIT, compilation could be considered a fundamental backbone of modern computing. JIT compilation turns scripting languages like JavaScript or intermediary binary forms like Web Assembly into native code …. This Week in Security: New Spectre Attacks, Crushing Quantity of Linux Vulns, Google Gets Too Much AI, and Hacking Lawnmowers.

JIT compilation turns scripting languages like JavaScript or intermediary binary forms like Web Assembly into native code on the fly, giving web apps, and things that are web apps under the covers like Electron-based tools, near native speed. A new paper explores leveraging JIT systems to revive Spectre-v2 attacks against processors. Most modern processors gain performance by using a trick called “speculative execution”.

The processor guesses the likely result of a compare, and begins executing some of the next instructions before the results are actually known. If the processor guessed right, things continue and there is a speed gain because it can jump ahead, but if the processor guessed wrong, any instructions that were run and any side effects of running them are discarded and execution resumes on the actual path. In practice, the Spectre class of attacks targets branch prediction.

It was discovered that when the wrong branch was chosen, not all of the results were truly hidden; Patterns of failures in guessing branches can be used to leak behavior processing encryption keys and other activities.