CVE-2012-1164 in OpenLDAP
Summary
by MITRE
slapd in OpenLDAP before 2.4.30 allows remote attackers to cause a denial of service (assertion failure and daemon exit) via an LDAP search query with attrsOnly set to true, which causes empty attributes to be returned.
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Analysis
by VulDB Data Team • 03/22/2021
The vulnerability described in CVE-2012-1164 affects the slapd daemon in OpenLDAP versions prior to 2.4.30, representing a critical denial of service weakness that can be exploited by remote attackers to disrupt LDAP services. This vulnerability specifically targets the handling of LDAP search queries when the attrsOnly parameter is set to true, creating a scenario where the daemon encounters an assertion failure that results in its premature termination. The flaw exists within the core directory service implementation that processes search operations, making it a fundamental security issue that impacts the availability of directory services across numerous enterprise environments relying on OpenLDAP.
The technical mechanism behind this vulnerability involves the improper handling of empty attribute responses when processing LDAP search operations with specific parameters. When an attacker crafts a search query with attrsOnly set to true, the slapd daemon attempts to process the request and encounters a condition where empty attributes are returned as part of the search results. This particular scenario triggers an assertion failure within the daemon's code execution flow, causing the process to terminate unexpectedly. The assertion failure occurs because the code does not properly validate or handle the edge case where attributes are empty while maintaining the attrsOnly flag, which is a standard LDAP search parameter used to retrieve only attribute names without their values.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be leveraged by attackers to systematically degrade directory services availability. Organizations utilizing OpenLDAP servers without the applicable patch may experience intermittent service outages or complete daemon failures, potentially affecting authentication, authorization, and directory lookup services that depend on these systems. The vulnerability is particularly concerning because it requires minimal effort to exploit, as attackers only need to construct a specific LDAP search query with the attrsOnly parameter set to true. This makes it an attractive target for automated attacks or malicious actors seeking to disrupt critical infrastructure services that rely on LDAP directory services for identity management and access control.
Mitigation strategies for this vulnerability should focus on immediate patch application to OpenLDAP versions 2.4.30 and later, which contain the necessary code modifications to properly handle the edge case involving empty attributes with the attrsOnly parameter. System administrators should also implement monitoring solutions to detect unusual patterns in LDAP search operations that might indicate exploitation attempts, particularly those involving the attrsOnly parameter. Additionally, network-level controls such as firewalls and access control lists can be configured to limit LDAP service access to trusted sources only, reducing the attack surface. From a compliance perspective, this vulnerability aligns with CWE-617, which addresses reachable assertions, and can be mapped to ATT&CK technique T1499.004 for network denial of service, highlighting the need for both defensive measures and continuous monitoring to prevent exploitation of this fundamental service availability flaw.