During RSA key generation, bignum implementations used a variation of the Binary Extended Euclidean Algorithm which entailed significantly input-dependent flow. This allowed an attacker able to perform electromagnetic-based side channel attacks to record traces leading to the recovery of the secret primes. Note: An unmodified Firefox browser does not generate RSA keys in normal operation and is not affected, but products built on top of it might. This vulnerability affects Firefox < 78.

References

• https://nvd.nist.gov/vuln/detail/CVE-2020-12402
• https://bugzilla.mozilla.org/show_bug.cgi?id=1631597
• https://lists.debian.org/debian-lts-announce/2020/09/msg00029.html
• https://lists.fedoraproject.org/archives/list/[email protected]/message/RFL6UNFK4MG2WDXLMLFAEIUSM5EUK7CG/
• https://lists.fedoraproject.org/archives/list/[email protected]/message/UWVDJRARXNWWWTCGMM63EXLQHH2LNOXO/
• https://security.gentoo.org/glsa/202007-10
• https://usn.ubuntu.com/4417-1/
• https://usn.ubuntu.com/4417-2/
• https://www.debian.org/security/2020/dsa-4726
• https://www.mozilla.org/security/advisories/mfsa2020-24/
• http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00016.html
• http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00018.html
• http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00027.html
• http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00049.html