my biggest concern inst even the malware, is the ban for using it. I dont know how does the apk works. Do you have any idea?
If they scan the APK's that connect to their servers and fail checksum )or whatever method they want to use), this could be a risk. But right now, there does not seem to be any indication this is the case. Of course, this may change at any second.
I would be VERY concerned about Malware if I were you. There is TONS of data on your device and any malware on there not only puts you at risk, but your contacts, accounts and friends/family as well.
Also, there is no way anyone here will post any links to APK's outside official channels because it's akin to pirating (even for free apps/games). There is a reason there are official channels to get apps and linking to outside sources put the users and community as a whole at risk.