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N Ways to Unpack Mobile Malware

This article will briefly explain methods behind the mobile malware unpacking. It will be focusing on Anubis since it is the latest trending malware for almost a year now. Actors use dropper applications as their primary method of distribution. Droppers find their ways to Google Play store under generic names thereby infecting devices with Anubis. An example of a such dropper may found in the references. There were at least forty cases in Google Play in the last fall targeting Turkish users. @LukasStefanko’s twitter thread may be helpful to get an overview of such campaigns. Anubis malware already analysed by fellows from the industry in a detailed manner. Therefore readers should find it more valuable to have an article focusing on packer mechanisms of Anubis.

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Introducing New Packing Method: First Reflective PE Packer Amber

Because of the increasing security standards inside operating systems and rapid improvements on malware detection technologies today’s malware authors takes advantage of the transparency offered by in-memory execution methods. In-memory execution or fileless execution of a PE file can be defined as executing a compiled PE file inside the memory with manually performing the operations that OS loader supposed to do when executing the PE file normally. In-memory execution of a malware facilitates the obfuscation and anti-emulation techniques. Additionally the malware that is using such methods leaves less footprints on the system since it does not have to possess a file inside the hard drive. Combining in-memory execution methods and multi stage infection models allows malware to infect systems with very small sized loader programs; only purpose of a loader is loading and executing the actual malware code via connecting to a remote system. Using small loader codes are hard to detect by security products because of the purpose and the code fragments of loaders are very common among legitimate applications. Malware that are using this approach can still be detected with scanning the memory and inspecting the behaviors of processes but in terms of security products these operation are harder to implement and costly because of the higher resource usage (Ramilli, 2010[1]). Read More