SMTP Pentest Guide

Reporting Phase

The reporting phase is where you document and communicate your findings from the SMTP penetration test. A well-structured report is critical for helping stakeholders understand the issues discovered, their impact, and how to remediate them.

Components of an Effective SMTP Penetration Test Report

A comprehensive SMTP penetration test report should include the following sections:

1. Executive Summary

A high-level overview aimed at management and non-technical stakeholders.

  • Brief description of the assessment scope and objectives
  • Summary of key findings and their business impact
  • Overall risk rating for the SMTP infrastructure
  • High-level remediation recommendations
  • Graphics or charts showing vulnerability distribution by severity

2. Introduction and Scope

Detailed information about the assessment parameters.

  • Assessment objectives and methodology
  • In-scope SMTP servers and related infrastructure
  • Testing timeframe and constraints
  • Testing team and contact information
  • Tools and techniques used during the assessment

3. Findings and Vulnerabilities

Detailed description of each vulnerability discovered.

  • Title and unique identifier for each finding
  • Severity rating (Critical, High, Medium, Low)
  • Detailed technical description of the vulnerability
  • Steps to reproduce with command examples
  • Evidence (screenshots, logs, command output)
  • Business impact explanation
  • Detailed remediation recommendations
  • References to standards, CVEs, or best practices

4. Risk Assessment Methodology

Explanation of how risk was evaluated.

  • Risk rating system explanation (e.g., CVSS)
  • Factors considered in severity assessment
  • How business impact was determined
  • Explanation of likelihood and impact scales

5. Remediation Roadmap

Strategic plan for addressing identified vulnerabilities.

  • Prioritized list of remediation actions
  • Short-term quick wins vs. long-term improvements
  • Recommended timeline for implementation
  • Potential challenges or dependencies
  • Verification methods to confirm successful remediation

6. Appendices

Supporting information and detailed technical data.

  • Scan reports and raw output from tools
  • SMTP configuration best practices
  • Detailed explanation of testing methodology
  • Glossary of technical terms
  • References and resources for further information

Sample SMTP Vulnerability Report Entry

Finding: SMTP-001 - Mail Server Configured as Open Relay

Severity: Critical

Affected Systems: mail.example.com (192.0.2.1), Port 25

Description:

The SMTP server at mail.example.com is configured to relay messages from any source to any destination, making it an "open relay." This allows unauthenticated users to send emails through the server without authorization.

Evidence:

$ telnet mail.example.com 25 220 mail.example.com ESMTP Postfix HELO pentest.local 250 mail.example.com MAIL FROM: <external@attacker.com> 250 2.1.0 Ok RCPT TO: <victim@another-domain.com> 250 2.1.5 Ok DATA 354 End data with <CR><LF>.<CR><LF> Subject: Test Open Relay This is a test message sent through an open relay. . 250 2.0.0 Ok: queued as A1B2C3D4E5 QUIT 221 2.0.0 Bye

Business Impact:

An open relay can be exploited by malicious actors to:

  • Send spam or phishing emails appearing to come from your organization
  • Lead to your mail servers being blacklisted by spam filters
  • Damage the organization's reputation
  • Potentially lead to legal issues if used for illegal activities

Remediation:

  1. Configure the SMTP server to only relay messages for authenticated users and trusted networks
  2. For Postfix, update the smtpd_relay_restrictions setting in main.cf:
    smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
  3. Define mynetworks to include only trusted internal networks
  4. Implement proper SMTP authentication for legitimate users
  5. After changes, test to verify the server no longer allows unauthorized relaying

References:

Tips for Effective Reporting

  1. Know your audience - Tailor different sections for technical and non-technical readers
  2. Provide context - Explain why each vulnerability matters to the business
  3. Be specific - Include exact commands, configurations, and evidence
  4. Avoid jargon - Define technical terms when they must be used
  5. Prioritize clearly - Help readers understand what to fix first
  6. Include verification steps - Describe how to confirm successful remediation
  7. Use visual aids - Charts, screenshots, and diagrams improve understanding
  8. Be constructive - Focus on improvement rather than criticism

Presentation of Findings

In addition to the written report, consider how to effectively present findings to stakeholders:

  • Executive briefing - Concise presentation for management focusing on business impact and risk
  • Technical walkthrough - Detailed session with the IT/security team demonstrating vulnerabilities
  • Remediation workshop - Collaborative session to develop and refine action plans
  • Follow-up sessions - Check-ins to assess remediation progress and answer questions

Post-Report Activities

The reporting phase is not the end of the penetration testing process:

  • Be available for questions - Offer to clarify any findings or recommendations
  • Provide remediation support - Offer guidance as the team implements fixes
  • Verification testing - Conduct follow-up testing to confirm issues are resolved
  • Knowledge transfer - Help the team understand how to prevent similar issues
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