Compress and decompress EXE’s with Free UPX

UPX is a popular open source tool which can pack Windows EXE and other executable formats to reduce their size. The process typically compresses files more than zipping, but otherwise has no apparent effect on the file. Run a packed EXE and it quickly decompresses and launches the original image, with no sign that anything unusual has happened. Executable packers are used by many legitimate developers. If you’ve ever wondered why NirSoft’s programs are so small, for instance, that’s partly because many are compressed by UPX. Unfortunately, the technology also has a down side: packing an EXE obfuscates its contents,… [Continue Reading]