CVE-2006-0647 in Java System Directory Server
Summary
by MITRE
LDAP service in Sun Java System Directory Server 5.2, running on Linux and possibly other platforms, allows remote attackers to cause a denial of service (memory allocation error) via an LDAP packet with a crafted subtree search request, as demonstrated using the ProtoVer LDAP test suite.
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Analysis
by VulDB Data Team • 04/26/2025
The vulnerability identified as CVE-2006-0647 represents a critical denial of service flaw within the LDAP service implementation of Sun Java System Directory Server version 5.2. This issue affects systems running on Linux platforms and potentially other operating systems where the directory server is deployed. The vulnerability stems from insufficient input validation mechanisms within the LDAP processing pipeline, specifically when handling subtree search requests. The flaw manifests when the server receives a malformed LDAP packet containing a crafted subtree search request that triggers improper memory allocation handling within the directory service daemon.
The technical exploitation of this vulnerability occurs through the manipulation of LDAP protocol messages, specifically targeting the subtree search functionality that is commonly used in directory service operations. When the Sun Java System Directory Server processes a specially crafted LDAP packet, the server's memory management subsystem fails to properly handle the malformed request, leading to memory allocation errors that ultimately result in service termination. This type of vulnerability falls under the CWE-122 category of "Heap-based Buffer Overflow" as it involves improper handling of memory allocation during processing of malformed input data. The attack vector is particularly concerning as it requires only network access to the LDAP service port, making it remotely exploitable without authentication requirements.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be leveraged to create persistent availability issues within directory services that many enterprise applications depend upon. Directory servers form the backbone of identity management and authentication infrastructure in large organizations, making this denial of service attack potentially devastating to business operations. When the LDAP service becomes unresponsive due to memory allocation errors, it affects all applications and systems that rely on directory lookups for user authentication, authorization, and access control decisions. The vulnerability's exploitation can be automated and does not require specialized knowledge of the underlying system architecture, making it particularly dangerous in production environments.
Mitigation strategies for this vulnerability should focus on immediate patch application from Oracle, as the vendor released security updates specifically addressing this memory allocation flaw in subsequent versions of the Sun Java System Directory Server. Organizations should implement network segmentation and access controls to limit exposure of LDAP service ports to trusted networks only, while monitoring for unusual LDAP traffic patterns that might indicate exploitation attempts. The implementation of intrusion detection systems capable of identifying malformed LDAP packets can provide early warning of potential attacks. Additionally, configuring the directory server with appropriate resource limits and memory constraints can help prevent complete service exhaustion, though this approach does not address the root cause. From an ATT&CK framework perspective, this vulnerability maps to the T1499.004 technique of "Network Denial of Service" and represents a classic example of how protocol-level flaws can be exploited to achieve system availability compromise without direct system access.