CVE-2007-6591 in Konqueror
Summary
by MITRE
KDE Konqueror 3.5.5 and 3.95.00, 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, even though these fields cannot be examined in the product, 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
The vulnerability identified as CVE-2007-6591 affects KDE Konqueror web browsers version 3.5.5 and 3.95.00, presenting a significant certificate validation flaw that undermines secure web communications. This issue stems from improper handling of SSL/TLS certificate verification processes where the browser accepts a certificate based solely on the Common Name field within the Distinguished Name structure, without properly examining the subjectAltName extension fields. The flaw creates a dangerous assumption that if a user accepts a certificate for one domain name, they have implicitly accepted it for all domains listed in the certificate's dNSName fields, even though the browser cannot actually display or verify these alternative names.
The technical implementation of this vulnerability demonstrates a failure in certificate validation logic that violates fundamental security principles established in PKI (Public Key Infrastructure) standards. When a user encounters an SSL certificate warning, Konqueror's certificate acceptance mechanism incorrectly extends trust from the Common Name field to all alternative names present in the subjectAltName extension, creating a false sense of security. This behavior essentially bypasses the proper certificate validation procedures that should require explicit verification of each domain name listed in the certificate's alternative names. The vulnerability represents a classic case of incomplete certificate validation where the browser fails to implement proper certificate chain verification, as outlined in x509 certificate standards and security best practices.
The operational impact of this vulnerability creates substantial risks for users engaging with web services, as it enables sophisticated man-in-the-middle attacks and certificate spoofing scenarios. Attackers can exploit this flaw by presenting certificates that match the Common Name but contain malicious alternative names in the subjectAltName field, potentially allowing them to intercept communications for domains the user might not even be aware are being targeted. This vulnerability aligns with attack patterns documented in the ATT&CK framework under credential access and defense evasion techniques, where attackers leverage browser implementation weaknesses to bypass security controls. The issue particularly affects users who rely on certificate warnings as security indicators, since the browser's behavior can lead to false confidence in certificate validity.
This vulnerability is classified as a weakness in certificate validation procedures and corresponds to CWE-295, which addresses improper certificate validation. The flaw demonstrates poor security implementation in the browser's SSL certificate handling mechanism, where the software fails to properly validate certificate contents against the expected domain names. Security researchers have noted that this type of vulnerability is particularly dangerous because it operates at the user interface level, where human trust decisions can be manipulated through technical implementation flaws. The vulnerability essentially creates a trust boundary violation where the browser's certificate acceptance logic fails to properly validate that the certificate actually applies to the domain the user is visiting, potentially leading to data interception and session hijacking attacks.
Mitigation strategies for this vulnerability require immediate browser updates to patched versions that properly implement certificate validation, ensuring that all alternative names in subjectAltName fields are verified against the target domain. Users should avoid accepting certificates based solely on Common Name fields and instead verify that certificates match the intended domain across all name fields. System administrators should implement certificate monitoring and validation procedures to detect potential exploitation attempts. The fix involves updating the browser's certificate validation logic to properly examine and validate all names present in certificate extensions, ensuring that acceptance of a certificate for one domain does not implicitly extend trust to other domains listed in alternative name fields. This represents a fundamental requirement for secure browser implementation that aligns with industry standards and security frameworks that emphasize proper certificate validation as a core security control.