Thanks to everyone who participated in the May 2021 forensic contest originally posted two weeks ago. We received 45 submissions through our contact page, and most people had all the correct answers. Unfortunately, we could only pick one winner. In this case, our winner was the first to submit the correct information. Join us in congratulating this month’s winner, Pratik! Pratik will receive a Raspberry Pi 4 kit.
You can still find the pcap for our May 2021 forensic contest at this Github repository.
IP address of the infected Windows computer:
Host name of the infected Windows computer:
User account name on the infected Windows computer:
Date and time the infection activity began in UTC (the GMT or Zulu timezone):
2021-05-04 at 22:16:52 UTC
The family or families of malware on the infected computer:
To help in your analysis of this activity, please review the Requirements section in our original diary for this contest.
Malware from the pcap
The iniitial malware activity in the pcap is seen when the victim’s host retreived a Windows EXE or DLL from 185.183.99[.]115 on 2021-05-04 at 22:16:52 UTC.
The URL hosting this malware was reported to URLhaus, where it is tagged as Qakbot malware. The IP address is also related to some malicious Excel spreadsheets with file names that start with Outstanding-Debt- and end with 05042021.xlsm.
Shown above: Malicious Excel files submitted to Hatching Triage that contacted 185.183.99[.]115.
Here’s a Wireshark filter I use to review suspected Qakbot traffic:
Qakbot causes HTTPS C2 traffic directly to IP addresses, often over TCP port 443, but also using non-standard HTTPS ports like 995 or 2222. Qakbot also generates other traffic when it turns an infected Windows host into a spambot. Using the above Wireshark filter, I can quickly find the following Qakbot activity:
Connectivity check to www.openssl.org (a legitimate site, not inherently malicious on its own)
TCP traffic over TCP port 65400
Connectivity/ IP address checks to api.ipifiy.org (also a legitimate site, not inherently malicious)
Connectivity or banner checks to various email servers
SMTP-based spambot traffic from the infected host
Use a basic web filter and scroll down to the end of the pcap. You should see indicators the infected host became a spambot and was contacting various email servers over TCP ports 25 and 465.
Qakbot infection activity follows noticeable patterns, which we covered in today’s diary. The traffic isn’t much different than cases I’ve reported before, like this example from February 2021.
Thanks to all who participated in the May 2021 forensic contest, and congratulations again to Pratik for winning this month’s competition!
You can still find the pcap and malware at this Github repository.
brad [at] malware-traffic-analysis.net
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Source: Read More (SANS Internet Storm Center, InfoCON: green)