Windows services and execution-path permissions

Mechanism

A Windows service has an account, command line, start policy, and configurable security descriptor. Writable service configuration or executable inputs can let a lower-privilege principal influence later service execution. Unquoted paths matter only when parsing ambiguity combines with a writable candidate path and a trigger that starts the service.

Practical method

Inspect the service command line, account, and permissions on the executable and parent directories. Determine whether you can change configuration or only file content. Reconstruct candidate executable parsing and check writable locations. Use a harmless marker to verify the service trigger in the lab.

sc.exe qc ChallengeService
Get-Acl C:\Lab\Service | Format-List

Interpreting evidence

A space in a path is not sufficient evidence. Identify the candidate file selected by parsing, its write permissions, and the account used at launch.

Pitfalls and limits

Service control and filesystem permissions are separate. Existing executables may take precedence. A restart right is useful only if the changed input is consumed at restart.