CVE-2012-0451 in Firefox
Summary
by MITRE
CRLF injection vulnerability in Mozilla Firefox 4.x through 10.0, Firefox ESR 10.x before 10.0.3, Thunderbird 5.0 through 10.0, Thunderbird ESR 10.x before 10.0.3, and SeaMonkey before 2.8 allows remote web servers to bypass intended Content Security Policy (CSP) restrictions and possibly conduct cross-site scripting (XSS) attacks via crafted HTTP headers.
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Analysis
by VulDB Data Team • 10/21/2024
The CVE-2012-0451 vulnerability represents a critical CRLF injection flaw affecting multiple Mozilla products including Firefox, Thunderbird, and SeaMonkey across specific version ranges. This vulnerability stems from improper handling of carriage return line feed sequences in HTTP headers, creating a pathway for malicious web servers to manipulate browser behavior and bypass security controls. The flaw specifically impacts versions 4.x through 10.0 of Firefox, 5.0 through 10.0 of Thunderbird, and versions prior to 2.8 of SeaMonkey, with corresponding ESR releases having separate patch versions. The technical implementation involves the browser's failure to adequately sanitize or validate HTTP header content, allowing attackers to inject additional headers that can alter the browser's interpretation of security policies and content delivery.
This vulnerability operates at the HTTP protocol level where CRLF sequences are used to separate header fields and terminate requests. When a vulnerable browser processes HTTP headers containing crafted CRLF sequences, it can be tricked into interpreting additional header data as part of the original request. The impact extends beyond simple header manipulation as it directly undermines Content Security Policy enforcement mechanisms that browsers rely on to prevent XSS attacks. The vulnerability creates a condition where attackers can inject malicious headers that bypass CSP restrictions, potentially allowing execution of unauthorized scripts or manipulation of content delivery. According to CWE-115, this represents a weakness in data handling where the application does not properly distinguish between data and control information, enabling attackers to inject control sequences that alter program flow.
The operational impact of CVE-2012-0451 is significant as it enables sophisticated attack scenarios that can bypass multiple layers of security. Remote web servers can exploit this vulnerability to inject malicious headers that modify how browsers process content, effectively allowing attackers to circumvent security controls designed to prevent XSS attacks. The vulnerability can be leveraged to inject malicious JavaScript code into web pages, redirect users to malicious sites, or manipulate the browser's security context in ways that compromise user data and system integrity. Attackers can craft HTTP responses that include CRLF sequences in header fields, causing the browser to interpret additional headers that might include script tags, redirect instructions, or other malicious content. This vulnerability particularly affects web applications that rely on CSP for XSS protection and demonstrates how low-level protocol handling issues can create widespread security implications across multiple browser implementations.
Organizations should implement immediate mitigation strategies including updating to patched versions of affected software, implementing network-level protections such as web application firewalls, and monitoring for suspicious header patterns in HTTP traffic. The vulnerability aligns with ATT&CK technique T1059.007 for script injection and T1566 for phishing attacks, as it enables attackers to bypass security controls and inject malicious content. Security teams should also consider implementing strict header validation policies and monitoring for anomalous HTTP header sequences that might indicate exploitation attempts. The patching process for this vulnerability required careful coordination across multiple Mozilla products and release channels, demonstrating the complexity of addressing protocol-level vulnerabilities in widely deployed software. Organizations using older versions of these browsers should prioritize immediate upgrades to prevent exploitation while implementing additional network security controls to detect and block potentially malicious header sequences.