CVE-2013-1672 in Firefox
Summary
by MITRE
The Mozilla Maintenance Service in Mozilla Firefox before 21.0, Firefox ESR 17.x before 17.0.6, Thunderbird before 17.0.6, and Thunderbird ESR 17.x before 17.0.6 on Windows allows local users to bypass integrity verification and gain privileges via vectors involving junctions.
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Analysis
by VulDB Data Team • 05/11/2021
The vulnerability identified as CVE-2013-1672 affects the Mozilla Maintenance Service component within several Mozilla applications running on Windows operating systems. This flaw exists in versions of Firefox before 21.0, Firefox ESR 17.x before 17.0.6, Thunderbird before 17.0.6, and Thunderbird ESR 17.x before 17.0.6. The core issue lies in how the maintenance service handles file system operations, specifically when processing junction points or symbolic links in the Windows file system. Junctions represent a Windows file system feature that allows one directory to be redirected to another location, creating a symbolic link that appears as a directory to applications. The vulnerability arises because the Mozilla Maintenance Service fails to properly validate or sanitize these junction points during the update process, creating a path traversal condition that can be exploited by local attackers.
The technical flaw manifests in the maintenance service's improper handling of file paths when verifying update integrity. When the service processes updates, it does not adequately check whether the target files or directories are junction points that could redirect to arbitrary locations on the file system. This allows a local attacker to create malicious junctions that point to sensitive system files or directories, effectively bypassing the intended integrity verification mechanisms. The vulnerability specifically targets the update installation process where the service attempts to replace or modify existing files. Attackers can exploit this by manipulating the file system to redirect update operations to locations where they can execute arbitrary code with elevated privileges, typically those of the SYSTEM user who runs the maintenance service.
The operational impact of this vulnerability is significant as it enables local privilege escalation attacks on affected systems. An attacker with low-privilege user access can leverage this vulnerability to gain SYSTEM-level privileges, which represents the highest level of access on Windows systems. This escalation occurs because the Mozilla Maintenance Service runs with elevated privileges to perform system updates, and the flaw allows an attacker to manipulate the update process to execute malicious code in this privileged context. The vulnerability affects all Windows users running the affected versions of Mozilla applications, making it a widespread concern for organizations and individual users alike. The exploitability is relatively straightforward since it only requires local access and the ability to create file system junctions, which are standard Windows features available to regular users.
Mitigation strategies for this vulnerability include immediate patching of all affected Mozilla applications to versions that contain the necessary security fixes. Organizations should prioritize updating Firefox, Firefox ESR, Thunderbird, and Thunderbird ESR installations to versions 21.0 or later for Firefox and 17.0.6 or later for Thunderbird, as these releases contain the required patches to address the junction handling issue. System administrators should also implement monitoring for suspicious file system activity, particularly around junction point creation and modification near application directories. The vulnerability aligns with CWE-22 Path Traversal and CWE-787 Out-of-bounds Write patterns, as it involves improper path validation and potential privilege escalation. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques, specifically T1068 Local Privilege Escalation and T1547 Registry Run Keys, as the exploitation involves manipulating system update processes to gain elevated access. Organizations should also consider implementing application whitelisting policies to restrict the execution of unauthorized binaries during update processes, further reducing the attack surface for this class of vulnerability.