CVE-2016-20090 in Dragon Browser
Summary
by MITRE • 06/19/2026
Comodo Dragon Browser versions up to 52.15.25.663 contain a privilege escalation vulnerability in the DragonUpdater service due to an unquoted service path running with SYSTEM privileges. A local attacker can insert a malicious executable in the service path and execute arbitrary code with elevated privileges upon service restart or system reboot.
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Analysis
by VulDB Data Team • 06/19/2026
The Comodo Dragon Browser vulnerability represents a critical privilege escalation flaw within the DragonUpdater service component that operates with SYSTEM level privileges. This vulnerability stems from an improperly configured service path that lacks proper quotation marks around the executable file location, creating a directory traversal opportunity that malicious actors can exploit. The service executes with elevated privileges, making it an attractive target for attackers seeking to elevate their local system access to the highest administrative level. According to the Common Weakness Enumeration framework, this vulnerability maps to CWE-428 which specifically addresses unquoted service paths as a means of privilege escalation. The ATT&CK framework categorizes this as a privilege escalation technique under T1068, where adversaries leverage service misconfigurations to gain elevated system access. The vulnerability exists because the service path contains spaces in the directory structure without proper quotation, allowing an attacker to place a malicious executable in a parent directory that will be executed when the service restarts.
The technical exploitation of this vulnerability requires a local attacker to place a malicious executable in a specific location within the service path directory structure. When the DragonUpdater service restarts either automatically or following a system reboot, the service will execute the malicious binary from the unquoted path instead of the legitimate executable. This occurs because Windows resolves the path from left to right, and the unquoted path allows for directory traversal where the system will execute the first matching executable in the path hierarchy. The attacker can leverage this by creating a malicious executable with the same name as the legitimate service executable but placing it in a directory that appears earlier in the Windows search path. The service will execute this malicious binary with SYSTEM privileges, enabling the attacker to perform actions such as installing additional malware, modifying system files, or creating persistence mechanisms. The vulnerability is particularly dangerous because it requires no special privileges to exploit and can be triggered automatically during system maintenance operations.
The operational impact of this privilege escalation vulnerability extends beyond simple code execution to encompass complete system compromise and persistent access. Once an attacker achieves SYSTEM level execution through this vulnerability, they can effectively bypass all user-level security controls and access sensitive system resources. The attacker gains the ability to modify or delete critical system files, install rootkits, access encrypted data, and establish backdoor access that persists across system reboots. This vulnerability also enables attackers to perform lateral movement within a network by extracting credentials from the compromised system or using the elevated privileges to access other network resources. The impact is particularly severe in enterprise environments where multiple users may have local access to systems running affected browser versions, potentially allowing a single compromised machine to serve as a foothold for broader network infiltration. The vulnerability's automatic triggering during service restarts or system reboots makes it especially dangerous as it can be exploited without requiring user interaction or specific timing.
Mitigation strategies for this vulnerability should focus on immediate service path remediation and broader system hardening measures. The primary fix involves properly quoting the service path to prevent directory traversal attacks, which can be achieved by modifying the service configuration to include quotation marks around the executable path. System administrators should also implement the principle of least privilege by ensuring that services run with minimal required privileges rather than SYSTEM level access where possible. Additional protective measures include regular security audits of service configurations, implementing application whitelisting policies, and monitoring for suspicious service execution patterns. The vulnerability highlights the importance of proper service configuration management and should be addressed as part of regular security maintenance procedures. Organizations should also consider implementing endpoint detection and response solutions that can monitor for unusual service execution patterns or unauthorized modifications to service paths. Regular patch management processes should be enhanced to ensure that browser updates are applied promptly, as this vulnerability was addressed in later versions of the Comodo Dragon Browser. The remediation process should include comprehensive testing to ensure that the service path modification does not negatively impact legitimate service functionality while maintaining the security hardening measures.