Getting Closer - HackTheBox Challenge Writeup

Challenge Information

Description

In this forensics challenge, you’re tasked with analyzing a file to detect a stealthy cyber attack that penetrated the defenses of Hackster’s University students who were working to protect antidote research. The challenge emphasizes the importance of analyzing suspicious files to identify attack patterns and indicators of compromise that might go unnoticed.

Note: The challenge requires modifying /etc/hosts to map discovered hostnames to the Docker instance IP address.

Challenge Approach

This is a forensics challenge that requires:

1. Obtaining the target file from the challenge instance at 154.57.164.66:30340
2. Analyzing the file for signs of compromise or stealthy attack indicators
3. Identifying hostnames and configuring them in /etc/hosts to point to the Docker IP
4. Extracting forensic artifacts that reveal the nature of the attack

Solution Methodology

Step 1: Access the Challenge Instance

Connect to the provided target instance to retrieve the file that needs analysis:

# Access the challenge instance
# Note: Replace with actual connection method once instance details are available
nc 154.57.164.66 30340

# Or via HTTP/web interface if applicable
curl http://154.57.164.66:30340/

Step 2: Analyze the Retrieved File

Once you obtain the suspicious file, perform forensic analysis:

# Check file type and properties
file suspicious_file

# View file contents (if text-based)
cat suspicious_file

# Perform hex dump for binary analysis
xxd suspicious_file

# Search for embedded strings that might indicate malicious activity
strings suspicious_file

Step 3: Identify Hostnames and Configure /etc/hosts

If the analysis reveals hostnames or domain names:

# Edit the hosts file to map discovered hostnames
sudo nano /etc/hosts

# Add entries mapping hostnames to the Docker IP
# Example format:
# 154.57.164.66  hostname1.local
# 154.57.164.66  hostname2.local

Step 4: Extract and Validate Findings

Use forensic tools to extract artifacts:

# Common forensics tools depending on file type
# For memory dumps:
volatility -f memory_dump --profile=LinuxProfile pslist

# For file system artifacts:
foremost -i suspicious_file -o output_directory

# For network indicators:
grep -r "suspicious_pattern" .

Tools Used

• Standard Linux utilities: file, strings, xxd, cat, grep
• Forensics frameworks: Volatility (for memory analysis)
• File carving: Foremost (for extracting embedded files)
• Text editors: nano/vim (for /etc/hosts modification)

Key Learnings

1. File Analysis Fundamentals: Understanding file types and structures is crucial for identifying embedded malicious content or indicators of compromise

2. String Extraction: Using strings to identify readable text in binary files often reveals command-and-control servers, malicious domains, or attack signatures

3. Hostname Enumeration: Stealthy attacks often use DNS or domain-based communications; identifying and resolving these hostnames is essential for understanding attack infrastructure

4. /etc/hosts Manipulation: Local DNS resolution through /etc/hosts is a key forensics technique for simulating attacker infrastructure without actual network connections

5. Holistic Analysis: Forensics challenges require combining multiple analysis techniques—binary analysis, string extraction, artifact recovery, and infrastructure mapping—to build a complete picture of the attack

Conclusion

The “Getting Closer” challenge emphasizes the importance of meticulous file analysis in detecting sophisticated attacks. By combining standard forensic tools with careful examination of binary and textual artifacts, defenders can identify attack infrastructure and indicators of compromise that might otherwise remain hidden.