Endpoint Vulnerability

rsaz_512_sqr overflow bug on x86_64


Severity: LowThere is an overflow bug in the x64_64 Montgomery squaring procedure used inexponentiation with 512-bit moduli. No EC algorithms are affected. Analysissuggests that attacks against 2-prime RSA1024, 3-prime RSA1536, and DSA1024 as aresult of this defect would be very difficult to perform and are not believedlikely. Attacks against DH512 are considered just feasible. However, for anattack the target would have to re-use the DH512 private key, which is notrecommended anyway. Also applications directly using the low level APIBN_mod_exp may be affected if they use BN_FLG_CONSTTIME.OpenSSL versions 1.1.1 and 1.0.2 are affected by this issue. However due to thelow severity of this issue we are not creating new releases at this time. The1.1.1 mitigation for this issue can be found in commit 419102400. The 1.0.2mitigation for this issue can be found in commit f1c5eea8a.This issue was found by OSS-Fuzz and Guido Vranken and reported to OpenSSL on12th September 2019. The fix was developed by Andy Polyakov with additionalanalysis by Bernd Edlinger.NoteOpenSSL 1.0.2 is currently only receiving security updates. Support for 1.0.2will end on 31st December 2019. Extended support is available for premiumsupport customers: https://www.openssl.org/support/contracts.htmlOpenSSL 1.1.0 is out of support and no longer receiving updates. It is unknownwhether issues in this advisory affect it.Users of these versions should upgrade to OpenSSL 1.1.1.ReferencesURL for this Security Advisory:https://www.openssl.org/news/secadv/20191206.txtNote: the online version of the advisory may be updated with additional detailsover time.For details of OpenSSL severity classifications please see:https://www.openssl.org/policies/secpolicy.html

Affected Products