SHA:
- 03108c3c726250d6f3cb11489374632e29cf021a
- 4036ce5bcb2d40da984f09e188af037b2c174ada (modification able to get root access)
An Android Trojan distributed in originally harmless games and applications modified by cybercriminals. The program serves the purpose of installing and removing applications without user knowledge.
Once installed on a mobile device, Android.Backdoor.176.origin starts monitoring the following events:
- BOOT_COMPLETED—OS is booted.
- USER_PRESENT—screen is unlocked.
- CONNECTIVITY_CHANGE—change in network connection.
After such an event is registered, the Trojan is activated.
When launched for the first time, the malicious application sends the following information about the infected device to the command and control server via a POST request:
- IMEI
- IMSI
- Information about the state of internal and external memory
- GPS coordinates
- Screen resolution
- Model name
Moreover, some other information is sent. The Trojan exchanges data with the server in JSON format (JavaScript Object Notation).
After that, Android.Backdoor.176.origin extracts a malicious module from its body and launches it. The module connects to the Trojan using Binder. This component is responsible for performing all malicious activities. In particular, it can download and install various programs and monitor incoming and outgoing calls and messages.
Some modifications of Android.Backdoor.176.origin can get root privileges on infected devices. For that, they download from the Internet a modified version of Root Master and launch it. Then these Trojans copy two executable ELF files—the .rt_bridge file (Android.Rootkit.1) and the .rt_daemon file (Android.Rootkit.2)—to the /system/xbin folder. These two files have the same features as the SU utility. Once launched, .rt_bridge checks that it is run by an allowed process and, if so, starts a root terminal.
Then Android.Backdoor.176.origin downloads the chattr utility from the Internet and, using this utility, sets the “immutable” attribute for its own APK file via the terminal. As a result, even if the user uninstalls the Trojan, once the system is rebooted, the malicious program will be reinstalled, and the mobile device will stay infected.