CVE-2012-0477 in Firefox
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in Mozilla Firefox 4.x through 11.0, Firefox ESR 10.x before 10.0.4, Thunderbird 5.0 through 11.0, Thunderbird ESR 10.x before 10.0.4, and SeaMonkey before 2.9 allow remote attackers to inject arbitrary web script or HTML via the (1) ISO-2022-KR or (2) ISO-2022-CN character set.
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Analysis
by VulDB Data Team • 10/21/2024
The vulnerability identified as CVE-2012-0477 represents a critical cross-site scripting weakness affecting multiple Mozilla products including Firefox, Thunderbird, and SeaMonkey across several versions. This vulnerability stems from improper handling of specific character encodings, specifically ISO-2022-KR and ISO-2022-CN, which are used to represent text in various international languages. The flaw exists in the browser's character set processing mechanisms that fail to properly sanitize input when these particular encoding standards are encountered during web page rendering. This issue falls under CWE-79 which specifically addresses cross-site scripting vulnerabilities, and aligns with ATT&CK technique T1059.001 for command and scripting interpreter execution through web-based attacks.
The technical implementation of this vulnerability occurs when web content is processed using the affected character sets, allowing attackers to inject malicious scripts that execute within the context of the victim's browser session. The exploitation mechanism leverages the fact that these specific character encodings contain sequences that can be manipulated to bypass normal input validation checks. When the browser encounters malformed or specially crafted ISO-2022-KR or ISO-2022-CN encoded content, it fails to properly isolate the malicious payload from legitimate content, resulting in script execution. The vulnerability is particularly concerning because these character sets are commonly used in web applications, making the attack surface broad and accessible to remote threat actors.
Operational impact of this vulnerability extends beyond simple script injection, as it can enable attackers to perform session hijacking, steal sensitive user data, redirect users to malicious websites, or execute arbitrary commands within the victim's browser context. The affected versions represent a significant portion of the user base at the time of discovery, making this vulnerability particularly dangerous for organizations relying on these browsers. The remote nature of the attack means that users can be compromised simply by visiting malicious websites or receiving crafted email content in Thunderbird, without requiring any special privileges or user interaction beyond normal browsing behavior. This vulnerability directly impacts the principle of least privilege and can lead to complete browser compromise.
Mitigation strategies for CVE-2012-0477 primarily involve immediate software updates to patched versions of the affected applications. Users should upgrade to Firefox 11.0.4, Firefox ESR 10.0.4, Thunderbird 11.0.4, Thunderbird ESR 10.0.4, and SeaMonkey 2.9 or later. System administrators should implement network-based filtering to block suspicious content and monitor for unusual character encoding patterns in web traffic. Additional protective measures include enabling strict content security policies, implementing proper input validation at network boundaries, and educating users about the risks of visiting untrusted websites. Organizations should also consider implementing web application firewalls and regular security assessments to identify similar encoding-related vulnerabilities that may exist in their browser configurations. The remediation process should include thorough testing of patched versions to ensure compatibility while maintaining security posture.