CVE-2022-0002

Published: 8 March 2022

Non-transparent sharing of branch predictor within a context in some Intel(R) Processors may allow an authorized user to potentially enable information disclosure via local access.

From the Ubuntu Security Team

Enrico Barberis, Pietro Frigo, Marius Muench, Herbert Bos, and Cristiano Giuffrida discovered that hardware mitigations added by Intel 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
this issue is priority medium for trusty/3.13 kernels, as
unprivileged BPF was not yet available in the Linux kernel of that
era.

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://www.vusec.net/projects/bhi-spectre-bhb/
• https://www.intel.com/content/www/us/en/developer/articles/technical/software-security-guidance/technical-documentation/branch-history-injection.html
• https://community.intel.com/t5/Blogs/Products-and-Solutions/Security/Chips-Salsa-Episode-12-March-2022-Security-Advisories/post/1365250
• https://intel.com/content/www/us/en/security-center/advisory/intel-sa-00598.html
• 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-5319-1
• https://www.cve.org/CVERecord?id=CVE-2022-0002
• NVD
• Launchpad
• Debian