CVE-2009-1835 in Firefox
Summary
by MITRE
Mozilla Firefox before 3.0.11 and SeaMonkey before 1.1.17 associate local documents with external domain names located after the file:// substring in a URL, which allows user-assisted remote attackers to read arbitrary cookies via a crafted HTML document, as demonstrated by a URL with file://example.com/C:/ at the beginning.
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Analysis
by VulDB Data Team • 09/06/2019
This vulnerability exists in Mozilla Firefox versions prior to 3.0.11 and SeaMonkey versions prior to 1.1.17 due to improper handling of file URLs that contain domain names following the file:// protocol identifier. The flaw stems from a lack of proper validation and sanitization of file path components within URLs, creating a path traversal condition that can be exploited by remote attackers. When a malicious HTML document contains a crafted URL with file://example.com/C:/ at the beginning, the browser incorrectly processes the domain name portion as part of the file path rather than as a separate domain component. This misinterpretation allows attackers to construct URLs that bypass normal security boundaries and access local system resources.
The technical implementation of this vulnerability involves the browser's URL parsing mechanism failing to properly separate the file protocol identifier from subsequent domain information. Specifically, when Firefox encounters a URL such as file://example.com/C:/path/to/file, it incorrectly treats example.com as part of the file system path rather than as a network domain. This parsing error enables attackers to craft malicious documents that can access local files and potentially extract sensitive information. The vulnerability is classified under CWE-22 as a path traversal weakness, where attacker-controllable input is used to access files outside the intended directory structure. The issue represents a fundamental flaw in the browser's URI handling and access control mechanisms, allowing arbitrary file access through carefully constructed URLs.
The operational impact of this vulnerability is significant as it enables remote attackers to perform cookie theft and unauthorized file access on compromised systems. An attacker can craft HTML documents that, when viewed by a victim using an affected browser, will attempt to read local files including browser cookies, cached data, and other sensitive information stored on the victim's machine. This creates a serious privacy and security risk, as it allows attackers to potentially hijack user sessions, steal authentication tokens, and access personal data stored locally. The vulnerability is particularly dangerous because it requires only user interaction with a malicious webpage, making it a classic example of a user-assisted remote attack vector. The attack can be executed through various means including phishing emails, compromised websites, or malicious advertisements that direct users to exploit the vulnerability.
Mitigation strategies for this vulnerability involve updating to patched versions of Firefox and SeaMonkey where the URL parsing logic has been corrected to properly separate file protocol components from domain information. Users should immediately upgrade to Firefox 3.0.11 or later and SeaMonkey 1.1.17 or later, which contain the necessary security fixes. System administrators should implement network-level protections such as web application firewalls and content filtering systems to block access to known malicious domains. Additionally, users should exercise caution when visiting untrusted websites and avoid clicking on suspicious links or downloading unknown files. The vulnerability demonstrates the importance of proper input validation and secure parsing of user-controllable data, particularly in web browsers where security boundaries are critical for protecting user privacy and system integrity. Organizations should also consider implementing security awareness training to help users recognize potential phishing attempts that may exploit such vulnerabilities.