Generic LDAP Injection Vulnerability Scanner

LDAP is a protocol used to access and manage directory information (such as user accounts, groups, and resource records) across networks. Directory services that implement LDAP are commonly used by enterprises, identity providers, single-sign-on systems, and many applications that delegate authentication or store user metadata. These systems are typically deployed by IT teams, application developers, and system integrators to centralize identity and access management, enable group policy enforcement, and support authentication flows. Because LDAP servers often contain sensitive account and configuration data, insecure handling of LDAP input in applications can expose significant risks. Scanners for LDAP injection are used by security teams and automated tools to find unsanitized LDAP query usage in web forms, APIs, and backend services. Regular scanning helps organizations reduce attack surface, meet compliance requirements, and prevent data leakage from directory services.

LDAP injection occurs when an application constructs LDAP queries by concatenating or interpolating untrusted input directly into an LDAP filter or DN (distinguished name) without proper validation or escaping. Attackers can craft specially formed input that changes the structure of the LDAP query, allowing broader search results, bypassing authentication checks, or exposing sensitive directory entries. Common injection vectors include login forms, search fields, user-lookup APIs, and any functionality that accepts usernames, group names, or filter components. The vulnerability typically arises from improper input sanitization, absence of parameterized query APIs, or reliance on string concatenation to build LDAP filters. Exploitation can be automated and chained with other issues (e.g., weak credentials or misconfigured ACLs) to escalate impact. Detecting these injection points enables remediation before attackers harvest credentials or pivot into internal systems.

Technically, LDAP injection targets endpoints that accept user input to build LDAP filters such as (uid={input}), (cn={input}), or DN constructions like uid={input},ou=users,dc=example,dc=com. A vulnerable parameter is any form field, header, or API parameter incorporated into the filter without escaping special LDAP filter meta-characters (e.g., '*', '(', ')', '\\', NUL). Attackers can inject filter operators (|, &) and wildcards to broaden searches, or use crafted sequences to close and append clauses that alter query logic. The scanner examines responses and behavior for differences when sending benign vs. crafted malicious payloads that attempt to manipulate the filter. Detection techniques include timing, boolean-based checks, response content differences, and LDAP error messages that reveal query parsing behavior. Effective scanners also test common payloads that bypass naive escapes and verify results against control queries.

If exploited, LDAP injection can lead to unauthorized disclosure of user lists, attribute values (email, phone, group membership), authentication bypass (e.g., finding accounts that match broad filters), and facilitation of lateral movement by revealing account names to target for password attacks. In systems where LDAP is used to authorize actions, attackers may manipulate group membership checks to gain access to privileged functionality. Combined with weak access controls or misconfigured directory permissions, an attacker could exfiltrate sensitive configuration or credential material stored in the directory. Even when direct data access is limited, information gathered via LDAP injection can be used to craft high-quality social engineering or account takeover attacks. The presence of LDAP injection increases the overall risk of identity compromise and impacts confidentiality and authorization guarantees.

REFERENCES

• https://owasp.org/www-project-top-ten/2017/A1_2017-Injection.html
• https://owasp.org/www-community/attacks/LDAP_Injection