Vulnerability CVE-2021-4160

Vulnerability Name:

CVE-2021-4160 (CCN-218394)

Assigned:

2021-12-23

Published:

2022-01-28

Updated:

2022-11-09

Summary:

There is a carry propagation bug in the MIPS32 and MIPS64 squaring procedure. Many EC algorithms are affected, including some of the TLS 1.3 default curves. Impact was not analyzed in detail, because the pre-requisites for attack are considered unlikely and include reusing private keys. 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 DH are considered just feasible (although very difficult) 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 DH private key among multiple clients, which is no longer an option since CVE-2016-0701. This issue affects OpenSSL versions 1.0.2, 1.1.1 and 3.0.0. It was addressed in the releases of 1.1.1m and 3.0.1 on the 15th of December 2021. For the 1.0.2 release it is addressed in git commit 6fc1aaaf3 that is available to premium support customers only. It will be made available in 1.0.2zc when it is released. The issue only affects OpenSSL on MIPS platforms. Fixed in OpenSSL 3.0.1 (Affected 3.0.0). Fixed in OpenSSL 1.1.1m (Affected 1.1.1-1.1.1l). Fixed in OpenSSL 1.0.2zc-dev (Affected 1.0.2-1.0.2zb).

CVSS v3 Severity:

5.9 Medium (CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N)
5.2 Medium (Temporal CVSS v3.1 Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N/E:U/RL:O/RC:C)

Exploitability Metrics:	Attack Vector (AV): Network Attack Complexity (AC): High Privileges Required (PR): None User Interaction (UI): None
Scope:	Scope (S): Unchanged
Impact Metrics:	Confidentiality (C): High Integrity (I): None Availibility (A): None

6.7 Medium (CCN CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N)
5.8 Medium (CCN Temporal CVSS v3.1 Vector: CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N/E:U/RL:O/RC:C)

Exploitability Metrics:	Attack Vector (AV): Local Attack Complexity (AC): High Privileges Required (PR): None User Interaction (UI): None
Scope:	Scope (S): Unchanged
Impact Metrics:	Confidentiality (C): High Integrity (I): High Availibility (A): None

CVSS v2 Severity:

4.3 Medium (CVSS v2 Vector: AV:N/AC:M/Au:N/C:P/I:N/A:N)

Exploitability Metrics:	Access Vector (AV): Network Access Complexity (AC): Medium Authentication (Au): None
Impact Metrics:	Confidentiality (C): Partial Integrity (I): None Availibility (A): None

5.6 Medium (CCN CVSS v2 Vector: AV:L/AC:H/Au:N/C:C/I:C/A:N)

Exploitability Metrics:	Access Vector (AV): Local Access Complexity (AC): High Athentication (Au): None
Impact Metrics:	Confidentiality (C): Complete Integrity (I): Complete Availibility (A): None