DSynchronize Portable is malware? According to Avast

As is occasionally the case, this is a false positive. This can be verified by viewing the scan results for DSynchronize Portable.

Although these results do show currently 12 AV products detecting the file as having a virus, you'll note that most of them indicate "generic" or "heuristic", both of which indicate these are guesses.

Avast in particular is bad for giving false positives a fair bit. Also, a number of the AV providers are using the same back end, hence why the "detections" are identical for some, but different for others.

As a user of Avast, you are able to report the false positive to Avast, whom will correct it upon verifying that it is safe.