CVE-2004-0759 in Mozilla
Summary
by MITRE
Mozilla before 1.7 allows remote web servers to read arbitrary files via Javascript that sets the value of an <input type="file"> tag.
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Analysis
by VulDB Data Team • 06/30/2021
The vulnerability identified as CVE-2004-0759 represents a significant security flaw in the Mozilla browser family prior to version 1.7, specifically addressing a cross-site scripting and privilege escalation issue. This vulnerability exploits a fundamental weakness in how the browser handles file input elements, creating an unexpected pathway for malicious web servers to access local system resources. The flaw resides in the browser's implementation of the HTML input type="file" element, which should normally restrict file access to user-selected files through the browser's file picker interface. However, the vulnerability allows remote web servers to programmatically set arbitrary file paths through javascript manipulation, effectively bypassing normal security boundaries between the browser's sandboxed environment and the underlying operating system.
The technical exploitation of this vulnerability occurs through javascript code that manipulates the value attribute of file input elements. When a remote web server injects malicious javascript into a webpage, it can directly set the value of an <input type="file"> element to any filesystem path accessible to the browser process. This capability enables attackers to read files from the local system that would normally be protected from web-based access, including configuration files, user data, and potentially sensitive system information. The vulnerability essentially removes the sandboxing protections that should prevent web content from accessing local filesystem resources without explicit user interaction. This flaw aligns with CWE-22, which describes improper limitation of a pathname to a restricted directory, and represents a classic example of privilege escalation through improper input validation.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can enable more sophisticated attacks that leverage the ability to read local files. Attackers could potentially access browser configuration files, cached data, cookies, or other sensitive information stored locally on the victim's system. The vulnerability is particularly dangerous because it requires no user interaction beyond visiting a malicious webpage, making it a passive threat that can be exploited at scale. The attack vector demonstrates a breakdown in the browser's security model, where web content can bypass the normal file access controls that protect users from unauthorized system access. This vulnerability contributes to the broader category of attacks described in the ATT&CK framework under T1059.007 for JavaScript execution and T1074 for data staging, where attackers establish initial access through web-based exploitation and then move laterally within the compromised system.
Mitigation strategies for this vulnerability require immediate browser updates to versions that properly implement security boundaries for file input elements. The fix typically involves implementing stricter validation of file input values, ensuring that javascript cannot programmatically set file paths outside of user-controlled contexts. Security researchers recommend that browser vendors implement comprehensive input sanitization for all file-related operations and establish clear boundaries between web content and local filesystem access. Organizations should also deploy network-based security controls such as web application firewalls and content filtering systems to detect and block malicious javascript payloads. The vulnerability underscores the importance of maintaining current browser versions and implementing robust security practices around web content execution, as it demonstrates how seemingly benign HTML elements can be exploited to create serious security breaches. Additionally, user education regarding the risks of visiting untrusted websites and the importance of keeping software updated remains crucial in defending against such attacks.