PUP.Optional.Wajam and all associated detection names refer to a type of Potentially Unwanted Program (PUP) that is a browser add-on marketed as a “social search.” It injects additional adverts into the websites you visit, making it possible to redirect traffic to potentially malicious websites, as well as collect personal information.
For more information on how this happens, as well as evidence of the Wajam add-on being involved in malvertising attacks, please check out this blog on Labs.
Common infection method
PUP.Optional.Wajam is often found detecting one or more parts of another PUP. As it is not related to any specific PUP threat, general PUP avoidance tactics should prevent you from further infection.
Malwarebytes Anti-Malware completely removes this threat. No further clean up is required.
However, it is important to note that after quarantine of this threat, your browser may need to be closed and reopened.