Check Point researchers have unearthed multiple malicious Android apps on the Google Play Store posing as an antivirus applications to deploy the SharkBot Android trojan.
The malicious banking trojan was initially spotted in November last year when it was only being deployed via third-party application stores. The primary motive was on initiating illegal money transfers via Automatic Transfer Systems (ATS) by auto-filling fields in authentic applications.
Last month, NCC Group reported that multiple SharkBot droppers had infiltrated Google Play, all of which showed similar code and behavior. The first SharkBot dropper discovered in Google Play masqueraded as antivirus solutions. It was identified as a downgraded version of the trojan containing only minimum features, but capable of fetching and installing the full version at a later date.
Apparently, on March 9th, Google removed four apps in question, and a few days after that, another SharkBot dropper was identified. The app was reported right away, so no installations for this one. The same happened on March 22 and 27. Those new droppers got removed from Google Play due to quick discovery.
According to Check Point researchers, they identified a total of seven droppers in Google Play, published from developer accounts that were active in late 2021, and which had some of their applications removed from the store. However, these malicious apps have been already installed more than 15,000 times before the takedown from the store.
Once installed on an Android device, SharkBot exploits Android's Accessibility Services permissions to present fake overlay windows on top of legitimate banking apps. Thus, when victims enter their usernames and passwords in the windows that mimic benign credential input forms, the stolen data is sent to a malicious server.
“What is interesting and different from the other families is that SharkBot likely uses ATS to also bypass multi-factor authentication mechanisms, including behavioral detection like bio-metrics, while at the same time it also includes more classic features to steal user’s credentials,” NCC Group stated.
The malicious Android trojan also employs geofencing features and bypassing techniques, which makes it unique from other mobile banking viruses. The particular features include ignoring the users from China. Romania, Russia, Ukraine, Belarus, India. The majority of victims reside in Italy and the United Kingdom.
