Several academic and industry papers detail the dangers of downloading modified "portable" or cracked software: Malware and Cybersecurity : Research from the National University of Singapore
Searching for "AutoCAD 2014 Portable" typically leads to unofficial, modified software versions that carry significant security and legal risks rather than a legitimate product Wiley Online Library Research and White Papers on Pirated Software Risks Download Autocad 2014 Portable 64 Bit
like FreeCAD or LibreCAD that don't require an installation? Several academic and industry papers detail the dangers