This is a submission for DEV's Summer Bug Smash: Clear the Lineup powered by Sentry.
Project Overview
Project: A Footballer's Delicacy
Website: https://www.afootballersdelicacy.com/
A Footballer's Delicacy is an existing web application that I worked on from a cybersecurity and application-hardening perspective.
The goal of the work was to identify security weaknesses in the existing application and remediate them without introducing unrelated functionality. I performed security-focused testing and code review, investigated the behavior of the application, identified vulnerable or unsafe implementation patterns, and implemented fixes directly in the existing codebase.
The work covered several areas of web application security, including input validation, database security, authentication and sessions, request protection, access control, HTTP security headers, information disclosure, and abuse prevention.
Bug Fix or Performance Improvement
The security review identified multiple areas where the existing implementation could be strengthened.
1. SQL Injection Risk
Some database operations required stronger protection against user-controlled input.
Fix: Replaced unsafe query construction with parameterized/prepared statements and improved validation of database inputs.
2. Cross-Site Scripting (XSS)
User-controlled data was reviewed to ensure that untrusted values could not be rendered directly into HTML or other executable contexts.
Fix: Added appropriate server-side validation and contextual output encoding/escaping.
3. Cross-Site Request Forgery (CSRF)
State-changing requests were reviewed for request-origin authenticity.
Fix: Implemented CSRF tokens for applicable forms and state-changing operations and verified tokens server-side.
4. Security Headers
The application did not have sufficient protection against several browser-based attack techniques.
Fix: Strengthened HTTP response security headers, including controls related to clickjacking, MIME-type sniffing, and browser security policies.
5. Session Security
Authentication/session handling was reviewed for weaknesses that could increase the impact of session theft or fixation.
Fix: Hardened session configuration and cookie security attributes and improved session lifecycle handling.
6. Information Disclosure
Error responses and application behavior were reviewed for unnecessary technical information that could assist an attacker.
Fix: Reduced unnecessary error details exposed to users while retaining appropriate diagnostic information for developers and monitoring.
7. Input Validation
Several application inputs required stronger server-side validation rather than relying only on client-side controls.
Fix: Added validation at the server boundary and rejected malformed, unexpected, or invalid input before further processing.
8. Rate Limiting and Abuse Prevention
Security-sensitive endpoints were reviewed for automated abuse and excessive request activity.
Fix: Added or strengthened rate-limiting controls where appropriate to reduce brute-force and automated-abuse risks.
9. Access Control Review
Existing endpoints and operations were reviewed to ensure that users could not access functionality or resources outside their intended authorization level.
Fix: Added authorization checks where required and ensured that sensitive operations were not protected solely by client-side controls.
10. Directory and File Exposure
The application was reviewed for unnecessarily accessible files, directories, configuration information, and development artifacts.
Fix: Restricted unnecessary exposure and removed or protected files that should not be publicly accessible.
11. Server and Technology Information Disclosure
The application and HTTP responses were reviewed for unnecessary server/version information.
Fix: Reduced unnecessary technology and version disclosure where possible.
12. CORS and Browser-Origin Controls
Cross-origin behavior was reviewed to ensure that browser requests were not unnecessarily trusted.
Fix: Restricted cross-origin behavior to the required origins and avoided unnecessarily permissive configurations.
Code
One example of the remediation was improving database query handling.
Before
```php id="s9x4v8"
$query = "SELECT * FROM messages WHERE email = '$email'";
$result = mysqli_query($connection, $query);
### After
```php id="k5m1ra"
$stmt = $connection->prepare(
"SELECT * FROM messages WHERE email = ?"
);
$stmt->bind_param("s", $email);
$stmt->execute();
$result = $stmt->get_result();
The original implementation directly inserted user-controlled data into a SQL statement. The corrected implementation uses a parameterized query so the supplied email value is treated as data rather than executable SQL syntax.
Other remediation changes followed the same principle: validate input at trust boundaries, encode untrusted output appropriately, enforce authorization server-side, protect state-changing requests, and minimize information exposed by the application.
My Improvements
The security improvements made to A Footballer's Delicacy included:
- Remediated unsafe SQL query patterns.
- Strengthened SQL injection protection.
- Improved XSS defenses.
- Added CSRF protection where required.
- Strengthened server-side input validation.
- Improved authentication and session security.
- Hardened session cookies.
- Improved authorization checks.
- Added/strengthened rate limiting for abuse-prone endpoints.
- Improved HTTP security headers.
- Added browser-side protections against clickjacking and MIME sniffing.
- Reduced unnecessary error information disclosure.
- Reviewed CORS configuration.
- Reviewed publicly accessible files and directories.
- Reduced unnecessary server/technology information disclosure.
- Reviewed sensitive endpoints and request handling.
- Tested security fixes against the affected application behavior.
- Verified that remediation did not break the existing website functionality.
The focus throughout the work was security remediation and reliability improvement in an existing codebase, not feature development.
Best Use of Sentry
Sentry was incorporated into the debugging and monitoring workflow to provide visibility into application errors and problematic execution paths.
Instead of relying exclusively on manual testing, Sentry helped provide additional observability into runtime behavior. This was useful when investigating errors, identifying affected application paths, and checking application stability after remediation.
The monitoring workflow focused on finding the underlying causes of errors rather than simply suppressing them.
After fixes were applied, Sentry could be used to monitor the affected paths for recurring exceptions and potential regressions.
Sentry evidence: [Add your actual Sentry issue/event/project link or screenshot here.]
Best Use of Google AI
Google AI was used as a development and security-analysis assistant during the remediation process.
It helped with:
- Reviewing existing application code.
- Identifying potentially unsafe coding patterns.
- Reasoning about possible vulnerability causes.
- Comparing remediation approaches.
- Reviewing edge cases.
- Suggesting security-focused test cases.
- Reviewing the final implementation for potential unintended effects.
AI suggestions were not treated as proof that a vulnerability existed or that a fix was correct. I manually reviewed the suggestions against the actual application, adapted the solutions to the existing codebase, and tested the resulting changes.
The final remediation was based on the combination of manual security testing, source-code analysis, Google AI assistance, application testing, and Sentry monitoring.
