CVE-2023-5594 in NOD32 Antivirus
Summary
by MITRE • 12/21/2023
Improper validation of the server’s certificate chain in secure traffic scanning feature considered intermediate certificate signed using the MD5 or SHA1 algorithm as trusted.
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Analysis
by VulDB Data Team • 01/14/2024
This vulnerability resides in the secure traffic scanning functionality of affected systems where the certificate validation process fails to properly verify the cryptographic strength of intermediate certificates within the certificate chain. The flaw specifically allows the system to accept certificates that utilize weak hashing algorithms such as MD5 or SHA1 for signing intermediate certificates, despite these algorithms being considered cryptographically insecure. This represents a critical weakness in the certificate trust model where the system's validation logic does not adequately enforce cryptographic algorithm strength requirements. The vulnerability stems from insufficient implementation of certificate chain validation protocols that should enforce minimum cryptographic security standards. According to the CWE database, this issue maps to CWE-310 which addresses cryptographic weakness in certificate validation processes. The security implications extend beyond simple certificate validation as this weakness creates a potential attack vector for man-in-the-middle scenarios where adversaries could exploit the trust of weakly signed intermediate certificates to compromise secure communications.
The technical flaw manifests in the certificate chain validation algorithm which appears to perform basic certificate path validation but omits crucial cryptographic strength checks. When a certificate chain is processed, the system evaluates the trustworthiness of each certificate in the chain including intermediate certificates. However, the validation logic fails to properly check whether intermediate certificates were signed using secure hashing algorithms, specifically rejecting the use of MD5 or SHA1 which have known cryptographic weaknesses. This vulnerability aligns with ATT&CK technique T1552.001 which covers credentials in files and T1046 which involves network service scanning. The system's failure to enforce cryptographic algorithm strength requirements creates a trust boundary violation where the security model accepts certificates that should be rejected due to their weak cryptographic foundation.
The operational impact of this vulnerability is significant as it undermines the fundamental security guarantees provided by certificate-based authentication systems. Attackers could potentially generate or obtain intermediate certificates signed with MD5 or SHA1 algorithms and use them to establish fraudulent secure connections that would be accepted by the vulnerable system. This creates a scenario where legitimate security controls are bypassed, allowing unauthorized access to protected resources. The vulnerability affects the integrity of secure communications by enabling certificate forgery attacks that exploit the trust model's weakness in cryptographic validation. Organizations relying on secure traffic scanning for network monitoring or web filtering would face potential exposure to data interception and unauthorized access. The impact extends to compliance requirements as many regulatory frameworks mandate the use of strong cryptographic algorithms for secure communications, making this vulnerability a violation of security standards.
Mitigation strategies should focus on implementing strict cryptographic algorithm validation within certificate chain processing. Organizations must ensure that certificate validation logic enforces minimum cryptographic strength requirements that prohibit the acceptance of certificates signed with MD5 or SHA1 algorithms. This includes updating certificate validation libraries and implementing proper certificate pinning mechanisms where appropriate. System administrators should conduct thorough certificate chain validation testing to identify and remediate any weak certificate signatures within existing trust chains. The implementation of certificate validation policies should align with industry standards such as those specified in NIST SP 800-57 for cryptographic key management and NIST SP 800-131A for cryptographic algorithm migration. Regular security assessments should verify that certificate validation processes properly enforce cryptographic strength requirements and that intermediate certificates meet minimum security standards. Additionally, organizations should implement monitoring solutions to detect and alert on any attempts to establish connections using certificates with weak cryptographic signatures, providing visibility into potential exploitation attempts.