CVE-2015-0802 in Firefox
Summary
by MITRE
Mozilla Firefox before 37.0 relies on docshell type information instead of page principal information for Window.webidl access control, which might allow remote attackers to execute arbitrary JavaScript code with chrome privileges via certain content navigation that leverages the reachability of a privileged window with an unintended persistence of access to restricted internal methods.
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Analysis
by VulDB Data Team • 12/26/2024
The vulnerability identified as CVE-2015-0802 represents a critical access control flaw in Mozilla Firefox versions prior to 37.0, specifically within the browser's implementation of Window.webidl access control mechanisms. This weakness stems from the browser's reliance on docshell type information rather than proper page principal information when determining access privileges for web content. The flaw creates a scenario where malicious actors can exploit the browser's navigation handling to gain unauthorized access to privileged window objects that should remain restricted to chrome-level code execution.
The technical implementation of this vulnerability occurs through content navigation sequences that manipulate the browser's internal state management. When Firefox processes certain types of content navigation, it fails to properly validate the principal context of the navigating content against the target privileged window's access control boundaries. This misconfiguration allows attackers to craft navigation sequences that maintain reachability to privileged windows while simultaneously establishing unintended persistence of access to restricted internal methods. The vulnerability specifically targets the Window.webidl interface which serves as a critical boundary for chrome privilege escalation in the browser's security model.
From an operational perspective, this vulnerability enables remote code execution with chrome privileges, representing a severe escalation from typical web content execution to system-level access control bypass. Attackers can leverage this flaw to execute arbitrary JavaScript code within the privileged chrome context, potentially gaining access to sensitive browser functionality, user data, and system resources that should remain isolated from regular web content. The persistence aspect of this vulnerability means that once exploited, the attacker can maintain elevated privileges across multiple navigation operations, making the attack surface significantly broader than a single execution attempt.
The vulnerability maps directly to CWE-284, which addresses inadequate access control mechanisms, and aligns with ATT&CK technique T1059.007 for JavaScript execution and T1068 for privilege escalation. The flaw demonstrates a fundamental breakdown in Firefox's security model where the browser's navigation handling does not properly enforce the security boundaries between privileged chrome code and untrusted web content. This represents a failure in the browser's security architecture to maintain proper isolation between different privilege levels during content transitions, creating a pathway for malicious actors to bridge the gap between web-level execution and chrome-level privileges.
Mitigation strategies for this vulnerability require immediate patching of Firefox installations to version 37.0 or later where the access control implementation has been corrected. Organizations should also implement network-level monitoring to detect suspicious navigation patterns that might indicate exploitation attempts, particularly around cross-origin navigations that attempt to maintain reachability to privileged windows. Browser hardening measures including disabling unnecessary navigation features and implementing strict content security policies can help reduce the attack surface, though the primary defense remains the application of the official security patch that corrects the docshell type information handling to properly utilize page principal information for access control decisions.