CVE-2013-5606 in Network Security Services
Summary
by MITRE
The CERT_VerifyCert function in lib/certhigh/certvfy.c in Mozilla Network Security Services (NSS) 3.15 before 3.15.3 provides an unexpected return value for an incompatible key-usage certificate when the CERTVerifyLog argument is valid, which might allow remote attackers to bypass intended access restrictions via a crafted certificate.
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Analysis
by VulDB Data Team • 06/02/2021
The vulnerability identified as CVE-2013-5606 resides within Mozilla Network Security Services (NSS) version 3.15 and earlier, specifically within the CERT_VerifyCert function located in lib/certhigh/certvfy.c. This flaw represents a critical security issue that undermines the certificate validation process, potentially allowing malicious actors to circumvent intended access controls. The vulnerability manifests when the function encounters a certificate with incompatible key usage, yet provides an unexpected return value that does not properly reject such certificates. This behavior creates a scenario where certificates that should be deemed invalid due to key usage mismatches are incorrectly accepted by the system.
The technical nature of this vulnerability stems from improper certificate validation logic within the NSS library, which is a fundamental component of Mozilla's security infrastructure. When CERTVerifyLog argument is valid but encounters a certificate with incompatible key usage, the function fails to properly enforce the certificate validation rules. This misbehavior allows attackers to craft certificates that contain key usage extensions incompatible with their intended purpose yet still pass validation checks. The vulnerability specifically affects the certificate verification process where key usage constraints are not properly enforced, creating a bypass mechanism for access restrictions that should normally prevent such certificates from being accepted.
From an operational impact perspective, this vulnerability enables remote attackers to perform certificate-based attacks that could compromise secure communications and authentication systems. The ability to bypass key usage restrictions means that malicious actors could potentially use certificates with inappropriate key usage extensions to gain unauthorized access to systems or services that rely on proper certificate validation. This weakness particularly affects applications and systems that depend on NSS for secure communication, potentially allowing attackers to impersonate legitimate services or bypass authentication mechanisms that should prevent unauthorized access.
The vulnerability aligns with CWE-295 which addresses improper certificate validation and certificate pinning issues, and it relates to ATT&CK technique T1552.001 which covers credentials from password storage providers. Organizations using NSS versions prior to 3.15.3 face significant risk as this flaw could be exploited to undermine the entire certificate trust model. The impact extends beyond simple certificate acceptance to potentially compromise the integrity of secure communication channels and authentication systems that rely on proper certificate validation.
Mitigation strategies for CVE-2013-5606 require immediate upgrade to NSS version 3.15.3 or later, which contains the necessary fixes to properly enforce key usage validation. System administrators should also implement additional monitoring for certificate validation failures and ensure that certificate authorities properly enforce key usage constraints. Organizations should conduct thorough security assessments of systems relying on NSS to identify potential exploitation vectors and implement proper certificate management practices. The fix addresses the core validation logic to ensure that incompatible key usage certificates are properly rejected, restoring the intended security controls that prevent unauthorized access through malformed certificates.