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Mohammad Waseem
Mohammad Waseem

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Securing Email Flows: A DevOps Approach to Validating Email Infrastructure Without Documentation

#devops #email #security

In today's rapidly evolving security landscape, ensuring the integrity of email flows is paramount. Yet, many organizations face the challenge of validating email infrastructure without comprehensive documentation, especially when deploying or auditing security measures in a DevOps environment.

This article discusses a pragmatic approach taken by a security researcher to secure and validate email flows using DevOps methodologies, despite the absence of proper documentation.

Understanding the Challenge

Without detailed diagrams or documentation, identifying the current state of email infrastructure—such as SMTP servers, spam filters, relay mechanisms, and recipient policies—becomes complex. The primary goal is to establish automated validation processes to monitor and secure email flows.

Step 1: Infrastructure Discovery

Begin by automating the discovery of email-related services and configurations.

# Using nmap to identify SMTP services
nmap -p 25,465,587 --script smtp-commands <target-ip-range>
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This scan reveals open SMTP ports and can help identify active mail servers. Additionally, querying DNS records helps reveal MX records.

# DNS lookup for MX records
dig MX domain.com
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Step 2: Configuration State Assessment

Automate retrieval of server configurations where possible. For example, using SSH or API endpoints, gather server settings—such as relay permissions, TLS configurations, and spam filter rules.

# Example: Access SMTP server configurations via command line or API
ssh user@mailserver "cat /etc/postfix/main.cf"
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Where documentation is missing, scripting these steps ensures consistency.

Step 3: Validate Email Flow Paths

Create test email flows to observe the behavior under various scenarios. Use scripting to send test emails through the discovered servers.

import smtplib
from email.message import EmailMessage

msg = EmailMessage()
msg.set_content("Test email")
msg['Subject'] = 'Validation Test'
msg['From'] = 'test@domain.com'
msg['To'] = 'recipient@anotherdomain.com'

with smtplib.SMTP('mailserver.domain.com', 587) as server:
    server.starttls()
    server.login('user', 'password')
    server.send_message(msg)
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Simultaneously, monitor logs and use network tools like tcpdump or Wireshark to verify if emails are relayed correctly.

Step 4: Automation and Continuous Validation

Integrate these discovery and validation steps into CI/CD pipelines. Use configuration management tools such as Ansible or Terraform to enforce desired configurations and run periodic tests.

# Example: Ansible playbook to validate SMTP configuration
- name: Check SMTP server configuration
  hosts: mailservers
  tasks:
    - name: Ensure SMTP port is open
      wait_for:
        port: 25
        state: started
        timeout: 5
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Use alerts to notify security teams about anomalies, such as unexpected open ports or misconfigurations.

Key Takeaways

  • Automate discovery to map existing infrastructure.
  • Use scripting to gather configurations where documentation is absent.
  • Create test flows to verify email relay, security protocols, and spam filtering.
  • Incorporate validation into CI/CD pipelines for ongoing assurance.

Validating email flows without documentation is challenging but achievable through systematic discovery, scripting, automation, and continuous monitoring. Employing DevOps principles allows security teams to adapt and respond swiftly, reinforcing the organization’s email security posture.

References:

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