Results for apk

Threat Research

Unmasking Android Malware: A Deep Dive into a New Rootnik Variant, Part III

In this final blog in the Rootnik series we will finish our analysis of this new variant. Let’s start by looking into the script shell rsh. Analysis of the script shell Through our investigation we are able to see how the script shell works: First, it writes the content of the file .ir into /system/etc/install-recovery.sh. The file install-recovery.sh is a startup script. When the android device is booted, the script can be executed. The following is the content of the file .ir. Next, it writes some files...

By Kai LuJuly 09, 2017

Threat Research

Unmasking Android Malware: A Deep Dive into a New Rootnik Variant, Part II

In part I of this blog, I finished the analysis of the native layer of a newly discovered Rootnik malware variant, and got the decrypted real DEX file. Here in part II, we will continue our analysis. A look into the decrypted real DEX file The entry of the decrypted DEX file is the class demo.outerappshell.OuterShellApp. The definition of the class OuterShellApp is shown below. Figure 1. The class demo.outerappshell.OuterShellApp We will first analyze the function attachBaseContext(). The following is the function aBC() in the class...

By Kai LuJuly 09, 2017

Threat Research

BankBot, the Prequel

For us at FortiGuard, it always sounds like a bad idea for people to share malware source code, even if it is for academic or educational purposes. For example, on GitHub we can currently find more than 300 distinct repositories of ransomware, which gives you some idea about the attention that this form of malware receives. Although ransomware has the highest profile in the threat landscape at the moment, that does not mean that other threats have disappeared. Android is the most wide spread OS on mobile devices, covering around 80% of the...

Threat Research

How to repair a DEX file, in which some key methods are erased with NOPs

During the process of analyzing android malware, we usually meet some APK samples which hide or encrypt their main logic code.  Only at some point does the actual code exist in the memory, so we need to find the right time to extract it.  In this blog, I present a case study on how to repair a DEX file in which some key methods are erased with NOPs and decrypted dynamically when ready to be executed. Note: All the following analysis is based on android-4.4.2_r1(KOT49H). Let’s start our journey! First, I open the classes.dex...

By Kai LuApril 05, 2017

Threat Research

Android banking malware masquerades as Flash Player, targeting large banks and popular social media apps

Active users of mobile banking apps should be aware of a new Android banking malware campaign targeting customers of large banks in the United States, Germany, France, Australia, Turkey, Poland, and Austria. This banking malware can steal login credentials from 94 different mobile banking apps. Due to its ability to intercept SMS communications, the malware is also able to bypass SMS-based two-factor authentication. Additionally, it also contains modules to target some popular social media apps. Install the malware The malware masquerades...

By Kai LuNovember 01, 2016