CVE-2017-7768 in Firefox
Summary
by MITRE
The Mozilla Maintenance Service can be invoked by an unprivileged user to read 32 bytes of any arbitrary file on the local system by convincing the service that it is reading a status file provided by the Mozilla Windows Updater. The Mozilla Maintenance Service executes with privileged access, bypassing system protections against unprivileged users. Note: This attack requires local system access and only affects Windows. Other operating systems are not affected. This vulnerability affects Firefox ESR < 52.2 and Firefox < 54.
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Analysis
by VulDB Data Team • 11/26/2025
The vulnerability identified as CVE-2017-7768 represents a critical privilege escalation flaw within the Mozilla Maintenance Service on Windows operating systems. This security weakness stems from improper access controls and inadequate input validation within the service architecture, allowing unprivileged users to manipulate the service into performing unauthorized file operations. The vulnerability specifically targets the Windows implementation of Firefox's maintenance mechanisms, where the service operates with elevated privileges while failing to properly validate file access requests from untrusted sources.
The technical exploitation of this vulnerability occurs through a carefully crafted manipulation of the Mozilla Windows Updater's status file handling process. An attacker with local system access can convince the Maintenance Service to read arbitrary files by constructing malicious status file requests that the service interprets as legitimate. This flaw operates at the intersection of improper input validation and privilege escalation, where the service's assumption that status file requests originate from trusted sources creates an attack vector. The service's execution context with elevated privileges enables it to bypass standard operating system access controls, reading 32 bytes of any file within the local system's file structure. This represents a classic case of privilege escalation through service manipulation, where the legitimate service becomes a vehicle for unauthorized data access.
The operational impact of this vulnerability extends beyond simple information disclosure, as it fundamentally undermines the security model of the Windows Firefox installation process. An attacker with local access can potentially extract sensitive information from system files, configuration data, or other protected resources that would normally be inaccessible to unprivileged users. The vulnerability affects specific versions of Firefox ESR and standard releases, making it particularly concerning for organizations maintaining legacy browser installations. The attack requires only local system access, meaning that users with basic account privileges can exploit this flaw, making it a significant concern for enterprise security environments where user accounts may not be properly restricted.
Mitigation strategies for this vulnerability focus on both immediate remediation and long-term architectural improvements. Organizations should immediately upgrade to Firefox versions 52.2 ESR or 54.0 and later, which contain patches addressing the privilege escalation mechanism. System administrators should also implement additional controls such as restricting local user access where possible and monitoring for unusual service behavior. The vulnerability aligns with CWE-276, which addresses improper privilege management, and maps to ATT&CK technique T1068, privilege escalation through service manipulation. Security teams should consider implementing application whitelisting policies to prevent unauthorized execution of the Maintenance Service and establish monitoring protocols to detect anomalous file access patterns that might indicate exploitation attempts.
This vulnerability demonstrates the critical importance of proper privilege management in Windows service implementations and highlights how seemingly benign service functionality can become a security risk when access controls are insufficient. The attack vector showcases the need for defense-in-depth strategies where even services with elevated privileges must maintain strict input validation and access control mechanisms. Organizations should conduct regular security assessments of their browser maintenance services and implement continuous monitoring to detect similar privilege escalation vulnerabilities in other software components. The remediation process should include not only software updates but also comprehensive security reviews of service architectures to prevent similar issues from emerging in other applications that may be susceptible to similar manipulation techniques.