CVE-2006-4567 in Firefox
Summary
by MITRE
Mozilla Firefox before 1.5.0.7 and Thunderbird before 1.5.0.7 makes it easy for users to accept self-signed certificates for the auto-update mechanism, which might allow remote user-assisted attackers to use DNS spoofing to trick users into visiting a malicious site and accepting a malicious certificate for the Mozilla update site, which can then be used to install arbitrary code on the next update.
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Analysis
by VulDB Data Team • 07/08/2019
This vulnerability resides in the certificate validation mechanisms of Mozilla Firefox and Thunderbird versions prior to 1.5.0.7, representing a critical security flaw that undermines the trust model of secure software updates. The issue specifically affects the auto-update functionality where the applications fail to properly enforce certificate validation requirements, creating an attack surface that malicious actors can exploit through DNS spoofing techniques. The vulnerability stems from the software's permissive handling of self-signed certificates during the update process, which allows attackers to present fraudulent certificates that appear legitimate to users. This weakness directly violates the fundamental principle of secure software distribution where certificate verification must be strict and non-negotiable to prevent man-in-the-middle attacks.
The technical exploitation of this vulnerability involves attackers leveraging DNS spoofing to redirect update requests to malicious servers hosting fraudulent certificates that mimic the legitimate Mozilla update infrastructure. When users attempt to update their browsers or email clients, they are presented with certificate warnings that the software's user interface design makes difficult to distinguish from legitimate security prompts. The flaw essentially creates a user experience where accepting self-signed certificates becomes trivial, bypassing the security controls that should prevent installation of malicious code. This vulnerability maps directly to CWE-295 which describes improper certificate validation and CWE-310 which covers cryptographic issues related to certificate validation.
The operational impact of this vulnerability extends far beyond simple certificate acceptance, as it enables attackers to establish persistent backdoors through legitimate update channels. Once a malicious certificate is accepted, attackers can deliver arbitrary code that executes during the next update cycle, effectively allowing for remote code execution and system compromise. The attack requires user interaction but leverages social engineering aspects through the auto-update mechanism, making it particularly dangerous as users are more likely to accept updates without scrutiny. This vulnerability represents a significant threat to enterprise environments where automated updates are common, as it can bypass traditional security controls and provide attackers with a reliable method for maintaining persistence.
Mitigation strategies for this vulnerability require immediate patching of affected software versions to implement proper certificate validation and reject self-signed certificates during the update process. Organizations should also implement network-level protections such as DNS filtering and certificate pinning to prevent DNS spoofing attacks. The fix addresses the core issue by enforcing strict certificate validation that requires certificates to be issued by trusted Certificate Authorities rather than accepting self-signed certificates. Security teams should monitor for exploitation attempts through network traffic analysis and implement user education programs to recognize suspicious certificate warnings. This vulnerability highlights the importance of maintaining secure update mechanisms and demonstrates how seemingly minor certificate validation flaws can lead to complete system compromise, aligning with ATT&CK technique T1059.007 which covers execution through command and script interpreters.