Security researchers have discovered at least half a dozen cases in which malicious Android apps slipped through the Google Play safety net to plant malware on Android devices. In a separate case, Android apps promised free shoes but instead delivered a botnet to victims' phones.
In the first instance, researchers at Pradeo found six apps infected with Joker malware. The malware, which exfiltrates data and registers victims for premium subscription services, was found on 11 Android apps in July and has now been detected on an additional six. After notifying Google, Pradeo found that two of the malicious apps were removed from the Google Plau store but four remain active and available to download. According to Pradeo, the six apps it found in August have so far been downloaded more than 200,000 times.
Free high-end athletic shoes are the hook for the other malware campaign, discovered by the Satori Threat Intelligence and Research Team. The campaign, which researchers dubbed "Terracotta," promised (but never delivered) free kicks to victims. Rather than shoes, victims received malware that recruits the device into a botnet that, according to researchers, is "...a customized Android browser packaged alongside a control module written in the React Native development framework."
The software, "...is loaded onto the phone and used to generate fraudulent ad impressions, sold into the programmatic advertising ecosystem, and defrauding advertisers at scale."
While some of the fraudulent apps have been taken out of the Play Store, researchers warn that more appear to replace those removed by Google. The ultimate protection, they say, is that, "As much as we all love a bargain, remember friends don't let friends get scammed online."