CVE-2022-1434: OpenSSL 3.0 RC4-MD5 MAC Key Vulnerability

CVE-2022-1434 Overview

CVE-2022-1434 is a cryptographic vulnerability in OpenSSL 3.0's implementation of the RC4-MD5 ciphersuite that incorrectly uses AAD (Additional Authenticated Data) as the MAC key. This implementation flaw makes the MAC key trivially predictable, allowing man-in-the-middle attackers to modify data in transit while bypassing MAC integrity checks.

Critical Impact

An attacker positioned between two endpoints can modify encrypted data being sent to an OpenSSL 3.0 recipient, and the modified data will still pass MAC integrity verification. When both endpoints are OpenSSL 3.0, bidirectional data modification is possible.

Affected Products

• OpenSSL 3.0.0, 3.0.1, 3.0.2
• NetApp Active IQ Unified Manager
• NetApp Clustered Data ONTAP
• NetApp Clustered Data ONTAP Antivirus Connector
• NetApp SolidFire Enterprise SDS & HCI Storage Node
• NetApp AFF/FAS Storage Systems (A250, AFF 500F, FAS 500F, AFF 8300, FAS 8300, AFF 8700, FAS 8700, AFF A400)
• NetApp H-Series Storage Systems (H300S, H500S, H700S, H300E, H500E, H700E, H410S, A700S)

Discovery Timeline

• May 3, 2022 - CVE-2022-1434 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2022-1434

Vulnerability Analysis

The OpenSSL 3.0 implementation of the RC4-MD5 ciphersuite contains a critical implementation error in its MAC (Message Authentication Code) key derivation process. Instead of using the properly derived cryptographic key material for MAC computation, the implementation incorrectly substitutes the AAD (Additional Authenticated Data) as the MAC key.

This substitution is problematic because AAD is transmitted in cleartext during the TLS handshake and is designed to be visible to all parties, including potential attackers. By using this publicly available data as the MAC key, the integrity protection mechanism becomes fundamentally compromised.

The vulnerability affects data integrity only—confidentiality remains intact because the actual encryption key is derived correctly. An attacker cannot decrypt the communications, but they can modify encrypted payloads and forge valid MAC tags that will be accepted by the recipient.

Root Cause

The root cause is an implementation error (CWE-327: Use of a Broken or Risky Cryptographic Algorithm) in OpenSSL 3.0's RC4-MD5 ciphersuite code where the AAD data is incorrectly assigned as the MAC key instead of the proper cryptographic key material. This makes the MAC key trivially predictable since AAD is transmitted in cleartext during the TLS handshake.

Attack Vector

For successful exploitation, the following conditions must all be met:

1. OpenSSL must be compiled with the non-default enable-weak-ssl-ciphers compile-time option
2. The legacy provider must be explicitly loaded via application code or configuration
3. The RC4-MD5 ciphersuite must be explicitly added to the ciphersuite list
4. The libssl security level must be set to 0 (default is 1)
5. A TLS version below TLSv1.3 must be negotiated
6. Both endpoints must negotiate RC4-MD5 in preference to other available ciphersuites

A man-in-the-middle attacker observing the TLS handshake can extract the AAD, which is used as the MAC key. The attacker can then intercept encrypted traffic, modify the ciphertext, and recalculate a valid MAC tag using the known key. The modified data will pass the integrity check at the recipient.

When an OpenSSL 3.0 endpoint communicates with a non-OpenSSL 3.0 endpoint, data sent from OpenSSL 3.0 will be rejected by the recipient (since they calculate MACs correctly), causing the connection to fail. However, data sent to the OpenSSL 3.0 endpoint can be modified by an attacker. When both endpoints are OpenSSL 3.0, bidirectional modification is possible.

Detection Methods for CVE-2022-1434

Indicators of Compromise

• TLS sessions negotiating the RC4-MD5 ciphersuite on OpenSSL 3.0 systems
• Unexpected connection failures between OpenSSL 3.0 and non-OpenSSL 3.0 endpoints using RC4-MD5
• OpenSSL configuration files with enable-weak-ssl-ciphers or legacy provider explicitly loaded
• Security level set to 0 in OpenSSL configuration

Detection Strategies

• Audit OpenSSL compilation flags to identify systems built with enable-weak-ssl-ciphers
• Monitor TLS handshakes for RC4-MD5 ciphersuite negotiation using network traffic analysis
• Review OpenSSL configuration files for legacy provider loading and security level modifications
• Implement TLS fingerprinting to detect deprecated ciphersuite usage across the environment

Monitoring Recommendations

• Deploy network monitoring to alert on any RC4-MD5 ciphersuite negotiation attempts
• Implement configuration management checks to ensure OpenSSL security level remains at default value of 1 or higher
• Monitor for man-in-the-middle indicators such as unexpected certificate changes or routing anomalies
• Audit application configurations that explicitly reference legacy ciphersuites

How to Mitigate CVE-2022-1434

Immediate Actions Required

• Upgrade OpenSSL to version 3.0.3 or later immediately
• Verify that systems are not compiled with the enable-weak-ssl-ciphers option
• Ensure the OpenSSL legacy provider is not explicitly loaded unless absolutely necessary
• Confirm security level is set to 1 or higher (the default)
• Enforce TLSv1.3 where possible to prevent vulnerable ciphersuite negotiation

Patch Information

OpenSSL has released version 3.0.3 which addresses this vulnerability. The fix corrects the MAC key derivation in the RC4-MD5 ciphersuite implementation. Affected versions include OpenSSL 3.0.0, 3.0.1, and 3.0.2. Organizations should refer to the OpenSSL Security Advisory for complete details and the OpenSSL commit for the specific code changes. NetApp users should consult NetApp Security Advisory NTAP-20220602-0009 for affected product updates.

Workarounds

• Do not compile OpenSSL with the enable-weak-ssl-ciphers option
• Avoid loading the legacy provider in OpenSSL configuration
• Explicitly exclude RC4-MD5 from the ciphersuite list in all TLS configurations
• Maintain the default security level of 1 or higher
• Enforce TLSv1.3 as the minimum protocol version where application compatibility permits

# OpenSSL configuration to disable weak ciphersuites
# Add to openssl.cnf or application configuration

# Ensure security level is at least 1 (default)
# ssl_conf = ssl_sect
# [ssl_sect]
# system_default = system_default_sect
# [system_default_sect]
# MinProtocol = TLSv1.2
# CipherString = DEFAULT:!RC4:!MD5:!aNULL:!eNULL
# Options = PrioritizeChaCha

# Verify OpenSSL version
openssl version
# Should show 3.0.3 or later

# Check ciphersuites to confirm RC4-MD5 is not enabled
openssl ciphers -v | grep -i rc4-md5
# Should return no results on properly configured systems