CVE-2007-3845 in Thunderbird
Summary
by MITRE
Mozilla Firefox before 2.0.0.6, Thunderbird before 1.5.0.13 and 2.x before 2.0.0.6, and SeaMonkey before 1.1.4 allow remote attackers to execute arbitrary commands via certain vectors associated with launching "a file handling program based on the file extension at the end of the URI," a variant of CVE-2007-4041. NOTE: the vendor states that "it is still possible to launch a filetype handler based on extension rather than the registered protocol handler."
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 07/23/2019
This vulnerability represents a critical file handling flaw in Mozilla Firefox, Thunderbird, and SeaMonkey browsers that existed prior to specific version releases. The vulnerability stems from how these applications process URIs that contain file extensions, creating a pathway for remote code execution through improper validation of file type handlers. The flaw specifically affects versions where the software continues to rely on file extension-based protocol handling rather than properly registered protocol handlers, creating an attack surface that malicious actors can exploit. This issue is particularly concerning because it allows remote attackers to execute arbitrary commands on affected systems simply by crafting malicious URIs that trigger the vulnerable file handling mechanisms.
The technical implementation of this vulnerability involves the browser's inability to properly sanitize or validate URI schemes that contain file extensions, leading to a situation where the application may execute unintended file handling programs based on the extension rather than the proper protocol registration. This behavior creates a direct pathway for command injection attacks, as the system will launch programs associated with specific file extensions without proper verification of the source or legitimacy of the request. The vulnerability operates at the application layer and can be exploited through web-based attacks, requiring no special privileges from the attacker beyond the ability to deliver malicious content to a victim's browser.
From an operational impact perspective, this vulnerability enables remote code execution attacks that can compromise entire user systems, potentially allowing attackers to install malware, steal sensitive data, or perform other malicious activities. The attack vector is particularly dangerous because it can be delivered through standard web browsing activities, making it difficult for users to protect themselves without updating their software. The vulnerability affects not just individual browsers but also email clients that use the same underlying engine, amplifying the potential attack surface significantly. Organizations using these affected versions face substantial risk of compromise, particularly in environments where users frequently browse untrusted websites or receive email from unknown sources.
The mitigation strategy for this vulnerability requires immediate software updates to the patched versions mentioned in the advisory, specifically Firefox 2.0.0.6, Thunderbird 1.5.0.13 and 2.0.0.6, and SeaMonkey 1.1.4. Security administrators should also implement network-level protections such as web application firewalls and content filtering systems to block suspicious URI patterns. Additionally, user education regarding the dangers of visiting untrusted websites and opening email attachments is crucial. Organizations should also consider implementing browser hardening measures, including disabling automatic file handling for unknown extensions and configuring browsers to use more secure protocol handling mechanisms. This vulnerability aligns with CWE-78 and CWE-88 categories related to command injection and improper input validation, and maps to ATT&CK techniques involving exploitation of software vulnerabilities and command and control communications. The persistent nature of this issue, as noted by the vendor, indicates that organizations must remain vigilant about the continued risk of extension-based protocol handling even after initial patches are applied.