A massive fraud campaign utilizing 151 Android apps with 10.5 million downloads was used to subscribe users to premium subscription services without their knowledge. Researchers at Avast discovered the campaign, naming it ‘UltimaSMS,’ and reported 80 associated apps that they found on the Google Play Store. While Google quickly removed the apps, the fraudsters likely amassed millions of dollars in fraudulent subscription charges. The threat actors conducted the UltimaSMS campaign through 151 Android apps that pretended to be discount apps, games, custom keyboards, QR code scanners, video and photo editors, spam call blockers, camera filters, and more. When launching one of these apps for the first time, the app would prompt the user to enter their mobile phone number and email address to access the program’s features. Having the phone number and the required permissions, the app then subscribes the victim to a $40 per month SMS service from which the scammers get a cut as an affiliate partner. Avast’s analysis reveals that the authors of these apps have implemented a system that charges the victim the maximum possible amount based on their location.
Although most of these apps don’t offer the advertised functionality, and despite the numerous bad reviews they had on the Play Store, their creators are still finding success through the sheer volume of submissions. By using so many apps for the UltimaSMS campaign, the scammers maintained a constant influx of victims and preserved their presence on the Play Store despite the constant reporting and take-down action by Google. According to Sensor Tower, the most affected countries are Egypt, Saudi Arabia, Pakistan, and the UAE, all counting over a million victimized users. In the U.S., the number of infected devices is 170,000.
While uninstalling the app will prevent new subscriptions from being made, it will not prevent the existing subscription from being charged again. To avoid future charges, victims need to contact their carrier and ask for a cancellation of all SMS subscriptions. The link to GitHub below contains a complete list of the apps that should be uninstalled immediately. To avoid falling victim to scams of this kind, carriers can disable the premium SMS option if requested. In addition, users should avoid entering their phone number on apps that would not need this information. It is also strongly advised to read reviews before installing an app, and if there is repeated negative feedback, avoid the app altogether.