Email Forensics

Email Investigation and Digital Evidence Analysis

Security Threat Model

What is Email Forensics?

Email Forensics: The process of examining email communications, headers, attachments, and related metadata to gather digital evidence for investigations and legal proceedings.
  • Header Analysis: Examining email routing and metadata
  • Content Investigation: Analyzing message content and attachments
  • Authentication Verification: Determining email authenticity
  • Timeline Reconstruction: Building communication chronology

Email System Components

Email Header Analysis

Email Headers: Metadata containing routing information, timestamps, and technical details about email transmission and handling.
Key Header Fields: From: sender@domain.com To: recipient@domain.com Subject: Email subject line Date: Timestamp when email was sent Message-ID: Unique identifier for the message Received: Server routing information (multiple entries) Return-Path: Bounce address for delivery failures Content-Type: Message format and encoding

Header Analysis Benefits:

  • Trace email routing path
  • Verify sender authenticity
  • Identify tampering attempts
  • Determine transmission times
  • Locate originating servers

Email Authentication Mechanisms

Email Spoofing Detection

Spoofing Indicators:

  • Header Inconsistencies: Mismatched From and Return-Path fields
  • Authentication Failures: Failed SPF, DKIM, or DMARC checks
  • Routing Anomalies: Unusual server paths or geographic inconsistencies
  • Display Name Tricks: Misleading sender display names
  • Domain Variations: Typosquatting and homograph attacks
Authentication Results Header: Authentication-Results: mx.google.com; spf=pass smtp.mailfrom=sender.com; dkim=pass header.i=@sender.com; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=sender.com

Email Client Forensics

Microsoft Outlook Forensics:

  • PST Files: Personal Storage Table files containing emails
  • OST Files: Offline Storage Table cached data
  • Registry Entries: Account settings and configurations
  • Autocomplete Files: NK2/Stream_Autocomplete_* files
  • Deleted Items: Recoverable items folder analysis
PST File Analysis: • Use tools like Kernel PST Viewer, SysTools PST Viewer • Extract emails, contacts, calendar items • Recover deleted items from unallocated space • Analyze folder structures and permissions • Export to standard formats (MSG, EML, MBOX)

Webmail Forensics

Gmail Investigation:

  • Google Takeout data exports
  • Gmail API for programmatic access
  • Browser extension data
  • Mobile app data analysis
  • Account activity logs

Email Server Forensics

Server-Side Analysis: Examining email servers, logs, and backend systems for comprehensive email forensics.

Server Log Analysis:

  • SMTP connection logs
  • Authentication attempt records
  • Message delivery status
  • Bounce and error messages
  • Relay and routing information

Email Attachment Analysis

Attachment Investigation:

  • File Type Analysis: Verify file signatures and extensions
  • Malware Scanning: Check for malicious content
  • Metadata Extraction: EXIF data, document properties
  • Content Analysis: Embedded objects and macros
  • Hash Verification: File integrity and comparison
Common Attachment Types: • Documents: PDF, DOC, XLS, PPT • Images: JPEG, PNG, GIF, TIFF • Archives: ZIP, RAR, 7Z • Executables: EXE, DLL, SCR • Scripts: JS, VBS, PS1, BAT • Email: EML, MSG (forwarded emails)

Email Timeline Analysis

Timeline Reconstruction:

  • Sent Times: When emails were composed and sent
  • Received Times: Server timestamps for message receipt
  • Read Receipts: When recipients opened messages
  • Delivery Reports: Message delivery confirmations
  • Access Logs: When mailboxes were accessed

Timeline Correlation:

  • Cross-reference with system events
  • Match with network access logs
  • Correlate with user activity patterns
  • Identify time zone differences
  • Detect scheduling patterns

Deleted Email Recovery

Exchange Recovery Commands: Get-MailboxFolderStatistics -Identity user@domain.com -FolderScope RecoverableItems Search-Mailbox -Identity "User Name" -SearchDumpster -TargetMailbox "Discovery Mailbox" Get-MailboxSearch -Identity "Search Name" | FL

Email Forensic Tools

Email Encryption Analysis

Encrypted Email: Messages protected using cryptographic methods to ensure confidentiality and integrity.

Encryption Types:

  • S/MIME: Secure/Multipurpose Internet Mail Extensions
  • PGP/GPG: Pretty Good Privacy encryption
  • TLS: Transport Layer Security for transmission
  • O365 Encryption: Microsoft's email protection
  • ProtonMail: End-to-end encrypted email service

Investigation Approaches:

  • Private key recovery from endpoints
  • Certificate and key store analysis
  • Metadata analysis of encrypted messages
  • Sender/recipient correlation analysis
  • Legal process for service providers

Email Threat Investigation

Threat Indicators: • Suspicious sender domains • Unusual attachment types • Urgent or threatening language • Requests for sensitive information • Links to suspicious websites • Grammar and spelling errors • Mismatched URLs and display text

Legal Discovery and eDiscovery

eDiscovery Process:

  1. Identification: Locate relevant email sources
  2. Preservation: Legal hold implementation
  3. Collection: Gather emails from various sources
  4. Processing: De-duplicate and organize messages
  5. Review: Analyze for relevance and privilege
  6. Production: Deliver in requested format

Discovery Challenges:

  • Volume and scalability issues
  • Privileged communication identification
  • Multi-platform email systems
  • International data location
  • Mobile device email access

Email Privacy and Legal Issues

Privacy Considerations:

  • Expectation of Privacy: Personal vs. corporate email
  • Attorney-Client Privilege: Protected communications
  • Employee Monitoring: Workplace email surveillance
  • International Laws: GDPR and data protection
  • Consent Requirements: Lawful interception needs

Legal Best Practices:

  • Obtain proper legal authorization
  • Maintain detailed chain of custody
  • Document all analysis procedures
  • Protect privileged communications
  • Follow data retention policies

Advanced Email Analysis

Metadata Analysis: • X-Originating-IP headers • User-Agent strings • Time zone analysis • Language and encoding patterns • Routing path analysis • Server infrastructure mapping

Email Forensic Reporting

Report Components:

  • Executive Summary: High-level findings and conclusions
  • Technical Analysis: Detailed examination results
  • Timeline: Chronological sequence of events
  • Evidence Inventory: List of examined emails and sources
  • Methodology: Tools and techniques used
  • Appendices: Screenshots, headers, and supporting data

Reporting Standards:

  • Clear and objective language
  • Proper technical documentation
  • Visual aids and diagrams
  • Reproducible methodology
  • Expert qualification statements

Future of Email Forensics

Emerging Challenges:

  • AI-Generated Content: Deepfake emails and content
  • Quantum Cryptography: Quantum-resistant encryption
  • Ephemeral Messaging: Self-destructing messages
  • Federated Identity: Cross-platform authentication
  • Cloud-Only Services: Limited local storage

Technology Evolution:

  • AI-powered email analysis
  • Blockchain-based email verification
  • Real-time threat detection
  • Advanced authentication methods
  • Cross-platform investigation tools

Key Takeaways

Critical Points:

  • Comprehensive Analysis: Header, content, and metadata examination
  • Authentication Verification: SPF, DKIM, DMARC validation
  • Multi-Source Investigation: Client, server, and network analysis
  • Legal Compliance: Privacy and discovery requirements
  • Timeline Accuracy: Proper time zone and chronology analysis
Email Forensics Excellence: Combine technical expertise in email systems, proper legal authorization, and systematic analysis methods to effectively investigate email communications and provide reliable digital evidence.