Tracing Spoofed Emails

Techniques for Cybersecurity Professionals

Email spoofing is a common tactic in phishing and fraud campaigns. This post breaks down how to identify and trace spoofed emails.

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1. What is Email Spoofing?

• Definition: Sending an email with a falsified sender address.
• Common methods:
  • Open relay servers.
  • Compromised mail servers.

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2. Anatomy of an Email Header

• Key fields to analyze:
  • Received: Tracks the email’s journey.
  • From: Often forged.

Example Header Analysis:

textCopy codeReceived: from fake.mail.com by victim.com  

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3. Tools for Tracing Spoofed Emails

• nslookup: Resolve IP addresses to domain names.
• whois: Retrieve domain ownership information.
• traceroute: Trace the path of packets to the source.

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4. Identifying Spoof Indicators

• Mismatched timestamps.
• Suspicious IP ranges in Received headers.

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Tools Explained:

1. nslookup
   • What It Does: Resolves domain names to IP addresses.
   • Use Case: Confirm the validity of email domains.
2. whois
   • What It Does: Retrieves domain registration details.
   • Use Case: Identify ownership of suspicious domains.
3. traceroute
   • What It Does: Maps the path of packets to their destination.
   • Use Case: Trace the origin of spoofed email servers.

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5. Case Study: Unmasking a Phishing Campaign
Scenario: Employees report a phishing email claiming to be from a bank.
Solution: Analyze the email header:

1. Extract the “Received” field to locate the origin IP.
2. Use nslookup to verify the IP:bashCopy codenslookup 192.168.1.1
3. Use whois to investigate the domain ownership:bashCopy codewhois maliciousdomain.com
4. Use traceroute to determine the email’s route:bashCopy codetraceroute maliciousdomain.com
5. Report the malicious server to the relevant authorities.

Understanding email headers and using tracing tools can help combat email-based attacks.