LDAP (Lightweight Directory Access Protocol) Injection is a type of security vulnerability that occurs when untrusted data is inserted into LDAP queries without proper validation or sanitization. Attackers exploit this vulnerability to manipulate LDAP queries and potentially gain unauthorized access to sensitive information or perform malicious actions on the directory server.
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LDAP Queries: LDAP is a protocol used for accessing and managing directory services, such as user authentication and authorization.
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User Input: Applications often construct LDAP queries dynamically based on user-supplied input, such as usernames, passwords, or search criteria.
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Injection: Attackers input malicious LDAP filter strings or payloads into input fields or parameters, hoping to manipulate the structure or logic of the LDAP query.
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Execution: When the application constructs and executes the LDAP query without proper validation, the injected malicious code can alter the query's behavior, leading to unauthorized access or disclosure of sensitive information.
Suppose a web application uses LDAP to authenticate users against a directory server. The application constructs an LDAP query based on the user-supplied username and password. If an attacker enters a malicious payload like )(cn=))(|(password=*), it could modify the LDAP query to return all user records, bypassing authentication and potentially disclosing sensitive information.
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Unauthorized Access: Attackers can manipulate LDAP queries to bypass authentication mechanisms, gain unauthorized access to user accounts, or escalate privileges within the directory server.
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Information Disclosure: LDAP Injection vulnerabilities can expose sensitive information stored in the directory server, such as user credentials, organizational data, or system configurations.
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Data Manipulation: Attackers may modify LDAP queries to alter or delete directory entries, manipulate user attributes, or perform other unauthorized actions on the directory server.
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Input Validation: Validate and sanitize user input before constructing LDAP queries to ensure that it adheres to expected formats and does not contain malicious characters or payloads.
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Parameterized Queries: Use parameterized LDAP queries or prepared statements to separate data from query logic, preventing LDAP Injection vulnerabilities.
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Least Privilege Principle: Limit the privileges of LDAP authentication and authorization components to minimize the impact of successful LDAP Injection attacks.
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Input Encoding: Encode user input before incorporating it into LDAP queries to prevent special characters or LDAP metacharacters from being interpreted as part of the query syntax.
LDAP Injection is a critical security vulnerability that can lead to unauthorized access, information disclosure, and data manipulation within directory services. By understanding how LDAP Injection works and implementing appropriate security measures such as input validation, parameterized queries, and least privilege principles, developers can mitigate the risk of exploitation and protect their directory servers from malicious attacks. Regular security assessments and updates are essential for maintaining a secure LDAP environment.