CVE-2023-3817 Information

Description

Issue summary: Checking excessively long DH keys or parameters may be very slow.

Impact summary: Applications that use the functions DH_check() DH_check_ex() or EVP_PKEY_param_check() to check a DH key or DH parameters may experience long delays. Where the key or parameters that are being checked have been obtained from an untrusted source this may lead to a Denial of Service.

The function DH_check() performs various checks on DH parameters. After fixing CVE-2023-3446 it was discovered that a large q parameter value can also trigger an overly long computation during some of these checks. A correct q value if present cannot be larger than the modulus p parameter thus it is unnecessary to perform these checks if q is larger than p.

An application that calls DH_check() and supplies a key or parameters obtained from an untrusted source could be vulnerable to a Denial of Service attack.

The function DH_check() is itself called by a number of other OpenSSL functions. An application calling any of those other functions may similarly be affected. The other functions affected by this are DH_check_ex() and EVP_PKEY_param_check().

Also vulnerable are the OpenSSL dhparam and pkeyparam command line applications when using the -check\ option.

The OpenSSL SSL/TLS implementation is not affected by this issue.

The OpenSSL 3.0 and 3.1 FIPS providers are not affected by this issue.

Reference

https://www.openssl.org/news/secadv/20230731.txt https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=6a1eb62c29db6cb5eec707f9338aee00f44e26f5 https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=9002fd07327a91f35ba6c1307e71fa6fd4409b7f https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=91ddeba0f2269b017dc06c46c993a788974b1aa5 https://git.openssl.org/gitweb/?p=openssl.git;a=commitdiff;h=869ad69aadd985c7b8ca6f4e5dd0eb274c9f3644 http://www.openwall.com/lists/oss-security/2023/07/31/1