-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 OpenSSL Security Advisory [15 March 2022] ============================================ Infinite loop in BN_mod_sqrt() reachable when parsing certificates (CVE-2022-0778) ================================================================================== Severity: High 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. OpenSSL 1.0.2 users should upgrade to 1.0.2zd (premium support customers only) OpenSSL 1.1.1 users should upgrade to 1.1.1n OpenSSL 3.0 users should upgrade to 3.0.2 This issue was reported to OpenSSL on the 24th February 2022 by Tavis Ormandy from Google. The fix was developed by David Benjamin from Google and Tomáš Mráz from OpenSSL. Note ==== OpenSSL 1.0.2 is out of support and no longer receiving public updates. Extended support is available for premium support customers: https://www.openssl.org/support/contracts.html OpenSSL 1.1.0 is out of support and no longer receiving updates of any kind. It is affected by the issue. Users of these versions should upgrade to OpenSSL 3.0 or 1.1.1. References ========== URL for this Security Advisory: https://www.openssl.org/news/secadv/20220315.txt Note: the online version of the advisory may be updated with additional details over time. For details of OpenSSL severity classifications please see: https://www.openssl.org/policies/secpolicy.html -----BEGIN PGP SIGNATURE----- iQEzBAEBCAAdFiEEhlersmDwVrHlGQg52cTSbQ5gRJEFAmIwtOcACgkQ2cTSbQ5g RJGd6wf/VColq7YEnA1dKQvd75ytnFkV8tUhb1uQ9eCjhxk76ASg3QToEar3yDd3 ykGXJZy5oPCl0zG33GORz9Pq8oWjIoCDLfhlTh3aORjWZ9uMkd+RWxVEjxyidgZp 4Rb8p5qSncxJ1EcYLoeUWu/lrDh67q1hDnwGNtNxyzVC0sqxWz++YoFXGJA2OH0m lcYZilUdZ4HLVKmFKEfQGX/xwdvxj3VTaJNjsEI+2h1xysXBN+TpXsEL2yOGx8Cq KzQXnRUrNhsdIQYEAJ7i3HXYmY0wHehTXvBoZsI/2yWiC19WWK8u/qZxdc3Y88v3 JDKNJRCyKGbji+ESZPnWB14yE3yZ0g== =9ROi -----END PGP SIGNATURE-----
