- AMD finds four faults, separately low in gravity, but powerful when combined
- Together, they can be mistreated in information disclosure attacks
- The list of assigned devices is quite extensive, so be on your guard
AMD has discovered that several security vulnerabilities affecting many of its chips can be chained to create a hack concerning that could cause information to disclose.
The four vulnerabilities are followed in the form of CVE-2024-36349 (3.8), CVE-2024-36348 (3.8), CVE-2024-36357 (5.6) and CVE-2024-36350 (5.6). Together, they can be used in a so-called transitional planner attack (TSA), a lateral channel or an attack based on the calendar which probably uses transitional planning decisions taken by the processor planner to disclose information.
As it is a lateral channel attack which leads to a disclosure of information, it is similar to the infamous fusion and the spectrum faults that have dominated the security scene for months.
Systems update
In addition, vulnerabilities have received relatively low severity scores, as devices must be compromised in advance, either by physical presence or by malware, before they can be exploited.
In addition, the TSA should be executed several times before significant data can be extracted.
Here’s how a theoretical attack would happen: a CPU expects the loading instructions to end fairly quickly. However, if there is a condition that prevents them from doing so, a “false completion” occurs. Since the load has not ended, the data of the load is transmitted to the dependent operations, affecting the time of the instructions that the CPU performs – something that the attackers can observe.
The worst case is that AMD chips flee information from the operating system kernel – but other applications or virtual machines could also disclose data.
A fix is already available and AMD has advised system administrators to update the latest Windows versions as soon as possible.
Those who are unable to install the patch quickly can implement a bypass solution involving VOW instruction, but AMD advised to do so because it could reduce system performance. In any case, details on attenuation can be found here.
The complete list of all affected chips, including Epyc, Ryzen, Instinct, Ahtlon and others, is in the AMD council.
Via The register
