Normally in OpenSSL EC groups always have a co-factor present and this is used in side channel resistant code paths. However, in some cases, it is possible to construct a group using explicit parameters (instead of using a named curve). In those cases it is possible that such a group does not have the cofactor present. This can occur even where all the parameters match a known named curve. If such a curve is used then OpenSSL falls back to non-side channel resistant code paths which may result in full key recovery during an ECDSA signature operation. In order to be vulnerable an attacker would have to have the ability to time the creation of a large number of signatures where explicit parameters with no co-factor present are in use by an application using libcrypto. For the avoidance of doubt libssl is not vulnerable because explicit parameters are never used. Fixed in OpenSSL 1.1.1d (Affected 1.1.1-1.1.1c). Fixed in OpenSSL 1.1.0l (Affected 1.1.0-1.1.0k). Fixed in OpenSSL 1.0.2t (Affected 1.0.2-1.0.2s).
https://www.openssl.org/news/secadv/20190910.txt
https://arxiv.org/abs/1909.01785
https://seclists.org/bugtraq/2019/Sep/25
http://packetstormsecurity.com/files/154467/Slackware-Security-Advisory-openssl-Updates.html
https://security.netapp.com/advisory/ntap-20190919-0002/
http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00054.html
http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00072.html
https://lists.debian.org/debian-lts-announce/2019/09/msg00026.html
https://seclists.org/bugtraq/2019/Oct/1
https://seclists.org/bugtraq/2019/Oct/0
https://www.debian.org/security/2019/dsa-4539
https://www.debian.org/security/2019/dsa-4540
http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00012.html
http://lists.opensuse.org/opensuse-security-announce/2019-10/msg00016.html
https://support.f5.com/csp/article/K73422160?utm_source=f5support&utm_medium=RSS
https://www.oracle.com/technetwork/security-advisory/cpuoct2019-5072832.html
https://security.gentoo.org/glsa/201911-04
https://www.tenable.com/security/tns-2019-08
https://www.tenable.com/security/tns-2019-09
https://www.oracle.com/security-alerts/cpujan2020.html
https://security.netapp.com/advisory/ntap-20200122-0002/
https://www.oracle.com/security-alerts/cpuapr2020.html
https://usn.ubuntu.com/4376-1/
https://security.netapp.com/advisory/ntap-20200416-0003/
https://www.oracle.com/security-alerts/cpujul2020.html
https://usn.ubuntu.com/4376-2/
https://usn.ubuntu.com/4504-1/
https://www.oracle.com/security-alerts/cpuoct2020.html
https://kc.mcafee.com/corporate/index?page=content&id=SB10365
Source: MITRE
Published: 2019-09-10
Updated: 2021-07-31
Type: NVD-CWE-noinfo
Base Score: 1.9
Vector: AV:L/AC:M/Au:N/C:P/I:N/A:N
Impact Score: 2.9
Exploitability Score: 3.4
Severity: LOW
Base Score: 4.7
Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
Impact Score: 3.6
Exploitability Score: 1
Severity: MEDIUM