A quick websearch reveals a Malwarebytes wiki website, that says:
"RiskWare.IFEOHijack is a generic detection for programs that set a debugger for other executables.
When an executable is listed under the IMAGE FILE EXECUTION OPTIONS key and it has a debugger value set, Windows always checks under that key what the valuedata is and launches that "debugger" instead of the executable.
RiskWare.IFEOHijack could be a flag for more serious problems. By setting a debugger for an executable, you basically intercept any calls to that executable and run another executable instead. The debugger is often set for taskmanager.exe.The debugger setting flagged by RiskWare.IFEOHijack can be made by legitimate substitutes for the Windows Task Manager, but it can also be done by malware that doesn't want the user to find a suspicious process in the list shown by the Task Manager."
If you are suspicious about ATLAS OS, the entire development is open source, which means you can read the entire code right now at github.