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Reverse Engineering Malware

Featuring 1 Paper as of April 22, 2019

  • Unpacking & Decrypting FlawedAmmyy by Mike Downey - April 22, 2019 

    Malware authors commonly utilize packers (Roccia, 2017) as a method of concealing functionality and characteristics of their malicious code, making an analystís job more difficult. Second stage executables may also be encrypted, requiring the analyst to gather an understanding of how this code is manipulated. The ability to unpack and decrypt malicious software is a critical step in understanding intent and the scope of malware capabilities. The goal of this paper is to provide real-world application of the unpacking and decoding techniques required to analyze a remote access Trojan (RAT) known as FlawedAmmyy. While basic static and dynamic analysis will not be covered, this paper will focus on the step-by-step procedures to unpack and decrypt a FlawedAmmyy sample within a debugger.

Most of the computer security white papers in the Reading Room have been written by students seeking GIAC certification to fulfill part of their certification requirements and are provided by SANS as a resource to benefit the security community at large. SANS attempts to ensure the accuracy of information, but papers are published "as is". Errors or inconsistencies may exist or may be introduced over time as material becomes dated. If you suspect a serious error, please contact

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STI Graduate Student Research - This paper was created by a SANS Technology Institute student as part of the graduate program curriculum.