Cobalt Strike stagers used by FIN6

In April, FireEye Managed Defense (or Mandiant) detected and described intrusion by FIN6 threat actor and their latest tactics, techniques, and procedures (TTPs). In particular, they used also LockerGoga and Ryuk ransomware families, and Cobalt Strike for initial compromise and lateral movement. Even three months after publishing their post, some of the URLs for Cobalt Strike stagers have been still active, so I decided to publish analysis of these Cobalt Strike stagers and payloads.
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Hunting for Blue Mockingbird samples

In my recent post about XMRig-based CoinMiners spread by Blue Mockingbird Group based mainly on Case Study by LIFARS I wrote about multi-stage attack performed by this threat actor. However, this case study doesn’t contain lot of IOCs (one reason could be to maintain privacy of the victims), and when I want to analyze these samples, first I have to find them somewhere. In this post I describe my process of searching for these samples using public services and how we can reconstruct the whole attack chain.
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Memory Acquisition on Synology NAS

As I stated in the post about Synology in VirtualBox, I wondered about forensic analysis of Synology NAS, especially about memory acquisition. As a part of preparation phase, I had to figure out how to create a Synology VM, because I did not have access to real Synology HW. Then I found the way how to create a memory dump in DSM 6.1.7 (from May 2018), but I wanted to verify my approach also in real HW with up-to-date version of DSM.
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XMRig-based CoinMiners spread by Blue Mockingbird Group

Overview During March-May the Blue Mockingbird group infected thousands of computer systems, mainly in the enterprise environment. There are known incidents in which they exploited the CVE-2019-18935 vulnerability in Telerik Web UI for ASP.NET, then they used various backdoors and finally, they deployed XMRig-based CoinMiners for mining Monero cryptocurrency. Interesting about these cases is the persistence which they used for CoinMiners - lot of techniques including scheduled tasks, services, but also WMI Event Subscription and COR Profilers.
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Phishing PDF Document Story

Background A few days ago, we detected a PDF file with a non-zero detection score on VirusTotal, however, almost all the detections have only a kind of “generic” results. Moreover, further investigation revealed that the same file was two weeks ago without any detections on VirusTotal. We continued with a deeper analysis of this document and its behavior to determine if this is only a false-positive alert, or if it can be a serious problem for those, who already opened this PDF document.
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