CVE-2016-20087 in Fortitude HTTP
Summary
by MITRE • 06/19/2026
Fortitude HTTP 1.0.4.0 contains an unquoted service path vulnerability that allows local users to execute arbitrary code with elevated privileges by exploiting the service binary path. Attackers can insert malicious executables in the system root path that execute with SYSTEM privileges during service startup or system reboot.
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Analysis
by VulDB Data Team • 06/19/2026
The vulnerability in Fortitude HTTP version 1.0.4.0 represents a critical security flaw that stems from improper service installation practices and weak path validation mechanisms. This unquoted service path vulnerability occurs when a Windows service is installed with a path that contains spaces but lacks proper quotation marks around the complete path. The service binary path typically contains a space such as "C:\Program Files\Fortitude\fortitude.exe" but is installed without quotation marks, creating an exploitable condition where the operating system attempts to execute the first portion of the path as a separate executable. This fundamental design flaw aligns with CWE-428, which specifically addresses the improper handling of unquoted service paths in Windows environments. The vulnerability exists because Windows resolves the path from left to right, treating each directory name as a potential executable, thereby creating a privilege escalation vector that can be exploited by local attackers.
The technical exploitation of this vulnerability relies on the attacker's ability to place malicious executables in directories that precede the intended service binary path. When the vulnerable service starts or during system reboot, Windows attempts to execute the first component of the unquoted path, which can be manipulated by an attacker who has local write access to the system. For instance, if the service path is "C:\Program Files\Fortitude\fortitude.exe" and lacks proper quotation, the system will first look for "C:\Program.exe" and execute that if it exists. This creates a dangerous condition where an attacker can place a malicious binary named "Program.exe" in the root directory, effectively hijacking the service execution flow. The vulnerability directly maps to attack techniques described in the MITRE ATT&CK framework under T1035 for service execution and T1068 for local privilege escalation. The exploitation process requires minimal privileges for initial placement but results in SYSTEM-level execution, making it particularly dangerous for attackers seeking persistent access.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with complete control over the compromised system. When the service executes with SYSTEM privileges, the attacker gains unrestricted access to system resources, user data, and network capabilities. This privilege escalation can be leveraged to establish persistent backdoors, exfiltrate sensitive information, or pivot to other systems within the network. The vulnerability is particularly concerning because it can be exploited automatically during system boot processes, ensuring that the malicious code executes without requiring user interaction. Additionally, since the service binary path is typically configured during installation, organizations may not be aware of the vulnerability until after deployment, making it difficult to detect and remediate. The impact is compounded by the fact that this vulnerability can be exploited by any local user with sufficient privileges to modify system directories, potentially allowing attackers who have gained access through other means to escalate their privileges.
Mitigation strategies for this vulnerability must address both the immediate exploitation risk and prevent future installations from creating similar conditions. The primary recommendation is to properly quote service paths during installation, ensuring that paths containing spaces are enclosed in double quotation marks to prevent path resolution issues. System administrators should conduct comprehensive audits of installed services to identify and correct any existing unquoted service paths, particularly those with spaces in their directory names. The implementation of application whitelisting policies and strict file system permissions can further reduce the risk by preventing unauthorized modifications to critical system directories. Organizations should also consider implementing regular security assessments that include service path validation as part of their vulnerability management processes. Microsoft recommends using the sc query command to identify services with unquoted paths and applying proper quoting during service configuration. The vulnerability can be remediated through service reinstallation with properly quoted paths, or by modifying existing service configurations to ensure that all binary paths are correctly quoted. Additionally, network segmentation and principle of least privilege enforcement can limit the potential damage from successful exploitation, while continuous monitoring and alerting systems can detect suspicious service execution patterns that may indicate compromise.