A flaw was found in hw. The Branch History Injection (BHI) describes a specific form of intra-mode BTI. This flaw allows an unprivileged attacker to manipulate the branch history before transitioning to supervisor or VMX root mode. This issue is an effort to cause an indirect branch predictor to select a specific predictor entry for an indirect branch, and a disclosure gadget at the predicted target will transiently execute. This execution is possible since the relevant branch history may contain branches taken in previous security contexts, and in particular, in other predictor modes.

A flaw was found in hw. The Intra-mode BTI refers to a variant of Branch Target Injection aka SpectreV2 (BTI) where an indirect branch speculates to an aliased predictor entry for a different indirect branch in the same predictor mode, and a disclosure gadget at the predicted target transiently executes. These predictor entries may contain targets corresponding to the targets of an indirect near jump, indirect near call, and near return instructions, even if these branches were only transiently executed. The managed runtimes provide an attacker with the means to create the aliasing required for intra-mode BTI attacks.

Last updated 24 July 2024