Using Wireshark to Identify Malicious Network Activity

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Using Wireshark to Identify Malicious Network Activity

In this lab, we will learn how to use Wireshark to identify malicious network traffic. We will download two packet captures and analyze them, checking for signs of beaconing and exfiltration via DNS tunneling.

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Lab Info

Level

Beginner

Last updated

Sep 19, 2025

Duration

30m

Challenge

Install Wireshark.
1. Use your preferred VNC client to connect to the host using the provided public IP on port 5901.
2. Run the commands sudo apt-get update and sudo apt-get install -y wireshark.
3. When asked if you want to allow non-superusers to capture packets, select Yes.
Challenge

Download and analyze packet captures.
Download the following PCAP files to the Downloads directory:
- https://github.com/linuxacademy/content-cysa-wiresharkanalysis/blob/master/dns-tunneling.pcap
- https://github.com/linuxacademy/content-cysa-wiresharkanalysis/blob/master/beaconing.pcap
Challenge

Create the firewall rules.
1. Use Gedit to create a file named firewall-rules.txt and save it on the Desktop.
2. Review the two packet captures and identify the source and destination involved in beaconing and DNS tunneling, and create a rule for each of the two activities.
3. The firewall-rules.txt file should contain two access lists which following the format outlined in the Guide. Remember Linux is case sensitive.
4. The firewall rule to block beaconing is:
  access-list BLOCK deny TCP 192.168.122.212/32 188.120.247.14/32 eq 80
5. The firewall rule to block DNS tunneling is:
  access-list BLOCK deny UDP 10.0.2.30/32 10.0.2.20/32 eq 53

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