Recently, Google did some house cleaning. They removed ten different apps from the Play Store, all of which contained droppers for financial Trojans, this according to a recent blog post by Check Point Research.
Apparently, all ten of the poisoned apps were submitted by the same threat actor, who took pains to get them past Google's extensive verification process.
They even went so far as to create separate developer accounts for each of the apps in question.
Of course, that alone wouldn't have been enough to get past Google. So the attacker took the step of creating innocent looking utilities, with functionality copied and pasted from existing, legitimate, open-source Android apps. On top of that, the hackers utilized Firebase as their command-and-control platform and GitHub was exploited to handle payload downloads. Further, the C2 infrastructure contained an "Enable" flag that was set to "false" until Google had taken the step of actually publishing the app on the Play Store.
In other words, this was a highly sophisticated operation that left nothing to chance.
The Check Point researchers who discovered the threat, dubbed Clast82, had this to say about the threat:
"If the infected device prevents installations of applications from unknown sources, Clast82 prompts the user with a fake request, pretending to be 'Google Play Services' requesting the user to allow the installation every five seconds.
The hacker behind Clast82 was able to bypass Google Play's protections using a creative, but concerning, methodology. With a simple manipulation of readily available third-party resources -- like a GitHub account, or a FireBase account -- the hacker was able to leverage readily available resources to bypass Google Play Store's protections."
Although we don't yet know who was behind the attack, the group has obvious skill, and this is almost certainly not the last we've seen of them. Stay vigilant out there.
