CHFI (312-49) Digital Forensics Simulation

Welcome to this network forensics simulation. You will analyze captured network traffic to isolate specific application-layer artifacts, a critical skill for examining data exfiltration and C2 communications.

Investigation Scenario

During a digital forensics investigation of a corporate breach in Atlanta, Georgia, preliminary evidence indicates that unauthorized data exfiltration occurred over HTTP. The network administrator provided an offline packet capture (PCAP) acquired from the perimeter span port during the suspected incident window. The investigator suspects the data was sent to the domain example.com.

Evidence Collected

Item Number: EVD-2023-094-NET
Evidence Type: Network Packet Capture (.pcapng)
Hash (SHA-256): 8a42b98f2...
File Size: 1.2 GB (approx. 2.4 million frames)

[Investigator Terminal Session]
> file evidence_001.pcapng
evidence_001.pcapng: pcapng capture file - version 1.0
> capinfos evidence_001.pcapng
File name: evidence_001.pcapng
Data size: 1.2 GB
Encapsulation: Ethernet
Protocols identified: ETH, IPv4, TCP, UDP, DNS, HTTP, TLS

Question

During a network-forensics investigation in Atlanta, Georgia, an analyst is using Wireshark to capture and analyze network traffic. The analyst wants to filter the traffic to show only HTTP requests made to a specific domain. Which Wireshark display filter should be used?

A. http.host == "example.com"
B. tcp.port == 80
C. ip.addr == 192.168.1.1
D. eth.addr == 00:11:22:33:44:55
Investigative Hint: You need to filter based on a specific domain name (the "Host" value in the application layer protocol), not a transport layer port, network IP address, or physical MAC address.

Expert Analysis

1. What the evidence shows

The collected 1.2 GB PCAP file contains a massive volume of mixed network traffic. Analyzing raw frames without precise application-layer filters is computationally expensive and cognitively overwhelming for an investigator.

2. Forensic Stage

Examination and Analysis. The physical data has already been preserved and collected. The current objective is to carve and isolate relevant digital artifacts (HTTP requests) from the raw binary capture.

3. Why the correct answer is correct (A)

The filter http.host == "example.com" explicitly parses OSI Layer 7 (Application Layer) and filters the output to only show frames where the HTTP "Host" header exactly matches the target domain. This isolates the specific C2/exfiltration traffic regardless of the IP address the domain resolves to.

4. Why others are wrong

  • B. tcp.port == 80: This filters by transport layer (Layer 4). It will show all unencrypted web traffic to any domain, introducing massive amounts of noise (irrelevant evidence) into the analysis.
  • C. ip.addr == 192.168.1.1: This filters by network layer (Layer 3). CDNs and cloud hosts often use dynamic IPs, or multiple domains may share a single IP. It does not target the specific application payload.
  • D. eth.addr == ...: This filters by data link layer (Layer 2) physical MAC address. It only tracks a local physical interface (like a router or local NIC) and reveals nothing about the destination domain.

5. Real-World Forensic Action

In practice, once the investigator applies the http.host filter to isolate the malicious frames, they will right-click the packet, select "Follow > HTTP Stream" to view the raw GET/POST requests and responses, and then use File > Export Objects > HTTP to extract exfiltrated files or downloaded malware payloads for offline hashing and static analysis.

MINI LESSON: Artifact Interpretation & Filtering

Digital forensics demands precision. When isolating artifacts, investigators must align their search criteria with the correct OSI layer. Network protocols are encapsulated. Searching for a domain name (Layer 7 data) using a Layer 3 (IP) or Layer 4 (Port) filter is a common analytical error that violates the principle of exact artifact isolation. Always use protocol-specific parsers in your examination tools to establish an accurate and irrefutable chain of evidence.

Master Digital Forensics

Enhance your evidence analysis skills and prepare for the CHFI exam with realistic scenarios.

Explore more CHFI simulations