CVE-2002-0045 in OpenLDAP
Summary
by MITRE
slapd in OpenLDAP 2.0 through 2.0.19 allows local users, and anonymous users before 2.0.8, to conduct a "replace" action on access controls without any values, which causes OpenLDAP to delete non-mandatory attributes that would otherwise be protected by ACLs.
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Analysis
by VulDB Data Team • 04/30/2019
The vulnerability described in CVE-2002-0045 affects the slapd daemon in OpenLDAP versions 2.0 through 2.0.19, representing a significant access control flaw that undermines the security posture of directory services. This issue specifically targets the implementation of Access Control Lists (ACLs) within the Lightweight Directory Access Protocol (LDAP) server, creating a scenario where unauthorized attribute modifications can occur without proper authentication or authorization. The vulnerability manifests when users perform a "replace" operation on access controls without providing any values, which triggers an unexpected behavior in the directory service's attribute handling mechanism. This flaw particularly impacts systems where anonymous access was enabled before OpenLDAP version 2.0.8, creating an expanded attack surface for local users who could exploit this weakness to bypass normal security controls.
The technical implementation of this vulnerability stems from a flaw in how slapd processes attribute replacement operations when no values are provided during ACL modifications. When a user attempts to replace access control information without specifying replacement values, the system incorrectly interprets this as a deletion command for non-mandatory attributes that should normally be protected by ACLs. This behavior violates the fundamental principle of access control enforcement where proper authentication and authorization should be required before any attribute modifications can occur. The flaw essentially allows an attacker to bypass the normal ACL validation process, enabling them to remove or modify attributes that would typically remain protected. This represents a classic case of improper input validation and insufficient access control enforcement, aligning with CWE-284 which addresses improper access control issues. The vulnerability demonstrates how the absence of proper validation for empty attribute values can lead to privilege escalation and unauthorized data modification.
The operational impact of this vulnerability extends beyond simple attribute deletion, as it fundamentally compromises the integrity and confidentiality of directory services managed by OpenLDAP. Local users who can access the slapd service can exploit this weakness to remove critical attributes that protect sensitive information, potentially leading to data exposure or service disruption. Anonymous users with access to the LDAP service before version 2.0.8 could similarly exploit this flaw, creating a risk for organizations that maintained permissive access policies. The vulnerability undermines the trust model that directory services rely upon, as it allows attackers to modify the very access controls that protect the system's data. This weakness could enable attackers to escalate privileges, gain unauthorized access to protected information, or disrupt directory service operations. From an operational security standpoint, this vulnerability represents a critical weakness that could be leveraged in broader attack campaigns targeting directory services, particularly in environments where OpenLDAP serves as a core authentication and authorization infrastructure.
Organizations affected by CVE-2002-0045 should immediately implement mitigations including upgrading to OpenLDAP versions 2.0.20 or later where this vulnerability has been addressed, disabling anonymous access where possible, and implementing additional access controls to limit local user privileges. The vulnerability also highlights the importance of proper input validation and access control enforcement mechanisms within directory services, aligning with ATT&CK technique T1078 which covers valid accounts and privilege escalation. System administrators should conduct comprehensive audits of their LDAP configurations to identify and remediate similar vulnerabilities in access control implementations. Additionally, organizations should consider implementing monitoring solutions that can detect anomalous attribute modification patterns, as this vulnerability could be used to silently modify directory information without triggering typical security alerts. The remediation process should include not only patching the software but also reviewing and strengthening overall directory service security policies to prevent similar issues from arising in other components of the authentication infrastructure.