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Mohammad Waseem
Mohammad Waseem

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Automating Authentication Flows in Legacy Codebases with DevOps: A Security Researcher’s Approach

#devops #automation #security

Introduction

Legacy systems often pose significant challenges when it comes to implementing modern security and automation practices. Authentication (auth) flows, in particular, tend to be tightly coupled with outdated code and practices, making them difficult to modify or update without risking system stability. This blog details a security researcher’s approach to automating auth flows within legacy codebases by leveraging DevOps principles, scripting, and containerization — ensuring both security and efficiency.

The Challenge of Legacy Authentication

Many legacy applications rely on static, hard-coded authentication methods or outdated protocols that are incompatible with modern authentication standards like OAuth2 or OIDC. These systems may lack APIs or hooks for easy automation, and rewriting the entire auth system might be infeasible.

The goal becomes: how can we automate user login flows, token management, and session validation without a complete overhaul?

Strategy Overview

The researcher’s approach involves the following core components:

  • Reverse engineering and extracting auth logic
  • Creating automation scripts to simulate user flows
  • Containerizing automation workflows for repeatability
  • Integrating with CI/CD pipelines for ongoing security validation

Let’s explore each step.

Step 1: Reverse Engineering Auth Flows

Identify how users authenticate within the legacy system. This involves analyzing network traffic, logs, and the code itself. For example, using tools like Burp Suite or Fiddler, inspect the requests involved during login.

# Example: capturing authentication request
curl -v 'http://legacy-app.local/login' -X POST \
--data-urlencode 'username=admin' --data-urlencode 'password=legacy123'
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This reveals the exact payload, headers, and responses. Understanding the flow allows scripting of login automation.

Step 2: Automating User Authentication

Create scripted automation of login flows. By mimicking the request structure, scripts can be written in languages like Python or Bash.

import requests

session = requests.Session()
login_payload = {
    'username': 'admin',
    'password': 'legacy123'
}
response = session.post('http://legacy-app.local/login', data=login_payload)
if response.ok:
    print('Login successful')
    # Save cookies/token for subsequent requests
else:
    print('Login failed')
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This script can be extended to handle token refresh, session validation, and error handling.

Step 3: Containerizing Automation with Docker

To ensure repeatability and security, encapsulate scripts within Docker containers.

FROM python:3.10-slim
WORKDIR /app
COPY login_script.py ./
RUN pip install requests
CMD ["python", "login_script.py"]
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Build and run the container:

docker build -t auth-auto .
docker run --rm auth-auto
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Containerization isolates the automation environment and makes it easier to deploy across different systems.

Step 4: Integrating into DevOps Pipelines

Finally, embed these containers within CI/CD workflows to validate auth flows on each deployment.

jobs:
  authenticate:
    runs-on: ubuntu-latest
    steps:
    - name: Checkout code
      uses: actions/checkout@v2
    - name: Build Docker image
      run: |
        docker build -t auth-auto .
    - name: Run automation script
      run: |
        docker run --rm auth-auto
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This ensures that authentication flows are tested automatically, reducing security risks and ensuring compliance.

Conclusion

By reverse engineering legacy auth flows, scripting simulations, and leveraging containerized DevOps practices, security researchers can effectively automate and modernize authentication in outdated systems. While care must be taken to respect security and operational constraints, this methodology provides a scalable, repeatable approach to managing legacy authentication workflows.

Final Notes

  • Always ensure sensitive data like credentials are stored securely.
  • Validate automation scripts thoroughly to prevent unintentionally locking users out.
  • Gradually integrate these techniques into broader security testing frameworks.

Embracing DevOps and automation in legacy contexts not only enhances security but also fosters a pathway toward incremental modernization without disrupting core functionalities.

🛠️ QA Tip

I rely on TempoMail USA to keep my test environments clean.

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