CVE-2014-1485 in Firefox
Summary
by MITRE
The Content Security Policy (CSP) implementation in Mozilla Firefox before 27.0 and SeaMonkey before 2.24 operates on XSLT stylesheets according to style-src directives instead of script-src directives, which might allow remote attackers to execute arbitrary XSLT code by leveraging insufficient style-src restrictions.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 06/09/2021
The vulnerability described in CVE-2014-1485 represents a critical flaw in the Content Security Policy implementation within Mozilla Firefox and SeaMonkey browsers. This weakness stems from an incorrect interpretation of security directives when processing XSLT (Extensible Stylesheet Language Transformations) content, creating a significant bypass opportunity for malicious actors. The issue specifically affects versions prior to Firefox 27.0 and SeaMonkey 2.24, where the browser's security model fails to properly distinguish between script execution and stylesheet processing, leading to potential code execution vulnerabilities.
The technical flaw manifests in how the Content Security Policy enforces restrictions on XSLT processing. When browsers encounter XSLT stylesheets, they should apply script-src directives to control executable code execution, but the affected versions incorrectly apply style-src restrictions instead. This misclassification allows attackers to craft malicious XSLT documents that bypass intended security boundaries, effectively enabling remote code execution through carefully constructed stylesheet content. The vulnerability operates under CWE-253, which addresses the use of insecure or unverified security controls, and represents a classic case of inadequate input validation and security policy enforcement.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it enables attackers to execute arbitrary XSLT code on victim machines. This capability allows for sophisticated attacks including data exfiltration, system compromise, and further exploitation of the victim's browser environment. Attackers can leverage this weakness to bypass traditional security controls, as the CSP mechanism that should prevent such execution is misconfigured to treat XSLT processing as a stylesheet operation rather than a script execution scenario. The vulnerability directly relates to ATT&CK technique T1059.007 for XSLT Scripting and T1068 for Exploitation for Privilege Escalation, as it enables attackers to execute code with browser privileges.
Organizations and users must implement immediate mitigations to address this vulnerability, including upgrading to Firefox 27.0 or later and SeaMonkey 2.24 or later versions where the CSP implementation has been corrected. Security administrators should also review existing CSP policies to ensure they properly account for XSLT processing restrictions, particularly when implementing content security measures for web applications that may process external stylesheet content. Additional protective measures include disabling XSLT processing in browser configurations where such functionality is not required, implementing network-based intrusion detection systems to monitor for suspicious XSLT content, and conducting security assessments to identify potentially vulnerable web applications that may expose users to this attack vector. The vulnerability underscores the importance of proper security policy enforcement and the need for thorough testing of security controls in complex browser environments where multiple content types interact with security mechanisms.