CVE-2023-4052 in Firefox
Summary
by MITRE • 08/01/2023
The Firefox updater created a directory writable by non-privileged users. When uninstalling Firefox, any files in that directory would be recursively deleted with the permissions of the uninstalling user account. This could be combined with creation of a junction (a form of symbolic link) to allow arbitrary file deletion controlled by the non-privileged user. *This bug only affects Firefox on Windows. Other operating systems are unaffected.* This vulnerability affects Firefox < 116 and Firefox ESR < 115.1.
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Analysis
by VulDB Data Team • 08/01/2023
The vulnerability identified as CVE-2023-4052 represents a critical privilege escalation and arbitrary file deletion flaw within the Firefox browser's update and uninstallation mechanisms on Microsoft Windows operating systems. This issue stems from improper directory permissions management during the Firefox update process, creating a persistent security weakness that could be exploited by malicious actors to gain elevated privileges and compromise system integrity. The flaw specifically targets the Windows implementation of Firefox and does not affect other operating systems including macOS or Linux, making it a platform-specific vulnerability that requires targeted mitigation strategies. The vulnerability impacts Firefox versions prior to 116 and Firefox ESR versions prior to 115.1, indicating that users running these older versions remain at significant risk of exploitation.
The technical root cause of this vulnerability lies in the Firefox updater's creation of directories with overly permissive access controls that allow non-privileged user accounts to write to these locations. When the uninstallation process begins, the system recursively deletes files within these directories using the permissions of the user account performing the uninstallation. This design flaw creates a path for privilege escalation because a malicious user can manipulate the contents of the writable directory to include junction points or symbolic links that redirect the deletion process to arbitrary locations on the filesystem. The exploitation mechanism leverages the Windows junction functionality to create a malicious link structure that, when processed by the uninstaller, results in the deletion of files outside the intended directory scope. This represents a classic example of insecure temporary file handling and improper privilege management in system-level operations.
The operational impact of this vulnerability extends beyond simple file deletion capabilities to encompass potential system compromise and data loss scenarios. An attacker with low-privilege access could leverage this vulnerability to remove critical system files, browser components, or user data, effectively disrupting normal system operations and potentially creating backdoor access points. The vulnerability's exploitation requires minimal privileges and can be executed through standard user accounts, making it particularly dangerous in enterprise environments where users may have varying levels of access rights. The combination of directory traversal capabilities with arbitrary file deletion creates a powerful attack vector that could be used to disable security software, remove forensic evidence, or compromise system stability. This vulnerability directly aligns with CWE-276, which describes inadequate permissions for created files or directories, and represents a clear violation of the principle of least privilege in system design.
Security mitigations for CVE-2023-4052 primarily focus on immediate version upgrades to Firefox 116 or Firefox ESR 115.1 and later releases where the vulnerability has been patched. Organizations should implement mandatory update policies to ensure all Firefox installations are running patched versions, as the vulnerability can be exploited remotely without user interaction. System administrators should monitor for the presence of affected Firefox versions in their environments and prioritize remediation efforts accordingly. Additional protective measures include implementing application whitelisting policies that restrict execution of untrusted Firefox installations and monitoring for unusual uninstallation activities that might indicate exploitation attempts. The vulnerability also highlights the importance of proper privilege separation in system utilities and the need for careful permission management during update and uninstallation processes. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and persistence mechanisms, specifically covering T1068 for bypassing user access controls and T1566 for social engineering through software supply chain compromise. Organizations should also consider implementing behavioral monitoring to detect unusual file deletion patterns that could indicate exploitation of this vulnerability, particularly in environments where non-privileged users have access to systems where Firefox is installed.