Restore it from quarantine immediately. Then upload the file to VirusTotal to verify. If confirmed clean, add an exclusion rule for your CATIA installation folder.
Many users wonder: "Is just one DLL really that important?" The answer is , particularly in a 64-bit environment. Here is why: catia v5r20 sp0 js0group.dll 64bit
Only if the source computer has the exact same version: CATIA V5R20, SP0, 64-bit, same build number. Even then, you should re-register it. Safer to repair the installation. Restore it from quarantine immediately
If JS0GROUP.dll is missing, corrupted, or the wrong bit-version, CATIA will fail to launch entirely, often presenting a generic "Application failed to start" error or crashing immediately upon startup. same build number. Even then