CVE-2007-6592 in Safari
Summary
by MITRE
Apple Safari 2, when a user accepts an SSL server certificate on the basis of the CN domain name in the DN field, regards the certificate as also accepted for all domain names in subjectAltName:dNSName fields, which makes it easier for remote attackers to trick a user into accepting an invalid certificate for a spoofed web site.
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Analysis
by VulDB Data Team • 09/14/2018
This vulnerability in Apple Safari 2 represents a critical certificate validation flaw that undermines the fundamental security model of SSL/TLS communications. The issue stems from how Safari handles certificate verification when users manually accept certificates, creating a dangerous assumption that acceptance based on the Common Name field should extend to all subject alternative names. This behavior violates the established security principle that each certificate field should be validated independently, as outlined in the certificate validation standards defined by the x509v3 specification. The vulnerability creates a trust boundary violation where user acceptance of a certificate for one domain automatically extends to all domains listed in the subject alternative name fields, fundamentally weakening the certificate-based authentication mechanism.
The technical implementation flaw occurs at the certificate validation layer within Safari's security stack, where the browser's certificate acceptance logic fails to properly distinguish between the CN field and subjectAltName fields during user interaction. When a user manually accepts a certificate, Safari incorrectly assumes that acceptance of the Common Name field should implicitly validate all dNSName entries in the subject alternative name extension. This creates a certificate validation bypass that allows attackers to craft certificates with malicious domain names in the subjectAltName field while presenting a legitimate Common Name that users might accept. The vulnerability specifically affects Safari 2 and earlier versions, where the certificate validation code did not properly implement the standard certificate verification procedures that require explicit validation of each domain name field.
The operational impact of this vulnerability is significant for both individual users and enterprise environments, as it enables sophisticated phishing attacks and man-in-the-middle scenarios. Attackers can create certificates that appear legitimate to users who have previously accepted certificates for similar domains, allowing them to impersonate trusted websites without detection. This vulnerability enables what cybersecurity professionals classify as credential theft attacks and web application compromise techniques, as described in the attack patterns documented in the MITRE ATT&CK framework under the credential access and defense evasion domains. The flaw essentially allows attackers to bypass the certificate pinning mechanisms that users might have established, making it particularly dangerous in environments where users have accepted certificates for specific domains.
Security mitigations for this vulnerability require immediate browser updates to implement proper certificate validation logic that does not extend certificate acceptance across different domain name fields. Organizations should ensure that all Safari installations are updated to versions that properly validate each domain name field independently, as specified in the x509 certificate validation standards. Users should be educated about the importance of carefully reviewing certificate details before accepting them, and security teams should implement certificate monitoring systems to detect unusual certificate acceptance patterns. The vulnerability also highlights the importance of proper security testing for cryptographic implementations, as this flaw demonstrates the critical need for thorough validation of certificate acceptance logic in web browsers. Organizations should consider implementing additional security controls such as certificate transparency monitoring and automated certificate validation checking to prevent exploitation of similar vulnerabilities in other browser implementations. This vulnerability serves as a reminder of the critical importance of proper cryptographic implementation and the potential consequences of inadequate certificate validation procedures in security-critical applications.