Sql Injection in Aspnet with Basic Auth

SQL injection in ASP.NET applications using HTTP Basic Authentication can occur when credentials are accepted as user input and then incorporated into SQL queries without proper validation or parameterization. Even though Basic Authentication credentials are typically transmitted via the Authorization header, developers sometimes parse these credentials and use them directly in database operations, such as looking up user roles or permissions.

For example, consider an endpoint that receives a username and password from the Authorization header, then builds a dynamic SQL string to fetch user data:

// UNSAFE: string concatenation with user input
string username = ExtractUsernameFromHeader(Request.Headers["Authorization"]);
string query = "SELECT * FROM Users WHERE Username = '" + username + "'";
using var cmd = new SqlCommand(query, connection);

If an attacker sends a crafted Authorization header such as admin' OR '1'='1, the resulting SQL query becomes:

SELECT * FROM Users WHERE Username = 'admin' OR '1'='1'

This can bypass authentication logic and potentially grant access to other data. The risk is compounded when the application also constructs dynamic queries for data access based on the authenticated identity. Injection can lead to unauthorized data reading, data modification, or account bypass. This pattern violates the principle of least privilege and fails to treat user input as untrusted, even when the input originates from an authentication header.

OWASP API Top 10 category API1:2023 Broken Object Level Authorization (BOLA)/IDOR is often relevant when object-level access is inferred from the authenticated identity without additional checks. For instance, after extracting a user identifier from SQL, an attacker might manipulate that identifier to access other users’ resources. Input Validation and Authentication checks in middleBrick scans are designed to detect such risky query construction and missing parameterization.

To mitigate SQL injection when using Basic Authentication in ASP.NET, always treat credentials as untrusted input and use parameterized queries or an ORM with built-in protections. Avoid string concatenation or interpolation when forming SQL commands.

Secure approach using parameterized queries:

// SECURE: parameterized query
string username = ExtractUsernameFromHeader(Request.Headers["Authorization"]);
string query = "SELECT * FROM Users WHERE Username = @Username";
using var cmd = new SqlCommand(query, connection);
cmd.Parameters.AddWithValue("@Username", username);
using var reader = cmd.ExecuteReader();

If you use an ORM like Entity Framework, bind parameters through the model rather than raw SQL:

// Using Entity Framework with parameterized query semantics
var user = dbContext.Users
    .Where(u => u.Username == username)
    .FirstOrDefault();

Additional remediation steps include:

• Validate the format of the username (e.g., allow only alphanumeric characters where appropriate) before using it in any query.
• Use HTTPS to protect credentials in transit, as Basic Authentication sends base64-encoded credentials that are easily decoded without encryption.
• Apply the principle of least privilege to the database account used by the application, restricting permissions to only what is necessary.
• Leverage middleBrick’s Authentication and Input Validation checks to automatically identify dynamic query construction and missing parameterization in your API endpoints.

For continuous assurance, the middleBrick CLI can be integrated into scripts or the GitHub Action to fail builds when insecure patterns are detected. The dashboard allows tracking of these findings over time, while the Pro plan provides ongoing monitoring of your APIs.