Warez scene groups often compress their binary executables using UPX or similar software.
I've heard somewhere that they do this to obscure the algorithms they use from other groups, but I find this hard to believe as binaries compressed via UPX should be relatively easy to decompress (even if they intentionally mangled parts of the binary so that the compression cannot be reversed using just
upx -d). Is this a valid use-case of UPX and similar software? If not, why would they do this?
Also, antivirus software often flags binaries compressed with UPX falsely as infected files. What is the reason for this?