lunes, 13 de mayo de 2019

Quick Analysis of AgentTesla SMTP Variant Sample (dated 08-05-2019)

In this post I perform a quick analysis of a recent AgentTesla SMTP variant sample, paying special attention to the strings decryptor (most of the interesting information is kept as encrypted strings, smtp server and mail address included), in an attempt for documenting a bit more the decompiled source code with references to the decrypted strings where they are used, to understand how the malware works.


lunes, 15 de abril de 2019

Analysis of .Net Deucalion IrcBot Sample Obfuscated with ConfuserEx+KoiVM

In this post I perform a quick analysis of a sample that seems to be an ircbot, named alphaircbot (based on the any.run tags) or deucalion (based on the internal .net classes names and deobfuscated strings). The malware family itself doesn't seem specially interesting, however, it is obfuscated with ConfuserEx obfuscator + KoiVM virtualization.

It was quite hard for me to deal with the obfuscated code, and debug it with dnSpy or similar tools to get the original assembly. I decided to use Windbg's sos extension to walk the loaded assemblies and to find the dynamic assemblies belonging to the original malware code. With this extension it is possible to enum the method tables foreach assembly and the stacks foreach thread that is executing managed code, making easy to find jit generated code that belongs to the malware code (and interesting malware's data referenced by the jit generated code).


  • Original Packed Sample: 40e751c032c75d33c807219b2de6c584
  • Source Url: hxxp://54.38.22[.]53/spike/svchost.exe
  • Info Url: URLhaus
  • Automatic Generated Report: PepperMalware Report
  • Virustotal First Submission: 2018-06-10 16:37:46
  • Other AlphaIrcbot samples at Any.Run: 

  • asdjdsffdgnms.exe (2018-08-19 10:25:54)
  • KFDJfd.exe (2018-11-16 00:26:10)
  • jjunpkvyalquru.exe (2018-09-01 21:40:15) 

  • Any.Run Tags: alphaircbot
  • Related links:

  • https://hackforums.net/showthread.php?tid=5875152 
  • http://offensivecommunity.net/showthread.php?tid=76358
  • https://urlhaus.abuse.ch/browse/tag/AlphaIRCBot/ 
  • https://yck1509.github.io/ConfuserEx/ 
  • https://github.com/Loksie/KoiVM-Virtualization
  • https://docs.microsoft.com/en-us/dotnet/framework/tools/sos-dll-sos-debugging-extension 
  • https://docs.microsoft.com/en-us/windows-hardware/drivers/debugger/debugging-managed-code 
  • https://mindlocksite.wordpress.com/2017/02/11/easy-way-to-unpack-confuserex-1-0-max-settings/ 
  •  https://github.com/CodeCracker-Tools/MegaDumper



  • viernes, 22 de marzo de 2019

    Analysis of .Net Stealer GrandSteal (2019-03-18)

    In this post I share my notes about the analysis of a sample (an stealer written in .Net) whose family is unknown to me (any feedback is welcome, if you know the family for the sample that I describe, please tell me and I will update this post). Somebody tagged the sample as quasar at Any.Run, however, after analyzing it and comparing with Quasar code, I concluded this sample doesn't seem to belong to Quasar family. Searching information about the collected IoCs was not successful to classify the sample. I am calling it GrandSteal because of the internal names of the .Net classes of the malware's decompiled code.


    • Original Packed Sample: 89782B6CDAAAB7848D544255D5FE7002
    • Source Url: http://a4.doshimotai[.]ru/pxpx.exe
    • Info Url: VxVault URLhaus
    • Automatic Generated Report: PepperMalware Report
    • Virustotal First Submission: 2019-03-18 22:28:20
    • Any.Run Analysis: Here
    • Any.Run Tags: Evasion, Trojan, Rat, Quasar
    • My Classification: I named it GrandSteal because of the internal .Net classes names (if you have any information about any well-known family that this malware belongs to, please, tell me and I will update this post)
    • Decompiled Source Code: PepperMalware Github

    lunes, 18 de marzo de 2019

    Analysis of BlackMoon (Banking Trojan)'s Evolution, And The Possibility of a Latest Version Under Development

    BlackMoon, also known as KrBanker, is a banking trojan that mainly targets South Korea. I thought this family was dead since time ago (around 2016), however these previous days I got a couple of rencent samples that, after unpacking them and performing a quick analysis, I noticed they were BlackMoon. Virustotal's first submission date for one of these samples is 2018-06-18. First submission date for the other one is 2018-11-01. After digging a bit more into this malware family, my conclussion was that probably there is a latest version of BlackMoon that is under development. I explain it in this post, that I hope you enjoy.

    martes, 5 de marzo de 2019

    Quick Analysis of a Trickbot Sample with NSA's Ghidra SRE Framework

    This post is not a deep analysis of TrickBot. Here, I did a quick analysis of a TrickBot sample from early 2019 by using the Ghidra Software Reverse Engineering (SRE) Framework, developed by the NSA, that was released some hours ago. This is not a deep analysis of TrickBot, I only wanted to learn a bit about Ghidra and I used this framework to find some interesting parts of the code of TrickBot that were introduced in the newer versions of the malware. Hope you enjoy it!

    miércoles, 2 de enero de 2019

    Analysis of Neutrino Bot Sample (dated 2018-08-27)

    In this post I analyze a Neutrino Bot sample. It was probably generated 2018-08-27. I will compare the analyzed Neutrino sample with the NukeBot's source code that was leaked on spring, 2017, and I will check that Neutrino Bot is probably an evolution (or, at least, it reuses parts) of the NukeBot leaked code.