Update: Since April 24, when the article below was first published, Check Point researchers learned that the FalseGuide attack is far more extensive than originally understood. Five additional apps containing the malware were found on Google Play, developed by “Анатолий Хмеленко.” The apps were uploaded to the app store as early as November 2016, meaning they hid successfully for five months, accumulating an astounding number of downloads. The updated estimate now includes nearly 2 million infected users

***

Is someone trying to build a botnet on Google Play?

Check Point mobile threat researchers detected a new strain of malware on Google Play, Google’s official app store. The malware, dubbed “FalseGuide,” was hidden in more than 40 guide apps for games, the oldest of which was uploaded to Google Play on February 14, 2017. Several of the apps managed to reach more than 50,000 installs, and the total number of infected devices is estimated to reach up to 600,000 devices. Check Point notified Google about the malware, and it was swiftly removed from the app store. At the beginning of April, two new malicious apps were uploaded to Google Play containing this malware, and Check Point notified Google once again.

Similar to previous malware found on Google Play, such as Viking Horde and DressCode,

FalseGuide creates a silent botnet out of the infected devices for adware purposes. A botnet is a group of devices controlled by hackers without the knowledge of their owners. The bots are used for various reasons based on the distributed computing capabilities of all the devices.

FalseGuide requests an unusual permission on installation – device admin permission. The malware uses the admin permission to avoid being deleted by the user, an action which normally suggests a malicious intention. The malware then registers itself to a Firebase Cloud Messaging topic which has the same name as the app. Once subscribed to the topic, FalseGuide can receive messages containing links to additional modules and download them to the infected device. After a long wait, we were able to receive such a module and determine that the botnet is used to display illegitimate pop-up ads out of context, using a background service that starts running once the device is booted. Depending on the attackers’ objectives, these modules can contain highly malicious code intended to root the device, conduct a DDoS attack, or even penetrate private networks.

FalseGuide masquerades as guiding apps for games for two major reasons. First, guiding apps are very popular, monetizing on the success of the original gaming apps. Second, guiding apps require very little development and feature implementation. For malware developers this is a good way to reach a widespread audience with minimal effort. The malicious apps were submitted under the names of two fake developers – Sergei Vernik and Nikolai Zalupkin, suggesting a Russian connection, while the second is clearly (to a Russian speaker) a made up name.

Mobile botnets are a growing trend since early last year, growing in both sophistication and reach. This type of malware manages to infiltrate Google Play due to the non-malicious nature of the first component, which only downloads the actual harmful code. Users shouldn’t rely on the app stores for their protection, and implement additional security measures on their mobile device, just as they use similar solutions on their PCs.

Appendix 1 – list of malicious apps found on Google Play

Package name App name Date Min Max free.oosapp.infofifamobile Guide or FIFA Mobile 21.2.17 50000 100000 info.artapp.guidelegonexoknights Guide for LEGO Nexo Knights 15.2.17 10000 50000 free.oosapp.inforollingsky Guide for Rolling sky 20.2.17 5000 10000 info.artapp.guidelegocitymycity Guide for LEGO City My City 14.2.17 10000 50000 free.oosapp.infoterraria Guide for Terraria 20.2.17 10000 50000 free.oosapp.infoworldoftanksblitz Справочник для World of Tanks 20.2.17 info.artapp.guidezombietsunami Руководство для Zombie Tsunami 15.2.17 info.artapp.guidedriftzone Руководство для Drift Zone 2 22.2.17 1 5 info.artapp.guidemobilelegendsbangbang Руководство для Mobile Legends 22.2.17 1 5 info.artapp.guideinjusticegodsamongus Руководство для Injustice Gods 22.2.17 1 5 info.artapp.guideninjagoshadowofronin Руководство для Injustice Gods 22.2.17 1 5 info.artapp.guideasphaltairborne Руководство для Asphalt 8 22.2.17 1 5 free.oosapp.infocriminalcase Справочник для Criminal Case 21.2.17 1 5 free.oosapp.infonbalivemobile Справочник для NBA LIVE Mobile 21.2.17 1 5 free.oosapp.infohayday Справочник для NBA LIVE Mobile 21.2.17 1 5 free.oosapp.infosubwaysurfers Справочник для Subway Surfers 21.2.17 1 5 free.oosapp.infozombietsunami Справочник для Zombie Tsunami 21.2.17 1 5 free.oosapp.infogtasanandreas Справочник для Zombie Tsunami 20.2.17 1 5 info.artapp.guideterraria Руководство для Terraria 18.2.17 1 5 info.artapp.guidehayday Руководство для Hay Day 18.2.17 5 10 info.artapp.guideworldoftanksblitz Руководство для World of Tanks 18.2.17 1 5 mobi.guide.pokemon.go.pro Guide for Pokemon GO 1.3.17 50000 100000 guide.tipsamazingspiderman.infopro Guide Amazing Spider-Man 2 2.3.17 1000 5000 mobi.proguide.lego.marvel.superhero ProGuide LEGO Marvel Superhero 1.3.17 1000 5000 guide.tipsdreamleaguesoccer.infopro Guide Dream League Soccer 2.3.17 10000 50000 mobi.leguide.lego.city.under.cover.pro LEGUIDE LEGO City Undercover 27.2.17 10000 50000 mobi.guide.fnaf2.pro Руководство для FNAF 2 1.3.17 1 5 mobi.guide.roblox.pro Руководство для Roblox 1.3.17 1 5 guide.tipsfnaftwo.infopro Guide For FNAF 2 8.3.17 1000 5000 guide.tipsgreattheautovipcity.infopro Инструцкция The Auto Vip City 3.3.17 1 5 mobi.tips.superr.mario.pro Руководство для Super Mario 28.2.17 mobi.great.the.auto4.pro Руководство Great The Auto 4 28.2.17 mobi.guide.cadillacs.pro Руководство для Cadillacs 1.3.17 mobi.guide.amazing.spider.man2.pro Руководство для Spider-Man 2 28.2.17 guide.tipssupermario.infopro Инструкция к Super Mario 2.3.17 guide.tipslegofriends.infopro Интсрукция к LEGO Friends 3.3.17 1 5 guide.tipsgreattheautofive.infopro Инструкция к Great The Auto 5 2.3.17 1 5 guide.tipsgreattheautofour.infopro Инструкция к Great The Auto 4 8.3.17 1 5 guide.tipscadillacs.infopro Guide for Cadillacs 3.3.17 5000 10000 guide.tipsroblox.infopro Guide for Roblox 3.3.17 10 50 mobi.guide.dream.league.soccer.pro Руководство для League Soccer 28.2.17 1 5 mobi.leguide.lego.city.mycity.pro LEGUIDE LEGO City My City 27.2.17 5000 10000 com.megaguide.rollingsky.tricks Guide for Rolling Sky 11.4.17 500 1000 com.megaguide.legoninjagotournament.tricks Guide for Ninjago Tournament 6.4.17 50000 100000 free.guidegame.hungrysharkfree Guide for Hungry Shark World 22.11.16 100000 500000 free.guidegame.fifafree Guide For FIFA 17 30.11.16 10000 50000 free.guidegame.slitherfree Guide for slither.io 29.11.16 50000 100000 free.guidegame.mortalkombatxfree Guide for Mortal Kombat X 23.11.16 50000 100000 free.guidegame.shadowfightfree Guide for Shadow fight 3 and 2 23.11.16 100000 500000 Total 528535 1846160

Appendix 2 – list of SHA256 hashes:

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8a9133039c1826c78a0b87142e8daa391179424d42705fc55d23d4ccbc01c816

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