CVE-2017-5381 in Firefox
Summary
by MITRE
The "export" function in the Certificate Viewer can force local filesystem navigation when the "common name" in a certificate contains slashes, allowing certificate content to be saved in unsafe locations with an arbitrary filename. This vulnerability affects Firefox < 51.
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Analysis
by VulDB Data Team • 11/04/2022
The vulnerability described in CVE-2017-5381 represents a critical file system traversal issue within Firefox's certificate viewer functionality. This flaw exists in the handling of certificate export operations where the application fails to properly sanitize the common name field from X.509 certificates before using it to construct file paths. When a certificate contains forward slashes in its common name field, the export function interprets these characters as directory separators, potentially allowing an attacker to manipulate the file system location where certificate data is saved. The vulnerability specifically impacts Firefox versions prior to 51, making it a significant concern for users running outdated browser software.
The technical implementation of this vulnerability stems from improper input validation and path construction practices within the certificate export mechanism. When users attempt to export certificates through Firefox's certificate viewer, the application processes the common name field without adequate sanitization or path validation. This creates an opportunity for path traversal attacks where maliciously crafted certificate data can cause the browser to write files to arbitrary locations on the local file system. The issue is classified under CWE-22, which specifically addresses path traversal vulnerabilities, and represents a classic example of insecure direct object reference where user-supplied data directly influences file system operations.
The operational impact of this vulnerability extends beyond simple file system manipulation, as it could enable attackers to overwrite critical system files or place malicious content in strategic locations. An attacker could craft a certificate with a common name containing directory traversal sequences such as "../" or "../../../" to navigate outside of intended directories and write files to system locations where they might execute with elevated privileges or interfere with normal system operations. This vulnerability could be exploited in conjunction with other attack vectors, potentially allowing for privilege escalation or persistent access to compromised systems. The ATT&CK framework categorizes this under T1059 Command and Scripting Interpreter and T1074 Data Staged, as it enables attackers to manipulate system files and potentially establish persistence through crafted certificate content.
Mitigation strategies for this vulnerability require immediate software updates to Firefox version 51 or later, where the certificate export functionality has been properly patched to sanitize input fields before constructing file paths. Organizations should implement comprehensive patch management procedures to ensure all browser installations remain current with security updates. Additionally, system administrators should consider implementing file system access controls and monitoring for unauthorized file system modifications, particularly in directories where certificate data might be processed. The vulnerability demonstrates the importance of proper input validation and secure coding practices, particularly when handling user-supplied data in file system operations. Regular security assessments and code reviews focusing on path handling and input sanitization can help prevent similar vulnerabilities in other applications and systems.