Pierluigi Paganini August 01, 2018

Google recently removed 145 applications from the official Google Play store because they were found to carry malicious Windows executables inside.

Researchers from Palo Alto Networks revealed that Google removed more than 145 apps from the Play store  because they were carrying a Windows malware,

The apps were uploaded to the Google Play store between October and November 2017, this means that for months Android users were exposed to the attack. In some cases, the apps have been downloaded thousands of times and were rated with 4-stars.

The malicious code included in the code of the app was developed to compromised Windows systems and leverage the Android device as an attack vector.

“Notably, the infected APK files do not pose any threat to Android devices, as these embedded Windows executable binaries can only run on Windows systems: they are inert and ineffective on the Android platform.” reads the analysis published by Palo Alto networks.

“The fact that these APK files are infected indicates that the developers are creating the software on compromised Windows systems that are infected with malware. This type of infection is a threat to the software supply chain, as compromising software developers has proven to be an effective tactic for wide scale attacks.”

Palo Alto Networks reported that the malicious PE files when executed on a Windows system will perform these suspicious activities:

• Creates executable and hidden files in Windows system folders, including copying itself
• Changes Windows registry to auto-start themselves after restarting
• Attempts to sleep for a long period
• Has suspicious network connection activities to IP address 87.98.185.184 via port 8829

Some of the apps included multiple malicious PE files at different locations, with different file names, anyway the experts the experts noticed that malware were found embedded in most applications.

The researchers discovered that one of malware was included in 142 APKs, a second malicious code was found in 21 APKs. 15 apps were found containing both PE files inside.

In one case, the malicious PE file that was included in the APK of most of the Android apps was a keylogger.

“After investigating all those malicious PE files, we found that there is one PE file which infects most of the Android apps, and the malicious activity of that PE file is key logging.” continues the analysis.

“On a Windows system, this key logger attempts to log keystrokes, which can include sensitive information like credit card numbers, social security numbers and passwords.”

The attackers attempted to conceive the PE files by using fake names that look like legitimate, such as Android.exe, my music.exe, COPY_DOKKEP.exe, js.exe, gallery.exe, images.exe, msn.exe and css.exe.

The researchers discovered that not all the apps uploaded by the same developers were infected with the malicious files, likely because they were using different development platform for the apps.

“The malicious PE files cannot directly run on the Android hosts. However, if the APK file is unpacked on a Windows machine and the PE files are accidentally executed, or the developers also issue Windows-based software, or if the developers are infected with malicious files runnable on Android platforms, the situation will go much worse.” concludes Palo Alto Networks.

“The development environment is a critical part of the software development life cycle. We should always try to secure it first. Otherwise other security countermeasures could just be attempts in vain,” 

Pierluigi Paganini

(Security Affairs – Play Store,  malware)

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