CVE-2011-1067 in 389 Directory Server
Summary
by MITRE
slapd (aka ns-slapd) in 389 Directory Server before 1.2.8.a2 does not properly manage the c_timelimit field of the connection table element, which allows remote attackers to cause a denial of service (daemon outage) via Simple Paged Results connections, as demonstrated by using multiple processes to replay TCP sessions, a different vulnerability than CVE-2011-0019.
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Analysis
by VulDB Data Team • 03/17/2019
The vulnerability identified as CVE-2011-1067 affects the slapd daemon component of the 389 Directory Server, specifically targeting the management of the c_timelimit field within connection table elements. This flaw represents a critical denial of service vulnerability that can be exploited by remote attackers to disrupt directory services. The 389 Directory Server is a robust open-source implementation of the Lightweight Directory Access Protocol that serves as a centralized directory service for authentication and authorization in enterprise environments. The vulnerability specifically manifests when handling Simple Paged Results connections, which are used to retrieve large datasets from directory servers in manageable chunks. The c_timelimit field is crucial for controlling how long a connection can remain active during search operations, and improper management of this field creates exploitable conditions that can lead to daemon crashes and service outages.
The technical exploitation of this vulnerability involves leveraging multiple processes to replay TCP sessions, effectively creating a scenario where the connection table elements become corrupted or improperly managed due to the flawed handling of the c_timelimit field. This technique differs from other related vulnerabilities such as CVE-2011-0019, indicating a distinct attack vector that specifically targets the timing and connection management mechanisms within the slapd daemon. The flaw essentially allows attackers to manipulate the connection state management in a way that causes the daemon to enter an inconsistent state, leading to resource exhaustion or memory corruption that ultimately results in daemon termination. This type of vulnerability falls under the category of improper resource management as defined by CWE-400, where the system fails to properly handle resource lifecycle management, particularly in connection state tracking.
The operational impact of CVE-2011-1067 extends beyond simple service disruption to potentially compromise the availability of critical directory services within enterprise infrastructure. Directory servers serve as foundational components for authentication systems, single sign-on implementations, and various enterprise applications that depend on centralized identity management. When the slapd daemon becomes unresponsive or crashes due to this vulnerability, it can cause cascading failures throughout the organization's IT ecosystem, affecting user authentication, application access, and system integration processes. The vulnerability is particularly dangerous in environments where directory services are heavily utilized and where service availability is paramount for business operations. Organizations relying on 389 Directory Server versions prior to 1.2.8.a2 face significant risk of service interruptions that can last from minutes to hours, depending on the scale of the attack and the organization's recovery procedures.
Mitigation strategies for CVE-2011-1067 primarily involve upgrading to the patched version of the 389 Directory Server, specifically version 1.2.8.a2 or later, which addresses the improper management of the c_timelimit field in connection table elements. Network administrators should also implement monitoring solutions to detect unusual connection patterns or resource consumption spikes that may indicate exploitation attempts. Additionally, implementing connection rate limiting and session management controls can help reduce the impact of replay attacks by limiting the number of concurrent connections that can be established. The vulnerability demonstrates the importance of proper input validation and resource management in server applications, aligning with ATT&CK technique T1499.004 for resource exhaustion attacks. Organizations should also consider implementing network segmentation and access controls to limit the attack surface and reduce the potential for remote exploitation, particularly in environments where the directory service is exposed to untrusted networks. Regular security assessments and vulnerability scanning should be conducted to identify and remediate similar issues within the directory service infrastructure.