CVE-2018-1089 in 389-ds-base
Summary
by MITRE
389-ds-base before versions 1.4.0.9, 1.3.8.1, 1.3.6.15 did not properly handle long search filters with characters needing escapes, possibly leading to buffer overflows. A remote, unauthenticated attacker could potentially use this flaw to make ns-slapd crash via a specially crafted LDAP request, thus resulting in denial of service.
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Analysis
by VulDB Data Team • 03/11/2023
The vulnerability identified as CVE-2018-1089 affects the 389 Directory Server base component, specifically versions prior to 1.4.0.9, 1.3.8.1, and 1.3.6.15. This issue resides within the LDAP search filter processing functionality of the directory service daemon, which is a critical component for enterprise identity management and authentication systems. The 389 Directory Server serves as a robust open-source implementation of the Lightweight Directory Access Protocol and is widely deployed in enterprise environments for managing user identities, access control, and directory services across complex organizational infrastructures.
The technical flaw manifests when the ns-slapd daemon processes LDAP search filters containing long sequences of characters that require escaping operations. During the parsing and processing of these malformed search filters, the software fails to properly validate buffer boundaries, leading to potential buffer overflow conditions. This occurs because the implementation does not adequately account for the expansion that occurs when special characters are escaped during filter processing, causing memory allocation to exceed intended buffer limits. The vulnerability specifically targets the filter parsing routine within the LDAP processing pipeline, which is fundamental to how directory queries are executed and interpreted by the server.
The operational impact of this vulnerability is significant as it enables remote, unauthenticated attackers to trigger denial of service conditions against affected 389 Directory Server instances. An attacker can construct a specially crafted LDAP request containing an excessively long search filter with escape sequences that will cause the ns-slapd process to crash upon processing. This results in complete service disruption for directory services, affecting authentication, authorization, and directory lookup operations that countless applications and systems depend upon. The vulnerability is particularly dangerous in enterprise environments where directory services are central to identity management, as it can lead to cascading failures affecting multiple dependent systems and potentially compromising overall network security posture.
Mitigation strategies should prioritize immediate patching of affected 389 Directory Server installations to versions 1.4.0.9, 1.3.8.1, or 1.3.6.15, which contain the necessary fixes for proper buffer handling and escape sequence processing. Network administrators should also implement monitoring and intrusion detection systems to identify suspicious LDAP traffic patterns that may indicate exploitation attempts. Additionally, implementing rate limiting and request size restrictions on LDAP services can help reduce the impact of potential attacks while patches are being deployed. This vulnerability aligns with CWE-121, Buffer Overflow in Stack, and represents a classic example of improper input validation in network services, making it relevant to ATT&CK technique T1499.004 for network denial of service attacks. Organizations should also consider implementing network segmentation and access controls to limit exposure of directory services to untrusted networks, reducing the attack surface for such vulnerabilities.