CVE-2016-20088: Comodo Chromodo Unquoted Service Path Privilege Escalation

Technical summary

CVE-2016-20088 is an unquoted service path vulnerability (CWE-428) affecting the ChromodoUpdater service in Comodo Chromodo Browser 52.15.25.664. The service executes with SYSTEM privileges but fails to properly quote its executable path in the Windows registry or service configuration. An attacker with local user-level access can exploit this by crafting a malicious executable and placing it in a location along the service's search path. Upon service initialization—triggered by restart, reboot, or update activity—Windows will execute the attacker's payload with elevated SYSTEM privileges, bypassing standard privilege boundaries.

Business impact

This vulnerability enables privilege escalation from standard user to system-level access on affected machines. For organizations where Comodo Chromodo is deployed, successful exploitation results in complete system compromise: attackers gain the ability to install rootkits, create persistent backdoors, exfiltrate sensitive data, disable security controls, and move laterally across the network. The impact is particularly severe in environments where administrators rely on privilege separation to contain user-initiated threats. Any endpoint running the vulnerable browser version becomes a potential pivot point for adversaries.

Affected systems

Comodo Chromodo Browser version 52.15.25.664 is confirmed vulnerable. Organizations should inventory systems running this browser version, with particular attention to shared workstations, developer machines, and systems where non-privileged users have local access. Verify whether your deployment includes this specific version and whether the ChromodoUpdater service is enabled.

Exploitability

Exploitation requires local access and does not demand sophisticated techniques. An attacker with standard user privileges can drop a specially named executable in a predictable location—often within the Program Files directory or the service working directory—and then wait for or trigger a service restart. No user interaction, network access, or admin credentials are needed beyond the initial local foothold. The attack surface is broad: any mechanism that restarts the system or triggers the update service (including legitimate administrative actions) provides the exploitation window.

Remediation

Update Comodo Chromodo Browser to a patched version that properly quotes the ChromodoUpdater service path. Verify the patch version number against the official Comodo advisory. As an interim control, restrict local user access where possible, disable the ChromodoUpdater service if automatic updates are not required, or use AppLocker/Device Guard policies to prevent unsigned executables from running in service directories. On systems requiring the browser, prioritize patching as the permanent fix.

Patch guidance

Contact Comodo directly or consult their security advisory for the specific patched version that addresses CVE-2016-20088. Apply the patch promptly to all systems running version 52.15.25.664. Test patch deployment in a non-production environment first, as browser updates may affect user workflows or extensions. After patching, verify via Windows Services MMC or Registry that the ChromodoUpdater service path is now properly quoted (path enclosed in double quotes). Restart affected systems to ensure the patched service is active.

Detection guidance

Monitor Windows event logs for ChromodoUpdater service start/stop events and any non-standard child processes spawned by the service. Use Sysmon or EDR tools to log process creation events with parent process as ChromodoUpdater; any suspicious executables should trigger alerts. Check file system activity in %ProgramFiles%\Comodo and related directories for unexpected executable creation or modification. Query the Windows Registry (HKLM\SYSTEM\CurrentControlSet\Services\ChromodoUpdater) to confirm the ImagePath value is quoted. Scan for unquoted service paths using PowerShell or dedicated scanning tools.

Why prioritize this

This is a HIGH-severity vulnerability (CVSS 7.8) enabling local privilege escalation to SYSTEM. While it requires local access, it is trivial to exploit, affects any system running the vulnerable browser, and results in complete machine compromise. The absence of KEV designation does not diminish risk—prioritize based on your deployment footprint. Organizations using Comodo Chromodo should treat this as urgent; those not using it can deprioritize accordingly.

Risk score, explained

The CVSS 3.1 score of 7.8 (HIGH) reflects: local attack vector (reduces overall score but is realistic in multi-user/BYOD environments), low complexity, requirement for low privileges, no user interaction, and high impact across confidentiality, integrity, and availability. The score accurately represents the severity of unauthenticated privilege escalation with immediate and total system compromise. No CVSS modifiers are known to apply; verify threat modeling against your specific environment and control posture.

Frequently asked questions