HTTP Traffic Forensics: Red Flag

In this lab, you will receive network evidence captured in a .pcap file. This file contains an HTTP transaction between a client and a local server, and it is suspected that a flag is hidden within that communication.

In this lab you will learn:

• HTTP traffic analysis in .pcap files
• Using Wireshark for forensic inspection

🌱 How to start this lab

👉 This challenge is solved inside a preconfigured virtual machine with Wireshark and a graphical environment. No additional software installation or traffic simulation is required: you will analyze a pre-captured .pcap file directly.

1. If you don't have the virtual machine yet, download it from this link:

1https://storage.googleapis.com/cybersecurity-machines/redflag-lab.ova

1. Import the virtual machine into VirtualBox.
2. Start the VM and log in as user student:4geeks-lab.

Your Mission

An internal system made an HTTP request to a local server, which responded with unexpected content. The transmission was intercepted by a network sensor and is now in your hands: a .pcap file with the complete conversation. Your job as an analyst is clear: Examine the HTTP conversation for data that shouldn't be there.

It is rumored that the server delivered a suspicious string — there are no unusual headers, no obvious errors... just a simple response. But remember: simple things sometimes hide more than they show.

Tip: Sometimes messages are not in plain text, but masked with basic techniques like encoding. If you see a long, meaningless string... maybe it's not as random as it seems.

Validation

If, after decoding, the analyzed result has this format: 4GEEKS{EXAMPLE_FLAG}, then you have found what you were looking for.

Good luck, Forensic Analyst!