CVE-2022-29242 is a medium-severity vulnerability classified under CWE-120, indicating a classic buffer overflow issue in the gost-engine, which is a reference implementation of Russian GOST cryptographic algorithms for OpenSSL. The vulnerability specifically affects TLS clients that utilize the gost-engine when negotiating the ciphersuite TLS_GOSTR341112_256_WITH_KUZNYECHIK_CTR_OMAC and when the server employs 512-bit GOST secret keys. The root cause is a buffer copy operation that does not properly check the size of the input, leading to a potential overflow. This flaw exists in versions of gost-engine prior to 3.0.1, which contains a patch addressing this issue. The vulnerability can be mitigated by disabling the affected ciphersuite as a workaround if patching is not immediately feasible. Exploitation of this vulnerability could allow an attacker to cause memory corruption, potentially leading to arbitrary code execution or denial of service on the TLS client. However, no known exploits have been reported in the wild to date. The vulnerability requires the client to negotiate the specific vulnerable ciphersuite with a server using 512-bit keys, which limits the attack surface somewhat. The vulnerability impacts confidentiality, integrity, and availability due to the possibility of arbitrary code execution or crashes. The flaw does not require user interaction but does require the client to connect to a malicious or compromised server that supports the vulnerable ciphersuite and key size. The scope is limited to systems using the vulnerable gost-engine versions and the specific ciphersuite configuration.

For European organizations, the impact of CVE-2022-29242 depends largely on the adoption of the gost-engine and the use of the affected ciphersuite. Organizations that rely on OpenSSL with the gost-engine for cryptographic operations, particularly those engaging in communications with Russian entities or using Russian cryptographic standards, are at risk. Successful exploitation could lead to client-side compromise, including arbitrary code execution or denial of service, potentially allowing attackers to intercept or manipulate sensitive communications. This is particularly concerning for sectors handling sensitive data such as government, defense, critical infrastructure, and financial services. The vulnerability could undermine the confidentiality and integrity of TLS sessions, impacting secure communications. Given the specificity of the vulnerability to the GOST ciphersuite and 512-bit keys, the overall risk to the broader European IT environment is moderate but non-negligible in targeted scenarios. Additionally, the lack of known exploits reduces immediate risk but does not eliminate the threat, especially as threat actors may develop exploits over time.

1. Upgrade gost-engine to version 3.0.1 or later, which contains the patch for this vulnerability. 2. If immediate patching is not possible, disable the TLS ciphersuite TLS_GOSTR341112_256_WITH_KUZNYECHIK_CTR_OMAC in OpenSSL configurations to prevent negotiation of the vulnerable cryptographic parameters. 3. Conduct an inventory of systems using gost-engine to identify affected clients and servers. 4. Monitor TLS handshake logs to detect any attempts to negotiate the vulnerable ciphersuite, which could indicate scanning or exploitation attempts. 5. Implement network-level controls to restrict connections to untrusted or unknown servers that might attempt to exploit this vulnerability. 6. For organizations with high security requirements, consider auditing cryptographic libraries and configurations to ensure no legacy or unsupported cryptographic algorithms are in use. 7. Educate security teams about this specific vulnerability to ensure rapid response if exploitation attempts are detected. 8. Regularly update OpenSSL and related cryptographic components to benefit from security patches and improvements.