CVE-2011-3648 in Firefox
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in Mozilla Firefox before 3.6.24 and 4.x through 7.0 and Thunderbird before 3.1.6 and 5.0 through 7.0 allows remote attackers to inject arbitrary web script or HTML via crafted text with Shift JIS encoding.
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Analysis
by VulDB Data Team • 11/26/2021
The vulnerability identified as CVE-2011-3648 represents a critical cross-site scripting flaw affecting Mozilla Firefox and Thunderbird email clients. This vulnerability stems from improper handling of Shift JIS encoded text within the browser's rendering engine, creating a pathway for remote attackers to execute malicious code through crafted text inputs. The flaw specifically impacts Firefox versions prior to 3.6.24 and 4.x through 7.0, alongside Thunderbird versions before 3.1.6 and 5.0 through 7.0, making it a widespread concern across multiple product lines and versions. The vulnerability operates by exploiting the browser's text encoding mechanisms, where Shift JIS encoded content is processed without adequate sanitization, allowing attackers to inject arbitrary web scripts or HTML code that executes in the context of the victim's browser session.
Technical exploitation of this vulnerability relies on the browser's failure to properly validate and sanitize text inputs that utilize Shift JIS encoding standards. When Firefox or Thunderbird processes text containing Shift JIS encoded characters, the parsing mechanism does not adequately distinguish between legitimate encoded content and malicious script payloads. This encoding-based injection vector operates under CWE-79 which specifically addresses cross-site scripting vulnerabilities through improper input handling. The flaw demonstrates a classic case of insufficient output escaping where the application fails to neutralize user-supplied data before rendering it in the browser context. Attackers can craft malicious content using Shift JIS encoding that bypasses normal security filters, allowing script execution when the content is displayed to users. The vulnerability's impact extends beyond simple script injection as it can be leveraged for session hijacking, credential theft, and other malicious activities that compromise user security.
The operational impact of this vulnerability creates significant risk for organizations and individual users who rely on affected browser versions. Users may encounter malicious content through various attack vectors including email messages, web forms, or compromised websites, with the Shift JIS encoding providing a stealthy method to bypass traditional security controls. The vulnerability enables attackers to execute arbitrary code within the user's browser context, potentially leading to full system compromise through additional attack chains. This weakness aligns with ATT&CK technique T1566 which covers social engineering tactics, particularly through spearphishing with a malicious attachment or link. The vulnerability also relates to T1059 which covers command and scripting interpreter techniques, as the injected scripts can execute various malicious commands. Organizations using affected versions face potential data breaches, unauthorized access to sensitive information, and compromised user sessions, making this vulnerability particularly dangerous in enterprise environments where user trust and security are paramount.
Mitigation strategies for CVE-2011-3648 primarily focus on immediate software updates and version management. Users and organizations should prioritize upgrading to patched versions of Firefox and Thunderbird, specifically Firefox 3.6.24 and later, Firefox 4.0 through 7.0, and Thunderbird 3.1.6 and later. The implementation of proper input validation and output encoding mechanisms should be enforced across all applications handling user-supplied text data. Network security controls including web application firewalls and content filtering systems can provide additional layers of protection by detecting and blocking suspicious Shift JIS encoded content. Security awareness training for end users remains crucial in preventing successful exploitation through phishing attacks that leverage this vulnerability. Regular security assessments and vulnerability scanning should identify systems running unpatched versions, while proper monitoring of network traffic can help detect potential exploitation attempts. Organizations should also implement strict content security policies and ensure that all user-generated content undergoes thorough sanitization before being rendered in browser contexts. The vulnerability highlights the importance of comprehensive security testing across different text encoding standards and the necessity of maintaining up-to-date security patches to prevent exploitation of known vulnerabilities.