CVE-2012-6461 in Web Browser
Summary
by MITRE
The X.509 certificate-validation functionality in the https implementation in Opera before 12.10 allows remote attackers to trigger a false indication of successful revocation-status checking by causing a failure of a single checking service.
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Analysis
by VulDB Data Team • 12/29/2024
The vulnerability identified as CVE-2012-6461 resides within Opera's implementation of X.509 certificate validation mechanisms for HTTPS connections, affecting versions prior to 12.10. This flaw represents a critical weakness in the browser's certificate revocation checking process that undermines the security assurances typically provided by certificate validation protocols. The vulnerability specifically targets the certificate revocation status checking functionality, which is essential for verifying that digital certificates have not been compromised or revoked by their issuing authorities.
The technical flaw manifests when a single certificate revocation checking service fails or becomes unavailable during the validation process. Opera's implementation incorrectly interprets this service failure as a successful revocation check, thereby allowing certificates that should be marked as invalid to be accepted as legitimate. This behavior violates fundamental security principles of certificate validation where multiple independent sources should be consulted, and failure of one source should not lead to false positive results. The vulnerability stems from inadequate error handling and logic flow in the certificate validation code, where service unavailability is incorrectly processed as a successful validation outcome rather than a validation failure requiring alternative checking methods.
Operationally, this vulnerability creates a significant risk for users connecting to websites that rely on proper certificate validation for secure communications. Attackers can exploit this weakness by targeting specific certificate revocation services, causing them to fail or become unavailable, which then results in the browser accepting compromised certificates that should have been rejected. This allows for man-in-the-middle attacks where malicious actors can present certificates that appear valid to the browser but are actually compromised or fraudulent. The impact extends beyond individual user sessions to potentially enable large-scale security breaches where attackers can impersonate legitimate websites without detection, undermining the trust model that HTTPS and X.509 certificates are designed to provide.
The vulnerability aligns with CWE-252, which describes "Unchecked Return Value" in security contexts, where the system fails to properly validate or handle return values from critical security functions. Additionally, this weakness maps to ATT&CK technique T1552.001, "Credentials in Files," as it enables attackers to bypass certificate validation mechanisms that would otherwise prevent unauthorized access to secure resources. The flaw demonstrates poor adherence to security best practices for certificate validation, where systems should implement redundant checking mechanisms and fail securely rather than accepting potentially compromised certificates. Organizations should immediately upgrade to Opera version 12.10 or later, and implement additional monitoring for certificate validation failures to detect potential exploitation attempts. Network administrators should also consider implementing certificate pinning strategies and additional certificate monitoring solutions to provide defense-in-depth against this specific vulnerability and similar certificate validation weaknesses.