Analysis of Android.Golem downloader component

Recently, we came across a new malware which seems to be a module of a recent Android trojan named dubbed Golem.

Golem has been found in several countries and hundreds of thousands of phones have already been infected, according to reports.

We performed detailed analysis of the malware using JEB, the operations achieved by the malware can be divided into several steps:

Step 1

When user start the phone or unlock the screen or light the screen, the malware will automatically download a file named “conf_plugin.txt” which contains configuration information like “update”, “md5”, “url”, etc.

Step 2

Then the malware will check if there is a jar file named “ic.jar” in phone memory, if not or if its md5 is different from the md5 in “conf_plugin.txt” (which means the local dex is different from the dex in remote server), malware will download the dex.

Step 3

After that, the malware will install and run the dex and execute the “onCreate” function in the “com.facebook.mini.service.RunService” class.

The complete process can be represented by the graph below:

Based on the analysis, the malware can automatically download, launch and run application without user’s authorization. The downloaded apps will run with the set of permissions already requested by the downloader:

Through this malware, the attacker can easily get your personal information, contacts or even bank accounts and passwords. Also, the attacker can remotely control your phone to open specified application and perform some bad operations to make illicit profits.

Sample SHA256:
3cb7a4792725d381653fcca18d584f9fbe47d67f455db03e3c53e8e8e7736385

Analysis by Ruoxiao Wang

Published by

Nicolas Falliere

Author of JEB.

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