Pierluigi Paganini July 19, 2022

Google blocked dozens of malicious apps from the official Play Store that were spreading Joker, Facestealer, and Coper malware families.

Google has removed dozens of malicious apps from the official Play Store that were distributing Joker, Facestealer, and Coper malware families.

Researchers from security firms Pradeo discovered multiple apps spreading the Joker Android malware.

The Joker malware is a malicious code camouflaged as a system app and allows attackers to perform a broad range of malicious operations, including disabling the Google Play Protect service, installing malicious apps, generating fake reviews, and showing ads.

The spyware is able to steal SMS messages, contact lists, and device information and to sign victims up for premium service subscriptions.

Researchers from Pradeo discovered 4 new malicious apps on Google Play that were infected with the Joker malware and acting as droppers. The apps have been installed by 100.000+ users, according to the security firm.

ThreatLabz researchers announced to have discovered over 50 unique Joker downloader apps on the Play Store till now. These apps were downloaded a total of over 300k times belonging to the following common categories:

• Communication (47.1%)
• Health
• Personalization (5.9%)
• Photography
• Tools (39.2%)

“The tools and communication were among the most targeted categories covering the majority of the Joker-infected apps. ThreatLabz discovered daily uploads of apps containing the Joker malware indicating the high activity level and persistence of the adversary group.” reads the analysis published by Zscaler. “Consistent with previous findings, ThreatLabz latest discoveries belonging to the Joker malware campaign continue to follow similar developer naming patterns and use of familiar techniques.”

ThreatLabz experts also discovered in the Play Store marketplace malicious apps infected with the Facestealer and Coper malware.

The Facestealer spyware was first spotted on July 2021 by Dr. Web researchers, the development team behind the threat has frequently changed its code. The malware was designed to steal Facebook users’ logins and passwords and authentication tokens.

The Coper malware is a banking trojan that targets banking applications in Europe, Australia, and South America. Threat actors distribute the apps by disguising them as legitimate apps in the Google Play Store.

“Once downloaded, this app unleashes the Coper malware infection which is capable of intercepting and sending SMS text messages, making USSD (Unstructured Supplementary Service Data) requests to send messages, keylogging, locking/unlocking the device screen, performing overly attacks, preventing uninstalls and generally allowing attackers to take control and execute commands on infected device via remote connection with a C2 server.” continues the report. “The result of these activities ultimately leads to attackers gaining information and access they can leverage to steal money from victims.”

Facestealer and Coper dropper apps were uploaded to the Play Store as Vanilla Camera (cam.vanilla.snapp) and Unicc QR Scanner (com.qrdscannerratedx).

Below are recommendations published by the experts:

• Don’t install unnecessary, untrusted, and un-vetted apps on your mobile device.
• Look for apps with very high install numbers and positive reviews.  
• Don’t grant notifications listener permissions and escalated accessibility permissions to apps you don’t fully trust.
• Avoid installing messaging apps if possible or use extreme caution and take the time to research and ensure that the app is well known and reviewed.
• If you become a victim of a malicious app from the Play Store, inform Google about it immediately through the support options in your play Store app.

Follow me on Twitter: @securityaffairs and Facebook

Pierluigi Paganini

(SecurityAffairs – hacking, Joker)

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