CVE-2000-1045 in nss_ldap
Summary
by MITRE
nss_ldap earlier than 121, when run with nscd (name service caching daemon), allows remote attackers to cause a denial of service via a flood of LDAP requests.
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Analysis
by VulDB Data Team • 05/22/2017
The vulnerability described in CVE-2000-1045 represents a significant security weakness in the nss_ldap library version 121 and earlier, specifically when integrated with the nscd name service caching daemon. This issue manifests as a denial of service condition that can be triggered by remote attackers through the systematic flooding of LDAP requests. The nss_ldap library serves as a critical component in Linux and Unix systems by enabling name service resolution through Lightweight Directory Access Protocol, while nscd acts as a caching daemon to improve performance by storing frequently accessed name service information. When these two components operate in conjunction, they create a potential attack vector that adversaries can exploit to disrupt system availability.
The technical flaw underlying this vulnerability stems from insufficient request handling and resource management within the nss_ldap implementation when interfaced with nscd. The flaw occurs because the library fails to properly rate-limit or throttle incoming LDAP requests, allowing malicious actors to overwhelm the system with excessive connection attempts or query volumes. This lack of proper request validation and resource allocation creates a condition where legitimate system resources become consumed by the flood of requests, leading to service degradation or complete unavailability. The vulnerability specifically affects systems where nss_ldap is configured to use nscd as a caching mechanism, making it particularly relevant in enterprise environments that rely on LDAP for user authentication and directory services.
The operational impact of this vulnerability extends beyond simple service disruption, potentially affecting critical infrastructure components that depend on name resolution services. Attackers can leverage this weakness to launch denial of service attacks against systems that utilize LDAP-based authentication, leading to cascading failures in network services, user authentication systems, and potentially business-critical applications that depend on directory services. The vulnerability is particularly concerning because it operates at the system level where name resolution is fundamental to network operations, making it difficult to isolate and mitigate without affecting core system functionality. Organizations relying on LDAP integration for user management and authentication face significant risk of operational disruption and potential service outages.
Mitigation strategies for CVE-2000-1045 should prioritize immediate patching of affected nss_ldap versions to 121 or later, where the vulnerability has been addressed through improved request handling and resource management. System administrators should implement network-level controls such as firewall rules and rate limiting to restrict LDAP traffic from suspicious sources, while also configuring nscd to implement appropriate connection limits and timeouts. Additionally, monitoring systems should be deployed to detect unusual patterns of LDAP requests that could indicate an ongoing attack, enabling rapid response to potential exploitation attempts. This vulnerability aligns with CWE-400, which categorizes issues related to resource exhaustion, and represents a classic example of how improper input validation can lead to denial of service conditions. The attack pattern follows ATT&CK technique T1499.004, which focuses on network denial of service attacks, highlighting the importance of implementing proper rate limiting and resource management controls to prevent exploitation.