rsaz_1024_mul_avx2 overflow bug on x86_64 (CVE-2017-3738) ========================================================= Severity: Low There is an overflow bug in the AVX2 Montgomery multiplication procedure used in exponentiation with 1024-bit moduli. No EC algorithms are affected. Analysis suggests that attacks against RSA and DSA as a result of this defect would be very difficult to perform and are not believed likely. Attacks against DH1024 are considered just feasible, because most of the work necessary to deduce information about a private key may be performed offline. The amount of resources required for such an attack would be significant. However, for an attack on TLS to be meaningful, the server would have to share the DH1024 private key among multiple clients, which is no longer an option since CVE-2016-0701. This only affects processors that support the AVX2 but not ADX extensions like Intel Haswell (4th generation). Note: The impact from this issue is similar to CVE-2017-3736, CVE-2017-3732 and CVE-2015-3193. Due to the low severity of this issue we are not issuing a new release of OpenSSL 1.1.0 at this time. The fix will be included in OpenSSL 1.1.0h when it becomes available. The fix is also available in commit e502cc86d in the OpenSSL git repository. OpenSSL 1.0.2 users should upgrade to 1.0.2n This issue was reported to OpenSSL on 22nd November 2017 by David Benjamin (Google). The issue was originally found via the OSS-Fuzz project. The fix was developed by Andy Polyakov of the OpenSSL development team.
This issue was resolved and addressed in GLSA 201712-03 at https://security.gentoo.org/glsa/201712-03 by GLSA coordinator Thomas Deutschmann (whissi).
