CVE-2011-0019 in Directory Server
Summary
by MITRE
slapd (aka ns-slapd) in 389 Directory Server 1.2.7.5 (aka Red Hat Directory Server 8.2.x or dirsrv) does not properly handle simple paged result searches, which allows remote attackers to cause a denial of service (daemon crash) or possibly have unspecified other impact via multiple search requests.
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Analysis
by VulDB Data Team • 04/24/2017
The vulnerability identified as CVE-2011-0019 affects the slapd daemon component of the 389 Directory Server version 1.2.7.5, which is also known as Red Hat Directory Server 8.2.x or dirsrv. This critical flaw resides within the directory server's implementation of simple paged result searches, a standard LDAP functionality designed to handle large result sets by breaking them into manageable pages. The issue manifests when the server processes multiple search requests that utilize this paging mechanism, creating a scenario where the daemon becomes unstable and potentially crashes.
The technical implementation flaw stems from inadequate input validation and memory management within the slapd process when handling paged search operations. When attackers submit multiple search requests that manipulate the page size parameters and pagination controls, the server's internal state becomes corrupted, leading to memory corruption or resource exhaustion. This vulnerability operates at the protocol level, specifically targeting the LDAP search operation implementation, and can be exploited remotely without requiring authentication. The flaw falls under the category of improper handling of input data as classified by CWE-248, which encompasses issues where programs fail to properly handle exceptional conditions or malformed input.
The operational impact of this vulnerability extends beyond simple denial of service, as the daemon crash can result in complete service unavailability for directory services, affecting authentication, authorization, and directory lookup functions across systems relying on the affected directory server. Organizations utilizing this version of the directory server face significant risk of service disruption, particularly in environments where directory services are critical for user authentication and access control. The unspecified other impacts mentioned in the vulnerability description suggest potential for more severe consequences including privilege escalation or information disclosure, though these remain unconfirmed. This vulnerability directly aligns with ATT&CK technique T1499.004 for Denial of Service and could potentially map to T1566.001 for credential access through service exploitation.
Mitigation strategies should prioritize immediate deployment of vendor patches and updates, as Red Hat and 389 Directory Server maintainers have released fixes addressing this specific memory handling issue. Organizations should implement network segmentation to limit exposure of directory servers to untrusted networks and consider implementing rate limiting on search operations to prevent abuse of the paged search functionality. Monitoring for unusual search patterns and implementing intrusion detection systems can help identify exploitation attempts. Additionally, system administrators should regularly update their directory server implementations and maintain current security patches to protect against similar vulnerabilities in the LDAP protocol implementation. The vulnerability demonstrates the importance of robust input validation in network services and highlights the need for comprehensive testing of protocol implementations under stress conditions to prevent memory corruption exploits.