WGSA-2022-00011#
OpenSSL Certificate Processing DoS Vulnerability (CVE-2022-0778)
Summary #
On 15 March 2022, OpenSSL disclosed CVE-2022-0778, a bug in the BN_mod_sqrt() function responsible for calculating a modular square root, that could cause it to loop forever by crafting a certificate with invalid elliptic curve parameters. An attacker could exploit this vulnerability to trigger a Denial of Service attack against a vulnerable process.
CVE identifiers #
| CVE ID | Description | CVSS |
|---|---|---|
| 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 certificates - TLS servers consuming client certificates - Hosting providers taking certificates or private keys from customers - Certificate authorities parsing certification requests from subscribers - Anything else which parses ASN.1 elliptic curve parameters Also 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 (Affected 1.0.2-1.0.2zc). | — |
Product status #
| Product | Affected | Not affected |
|---|---|---|
| Dimension | — | All versions |
| Fireware OS | ||
| Default | >= 12.0, < 12.8-b659436 | >= 12.8-b659436 |
| T15/T35 | >= 12.5, < 12.5.9-b655824 | >= 12.5.9-b655824 |
| FIPS | >= 12.3.0, < 12.3.1_U2 | >= 12.3.1_U2 |
| Secure Wi-Fi | — | All versions |
| WatchGuard System Manager | >= 12.0, < 12.8-b656510 | >= 12.8-b656510 |
Solution #
Fireware OS 12.8-b659436, Fireware OS 12.5.9-b655824, Fireware OS 12.3.1_U2, WatchGuard System Manager 12.8-b656510