CVE-2008-5023 in Firefox
Summary
by MITRE
Firefox 3.x before 3.0.4, Firefox 2.x before 2.0.0.18, and SeaMonkey 1.x before 1.1.13 allows remote attackers to bypass the protection mechanism for codebase principals and execute arbitrary script via the -moz-binding CSS property in a signed JAR file.
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Analysis
by VulDB Data Team • 08/20/2019
The vulnerability identified as CVE-2008-5023 represents a critical security flaw in Mozilla Firefox and SeaMonkey browsers that affects versions prior to specific patch releases. This vulnerability resides in the browser's handling of CSS properties and their interaction with signed JAR files, creating a path for remote attackers to circumvent security mechanisms designed to protect against cross-site scripting attacks. The flaw specifically targets the codebase principal protection mechanisms that are fundamental to browser security models, allowing malicious actors to execute arbitrary code with elevated privileges.
The technical implementation of this vulnerability exploits the -moz-binding CSS property, which is a proprietary Firefox feature designed to bind CSS to DOM elements for dynamic behavior. When a signed JAR file contains malicious CSS with the -moz-binding property, the browser's security model fails to properly validate the origin and integrity of the referenced resources. This allows attackers to load and execute arbitrary JavaScript code from within the context of the signed JAR file, effectively bypassing the security boundaries that should prevent such cross-origin code execution. The vulnerability operates at the intersection of CSS parsing, security principal management, and code signing validation, creating a complex attack surface that leverages multiple browser subsystems.
The operational impact of this vulnerability is severe as it enables remote code execution without requiring user interaction beyond visiting a malicious website. Attackers can craft malicious JAR files containing specially crafted CSS that, when loaded by an affected browser, executes arbitrary JavaScript code with the privileges of the signed application. This creates a significant risk for users who may encounter such malicious content through phishing attacks, compromised websites, or malicious advertisements. The vulnerability undermines the fundamental security model of browser sandboxing and code signing, potentially allowing attackers to access sensitive user data, perform actions on behalf of the user, or establish persistent backdoors.
Mitigation strategies for CVE-2008-5023 primarily focus on immediate software updates to patched versions of Firefox and SeaMonkey. Users should upgrade to Firefox 3.0.4, Firefox 2.0.0.18, or SeaMonkey 1.1.13 respectively, which contain fixes that properly validate CSS properties in signed JAR files and enforce stricter security boundaries. Security administrators should implement network-level controls to block access to known malicious domains and monitor for suspicious JAR file downloads. The vulnerability aligns with CWE-20, which describes improper input validation, and can be categorized under ATT&CK technique T1059 for command and scripting interpreter usage. Organizations should also consider implementing content security policies and restricting the use of potentially dangerous CSS properties in enterprise environments to reduce the attack surface.