Here’s a comprehensive explanation of the LDAP Injection attack, a serious security vulnerability that can compromise directory services like Active Directory:

🧬 What Is LDAP Injection?

LDAP Injection is a type of attack where malicious input is inserted into an LDAP (Lightweight Directory Access Protocol) query. It exploits applications that fail to properly sanitize user input, allowing attackers to manipulate LDAP statements and gain unauthorized access to sensitive data or functionality.

🧠 How LDAP Injection Works

LDAP queries are used to search and manage directory entries (like usernames, emails, roles). A typical query might look like:

(&(uid=alice)(password=secret))

If an application directly inserts user input into this query without validation, an attacker could input something like:

alice)(|(uid=*))  // This bypasses authentication

Resulting in:

(&(uid=alice)(|(uid=*))(password=...))

This query matches any user, effectively bypassing login controls.

🚨 Potential Impacts

• Authentication bypass: Log in without valid credentials.
• Privilege escalation: Modify access rights or roles.
• Information disclosure: Extract sensitive data like emails, passwords, or organizational structure.
• Data manipulation: Alter or delete LDAP entries.

🛡️ How to Prevent LDAP Injection

• Sanitize all user inputs: Use strict input validation and escaping.
• Avoid string concatenation: Use parameterized queries or safe APIs.
• Implement access controls: Restrict what users can query or modify.
• Use secure authentication mechanisms: Avoid relying solely on LDAP filters for login logic.
• Perform security testing: Use tools like Dynamic Application Security Testing (DAST) to detect vulnerabilities.

🔍 Real-World Relevance

LDAP Injection is similar to SQL Injection but targets directory services. It’s especially dangerous in environments using Active Directory, OpenLDAP, or ADAM, where directory data governs access to critical systems.