A safety vulnerability has been disclosed in AMD’s Safe Encrypted Virtualization (SEV) that would allow an attacker to load a malicious CPU microcode beneath particular circumstances.
The flaw, tracked as CVE-2024-56161, carries a CVSS rating of seven.2 out of 10.0, indicating excessive severity.
“Improper signature verification in AMD CPU ROM microcode patch loader may allow an attacker with local administrator privilege to load malicious CPU microcode resulting in loss of confidentiality and integrity of a confidential guest running under AMD SEV-SNP,” AMD mentioned in an advisory.
The chipmaker credited Google safety researchers Josh Eads, Kristoffer Janke, Eduardo Vela, Tavis Ormandy, and Matteo Rizzo for locating and reporting the flaw on September 25, 2024.
SEV is a safety characteristic that makes use of a novel key per digital machine to isolate digital machines (VMs) and the hypervisor from each other. SNP, which stands for Safe Nested Paging, incorporates reminiscence integrity protections to create an remoted execution surroundings and safeguard in opposition to hypervisor-based assaults.
“SEV-SNP introduces several additional optional security enhancements designed to support additional VM use models, offer stronger protection around interrupt behavior, and offer increased protection against recently disclosed side channel attacks,” in accordance to AMD.
In a separate bulletin, Google famous that CVE-2024-56161 is the results of an insecure hash operate within the signature validation for microcode updates, which opens the door to a state of affairs the place an adversary may compromise confidential computing workloads.
The corporate has additionally launched a check payload to show the vulnerability, however further technical particulars have been withheld for an additional month in order to present sufficient time for the repair to be propagated throughout the “deep supply chain.”
