CVE-2011-1081 in OpenLDAP
Summary
by MITRE
modrdn.c in slapd in OpenLDAP 2.4.x before 2.4.24 allows remote attackers to cause a denial of service (daemon crash) via a relative Distinguished Name (DN) modification request (aka MODRDN operation) that contains an empty value for the OldDN field.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 08/18/2024
The vulnerability described in CVE-2011-1081 represents a critical denial of service flaw within the OpenLDAP directory service implementation. This issue specifically affects the slapd daemon's handling of MODRDN operations, which are used to rename or move directory entries within the LDAP directory structure. The vulnerability stems from insufficient input validation in the modrdn.c component of OpenLDAP's server implementation, creating a condition where malformed DN modification requests can trigger unexpected behavior in the directory service daemon.
The technical flaw manifests when a remote attacker crafts a MODRDN operation request with an empty value in the OldDN field of the distinguished name modification. This particular input validation failure creates a scenario where the slapd daemon fails to properly handle the malformed request, leading to an abrupt crash of the directory service. The vulnerability exists in OpenLDAP versions 2.4.x prior to 2.4.24, indicating that this was a relatively widespread issue affecting a significant portion of the OpenLDAP user base during that period. The flaw operates at the protocol level, making it particularly dangerous as it can be exploited through standard LDAP network communication without requiring special privileges or authentication.
The operational impact of this vulnerability extends beyond simple service disruption, as it can severely compromise directory service availability within organizations relying on OpenLDAP for critical infrastructure components. Directory services form the backbone of many enterprise authentication and authorization systems, making denial of service attacks particularly damaging. When the slapd daemon crashes due to this vulnerability, it results in complete unavailability of the LDAP directory service until manual intervention and service restart occur. This can cascade into broader system failures as applications and services depending on directory lookups become unable to function properly, potentially affecting user authentication, access control, and other directory-dependent operations across the enterprise.
The vulnerability aligns with CWE-121, which describes buffer overflow conditions, and represents a classic example of improper input validation leading to service disruption. From an ATT&CK framework perspective, this vulnerability maps to the T1499.004 technique for network denial of service, where adversaries exploit weaknesses in network infrastructure services to disrupt availability. Organizations should implement immediate mitigation strategies including applying the available patches for OpenLDAP 2.4.24 and later versions, implementing network-level access controls to restrict LDAP service exposure, and deploying monitoring solutions to detect unusual MODRDN operations. Additionally, organizations should consider implementing redundant directory services and establishing incident response procedures specifically addressing directory service outages to minimize business impact when such vulnerabilities are exploited.