A: Use QGIS with the SLYR plugin (commercial but has free trial) or open it in a current ArcGIS Desktop trial (21 days free). ArcGIS Pro can also import older MXDs.
This is the most immediate danger to the user. Websites hosting cracked software are often riddled with malware. The "cracks" or "keygens" used to bypass the software licensing are prime vectors for viruses, ransomware, and trojans. Arcgis 9.3 Free Download Full Version
If you specifically need ArcGIS 9.3 (not a newer version), here are legitimate options: A: Use QGIS with the SLYR plugin (commercial