What was the file name and location of this detection ?
By default avast doesn’t scan for PUPs
Potentially Unwanted Program - See http://searchsecurity.techtarget.com/sDefinition/0,,sid14_gci1066761,00.html. Not included in this definition are tools which can be used for good or evil, some have been legitimately installed for a specifically good purpose, but could have been unknowing installed for a malicious purpose.
Not all antivirus programs scan for PUPs and avast has it turned off by default (an exception being the boot-time scan).
You can change the avast scan settings to scan for PUPs, but that in its own right brings other issues. The user has to be aware of what a PUP classification is, what is installed on your system and what it does, then the hardest part determine why this would be considered a PUP and what action to take.