CVE-2022-23960

Published: 8 March 2022

Certain Arm Cortex and Neoverse processors through 2022-03-08 do not properly restrict cache speculation, aka Spectre-BHB. An attacker can leverage the shared branch history in the Branch History Buffer (BHB) to influence mispredicted branches. Then, cache allocation can allow the attacker to obtain sensitive information.

From the Ubuntu Security Team

Enrico Barberis, Pietro Frigo, Marius Muench, Herbert Bos, and Cristiano Giuffrida discovered that hardware mitigations added by ARM to their processors to address Spectre-BTI were insufficient. A local attacker could potentially use this to expose sensitive information.

Notes

unprivileged eBPF was already disabled by default for 5.13
and newer kernels
ARM specific issue

Mitigation

 To mitigate the primary known attack vector, disable unprivileged eBPF:
    $ sudo sysctl kernel.unprivileged_bpf_disabled=1
 or
    $ sudo sysctl kernel.unprivileged_bpf_disabled=2

Status

Severity score breakdown

References

• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-23960
• https://www.vusec.net/projects/bhi-spectre-bhb/
• https://developer.arm.com/support/arm-security-updates/speculative-processor-vulnerability/spectre-bhb
• https://developer.arm.com/documentation/ka004995/latest/
• https://wiki.ubuntu.com/SecurityTeam/KnowledgeBase/BHI
• https://ubuntu.com/security/notices/USN-5317-1
• https://ubuntu.com/security/notices/USN-5318-1
• https://ubuntu.com/security/notices/USN-5362-1
• NVD
• Launchpad
• Debian