Unauthenticated SQL Injection in Login Endpoint

Security Assessment – Critical SQL Injection in Authentication Endpoint

During a private security assessment of a live web application (name withheld for confidentiality), I identified a critical SQL Injection vulnerability affecting the user authentication mechanism.

The issue was located in the login form, where user input was improperly handled and directly embedded into a SQL query without adequate sanitization. This allowed an attacker to craft a malicious payload and bypass the login process entirely.

? Technical Summary:

Vulnerability Type: Unauthenticated SQL Injection (Login Bypass)

Location: POST /login endpoint

Payload Used: ' OR '1'='1

Impact: Full authentication bypass without valid credentials

? Proof of Concept:

Access the login page of the application.

Submit ' OR '1'='1 as the username.

Use any password or leave it blank.

Upon submission, the application grants access to an authenticated session.

️ Security Impact:

This vulnerability posed a severe risk, potentially allowing unauthorized access to administrative accounts, exposure of sensitive user data, and full compromise of backend functionality.

Remediation Recommendation:

Replace raw SQL queries with parameterized queries or prepared statements.

Sanitize and validate all user inputs server-side.

Implement robust authentication and session handling mechanisms.

Apply the principle of least privilege to database accounts.

The vulnerability was responsibly disclosed to the appropriate party and resolved in a timely manner.