Fortinet: Vulnerability in OpenSSL library

Description

A security advisory was released affecting the version of OpenSSL library used in some Fortinet products:CVE-2022-0778:The BN_mod_sqrt() function, which computes a modular square root, contains a bug that can cause it to loop forever for non-prime moduli. Internally this function is used when parsing certificates that contain elliptic curve public keys in compressed form or explicit elliptic curve parameters with a base point encoded in compressed form. It is possible to trigger the infinite loop by crafting a certificate that has invalid explicit curve parameters. Since certificate parsing happens prior to verification of the certificate signature, any process that parses an externally supplied certificate may thus be subject to a denial of service attack. The infinite loop can also be reached when parsing crafted private keys as they can contain explicit elliptic curve parameters.Thus vulnerable situations include:TLS clients consuming server certificatesTLS servers consuming client certificatesHosting providers taking certificates or private keys from customersCertificate authorities parsing certification requests from subscribersAnything else which parses ASN.1 elliptic curve parametersAlso any other applications that use the BN_mod_sqrt() where the attacker can control the parameter values are vulnerable to this DoS issue.In the OpenSSL 1.0.2 version the public key is not parsed during initial parsing of the certificate which makes it slightly harder to trigger the infinite loop. However any operation which requires the public key from the certificate will trigger the infinite loop. In particular the attacker can use a self-signed certificate to trigger the loop during verification of the certificate signature.This issue affects OpenSSL versions 1.0.2, 1.1.1 and 3.0. It was addressed in the releases of 1.1.1n and 3.0.2 on the 15th March 2022.Fixed in OpenSSL 3.0.2 (Affected 3.0.0,3.0.1). Fixed in OpenSSL 1.1.1n (Affected 1.1.1-1.1.1m). Fixed in OpenSSL 1.0.2zd

What to do

Install the fixed versions listed in the official advisory. If you cannot update right away, apply the workarounds or mitigations it describes and limit access to the affected service.

Details

Vendor

Fortinet

Product

OpenSSL

CVE

CVE-2022-0778

Affected versions

OpenSSL 3.0: Fixed in OpenSSL 3.0.2 (Affected 3.0.0,3.0.1)
OpenSSL 1.1: Fixed in OpenSSL 1.1.1n (Affected 1.1.1-1.1.1m)
OpenSSL 1.0: Fixed in OpenSSL 1.0.2zd (Affected 1.0.2-1.0.2zc) (from the advisory and NVD; check the exact builds in the official advisory)

CVSS score

7.5

Actively exploited

Not known at this time

Source

Fortinet PSIRT – original advisory

Published

April 1, 2022

The description and the recommended action are quoted from the public advisory (the action is our generic advice); severity, exploitation status and affected versions are compiled automatically from public sources and may contain errors. The vendor's original advisory prevails: check it before taking action. This information is provided without warranty and does not replace a professional assessment.