Introduction NSSM (Non-Sucking Service Manager) has long been a staple for system administrators and developers on the Windows platform. Versions like 2.24 , released in the mid-2010s, are celebrated for their ability to turn any executable into a Windows service quickly. However, beneath its utilitarian veneer lies a dangerous attack vector: privilege escalation .
net stop <service_name> net start <service_name> The service runs as (by default for manually installed services), executing malware.exe with the highest privileges. Step 5 – Persistence & Lateral Movement The malware can now add a new admin user, dump credentials from LSASS, or implant a backdoor—all while masquerading as a legitimate service. Real-World Attack Scenario Imagine a corporate environment using a legacy monitoring agent installed via NSSM 2.24 on hundreds of Windows Server 2012 R2 machines. A contractor with limited access discovers the NSSM service LegacyMonitor has its binary stored in C:\ProgramData\Monitor\ . The ProgramData folder, by default, grants BUILTIN\Users write access. nssm-2.24 privilege escalation
If you must use NSSM, migrate to version 2.24 . Better yet, use a maintained alternative like WinSW with XML configuration files that support integrity checks. Conclusion NSSM 2.24 privilege escalation is not a classic buffer overflow or race condition—it is a design weakness amplified by common misconfigurations. Attackers love it because it turns a low-privilege foothold into full SYSTEM access with minimal noise. A contractor with limited access discovers the NSSM
nssm set <service_name> Application "C:\temp\malware.exe" The attacker stops and restarts the service (if they have SERVICE_START and SERVICE_STOP rights) or waits for a system reboot: nssm set <
sc qc <service_name> If the BINARY_PATH_NAME points to an NSSM executable (e.g., C:\nssm-2.24\win32\nssm.exe ), the service is a candidate. Using accesschk.exe from Sysinternals or PowerShell, the attacker checks if they have SERVICE_CHANGE_CONFIG or WRITE_DAC rights:
sc query state= all | findstr "SERVICE_NAME" They then check for NSSM-managed services by looking for display names or descriptions containing "NSSM" or by inspecting the binary path: