More than 200 Android apps masquerading as fitness, photo editing, and puzzle apps have been observed distributing spyware called Facestealer to siphon user credentials and other valuable information.

"Similar to Joker, another piece of mobile malware, Facestealer changes its code frequently, thus spawning many variants," Trend Micro analysts Cifer Fang, Ford Quin, and Zhengyu Dong said in a new report. "Since its discovery, the spyware has continuously beleaguered Google Play."

Facestealer, first documented by Doctor Web in July 2021, refers to a group of fraudulent apps that invade the official app marketplace for Android with the goal of plundering sensitive data such as Facebook login credentials.

Of the 200 apps, 42 are VPN services, followed by a camera (20) and photo editing applications (13). In addition to harvesting credentials, the apps are also designed to collect Facebook cookies and personally identifiable information associated with a victim's account.

Additionally, Trend Micro disclosed that it uncovered over 40 rogue cryptocurrency miner apps that target users interested in virtual coins with malware designed to trick users into watching ads and paying for subscription services.

Some of the fake crypto apps, such as Cryptomining Farm Your own Coin, take it one step further by also attempting to steal private keys and mnemonic phrases (or seed phrases) that are used to recover access to a cryptocurrency wallet.

To avoid falling victim to such scam apps, it's recommended that users check negative reviews, verify the legitimacy of the developers, and avoid downloading apps from third-party app stores.

New study analyzes malicious Android apps installed in the wild

The findings come as researchers from NortonLifeLock and Boston University published what they called the "largest on-device study" of potentially harmful apps (PHAs) on Android-based on 8.8 million PHAs installed on over 11.7 million devices between 2019 and 2020.

"PHAs persist on Google Play for 77 days on average and 34 days on third-party marketplaces," the study noted, pointing out the delay between when PHAs are identified and when they are removed, adding 3,553 apps exhibit inter-market migration after being taken down.

On top of that, the research also shows that PHAs linger for a much longer period on average when users switch devices and automatically install the apps when restoring from a backup.

As many as 14,000 PHAs are said to have been transferred to 35,500 new Samsung devices by using the Samsung Smart Switch mobile app, with the apps lasting on the phones for a period of approximately 93 days.

"The Android security model severely limits what mobile security products can do when detecting a malicious app, allowing PHAs to persist for many days on victim devices," the academics said. "The current warning system employed by mobile security programs is not effective in convincing users to promptly uninstall PHAs."