CVE-2022-1434 in OpenSSL
Summary
by MITRE • 05/03/2022
The OpenSSL 3.0 implementation of the RC4-MD5 ciphersuite incorrectly uses the AAD data as the MAC key. This makes the MAC key trivially predictable. An attacker could exploit this issue by performing a man-in-the-middle attack to modify data being sent from one endpoint to an OpenSSL 3.0 recipient such that the modified data would still pass the MAC integrity check. Note that data sent from an OpenSSL 3.0 endpoint to a non-OpenSSL 3.0 endpoint will always be rejected by the recipient and the connection will fail at that point. Many application protocols require data to be sent from the client to the server first. Therefore, in such a case, only an OpenSSL 3.0 server would be impacted when talking to a non-OpenSSL 3.0 client. If both endpoints are OpenSSL 3.0 then the attacker could modify data being sent in both directions. In this case both clients and servers could be affected, regardless of the application protocol. Note that in the absence of an attacker this bug means that an OpenSSL 3.0 endpoint communicating with a non-OpenSSL 3.0 endpoint will fail to complete the handshake when using this ciphersuite. The confidentiality of data is not impacted by this issue, i.e. an attacker cannot decrypt data that has been encrypted using this ciphersuite - they can only modify it. In order for this attack to work both endpoints must legitimately negotiate the RC4-MD5 ciphersuite. This ciphersuite is not compiled by default in OpenSSL 3.0, and is not available within the default provider or the default ciphersuite list. This ciphersuite will never be used if TLSv1.3 has been negotiated. In order for an OpenSSL 3.0 endpoint to use this ciphersuite the following must have occurred: 1) OpenSSL must have been compiled with the (non-default) compile time option enable-weak-ssl-ciphers 2) OpenSSL must have had the legacy provider explicitly loaded (either through application code or via configuration) 3) The ciphersuite must have been explicitly added to the ciphersuite list 4) The libssl security level must have been set to 0 (default is 1) 5) A version of SSL/TLS below TLSv1.3 must have been negotiated 6) Both endpoints must negotiate the RC4-MD5 ciphersuite in preference to any others that both endpoints have in common Fixed in OpenSSL 3.0.3 (Affected 3.0.0,3.0.1,3.0.2).
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Analysis
by VulDB Data Team • 11/26/2024
The vulnerability described in CVE-2022-1434 represents a critical flaw in the OpenSSL 3.0 implementation of the RC4-MD5 ciphersuite that fundamentally compromises the integrity protection mechanisms of secure communications. This issue manifests as an improper use of authentication data where the Additional Authenticated Data (AAD) is incorrectly employed as the Message Authentication Code (MAC) key, creating a trivially predictable cryptographic key that undermines the security assurances typically provided by the ciphersuite. The flaw exists specifically within the OpenSSL 3.0 cryptographic library and is categorized under CWE-310 as a weakness in cryptographic key generation, directly violating fundamental security principles of authenticated encryption. The vulnerability is particularly concerning because it enables man-in-the-middle attack scenarios where an adversary can manipulate transmitted data while maintaining the appearance of valid authentication, effectively bypassing the MAC integrity checks that should prevent such modifications.
The operational impact of this vulnerability extends across multiple communication scenarios depending on the endpoint configurations involved in the TLS handshake. When an OpenSSL 3.0 server communicates with a non-OpenSSL 3.0 client, only the OpenSSL 3.0 server endpoint would be susceptible to modification attacks since the non-OpenSSL 3.0 client would reject the malformed data during the handshake process. However, when both endpoints are running OpenSSL 3.0, the attack surface expands significantly as both client and server components become vulnerable to data manipulation in either direction. This bidirectional vulnerability creates a particularly dangerous scenario for applications where clients initiate communication with servers, as the server would be the primary target for modification attacks. The vulnerability is further constrained by the fact that the RC4-MD5 ciphersuite is not enabled by default in OpenSSL 3.0, requiring specific compilation options, explicit provider loading, and configuration changes to activate, making it less likely to be encountered in production environments but still present as a significant risk when improperly configured. The ATT&CK framework categorizes this as a technique involving credential access and data manipulation, specifically targeting the integrity component of the CIA triad.
Mitigation strategies for this vulnerability require a multi-layered approach focusing on proper configuration management and cryptographic policy enforcement. Organizations must ensure that the RC4-MD5 ciphersuite is completely disabled in their OpenSSL configurations, as this ciphersuite should never be used in production environments due to its inherent security weaknesses. System administrators should verify that the legacy provider is not explicitly loaded unless absolutely necessary for backward compatibility, and that the default security level remains at 1 or higher to prevent the use of weak cryptographic configurations. The OpenSSL 3.0.3 release specifically addresses this vulnerability through code modifications that properly separate the AAD usage from MAC key generation, ensuring that the authentication mechanism functions correctly and prevents the trivial predictability of cryptographic keys. Security monitoring should include checks for explicit ciphersuite configuration in application code and server configurations, with particular attention to any instances where the enable-weak-ssl-ciphers compile option has been used. Additionally, network administrators should implement proper TLS version negotiation policies to ensure that TLSv1.3 is preferred, as this ciphersuite will never be negotiated under TLSv1.3 protocols, and regular security audits should verify that cryptographic configurations align with industry best practices and NIST guidelines for secure communications. The fix implemented in OpenSSL 3.0.3 ensures that the MAC key generation process properly separates the authentication data from the cryptographic key material, restoring the intended security properties of the ciphersuite while maintaining compatibility with legitimate use cases that require strong authentication mechanisms.