Spectre V2

Spectre v2 is a software vulnerability that arises due to incorrect implementation of the Spectre v2 Simultaneous Multithreading (SMT) mitigations, specifically related to calling prctl with PR_SET_SPECULATION_CTRL. This flaw allows malicious code to exploit the shared branch history stored in the CPU Branch History Buffer (BHB), leading to mispredicted branches within the victim's hardware context. A similar vulnerability, known as Spectre-BHB, also uses this method to compromise system security. In response to these vulnerabilities, major tech companies have assured customers and stakeholders that current mitigation strategies are sufficient. Arm has published a security advisory stating that existing safeguards for Spectre v2 and Spectre BHB should effectively prevent potential exploitation. AMD has similarly stated that current Spectre v2 mitigations are effective against another exploit known as SLAM, identified by the VUSec research group. Intel, on the other hand, has committed to addressing the issue through software guidance. Despite these assurances, there remains some concern about the potential risk posed by these vulnerabilities. Both Arm and AMD, while confident in their current mitigations, have not provided any additional guidance or updates to further reduce the risk. Intel plans to provide software guidance before releasing processors which support a new feature called LAM. As such, while current mitigations are believed to be effective, ongoing vigilance and proactive measures are essential to maintain system security.