CVE-2016-4992 in Enterprise Linux Desktop
Summary
by MITRE
389 Directory Server in Red Hat Enterprise Linux Desktop 6 through 7, Red Hat Enterprise Linux HPC Node 6 through 7, Red Hat Enterprise Linux Server 6 through 7, and Red Hat Enterprise Linux Workstation 6 through 7 allows remote attackers to infer the existence of RDN component objects.
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Analysis
by VulDB Data Team • 12/08/2022
The vulnerability identified as CVE-2016-4992 affects the 389 Directory Server implementation across multiple Red Hat Enterprise Linux versions, presenting a significant information disclosure risk. This directory service operates as a core component in enterprise environments for managing user identities, access controls, and organizational data structures. The flaw manifests in how the server handles requests for Relative Distinguished Name (RDN) component objects, which are fundamental elements in LDAP directory structures that define object hierarchies and relationships within the directory tree.
The technical nature of this vulnerability stems from the server's response behavior when processing queries for non-existent RDN components. Specifically, the 389 Directory Server provides different response patterns or error messages when attempting to access objects that do not exist versus those that exist but are inaccessible due to permission restrictions. This differential response allows remote attackers to perform inference attacks, essentially enabling them to determine whether specific directory objects exist within the server's database without requiring authentication or explicit access rights. The vulnerability operates at the protocol level, leveraging the server's information disclosure characteristics during LDAP bind and search operations.
The operational impact of CVE-2016-4992 extends beyond simple information gathering, as it provides attackers with valuable reconnaissance data about the directory structure and object composition. This intelligence can significantly aid in planning more sophisticated attacks, such as privilege escalation attempts, targeted credential harvesting, or mapping of organizational relationships within the directory environment. The vulnerability is particularly concerning in enterprise settings where directory servers contain sensitive organizational data, user credentials, and access control information. Attackers can use this information to build detailed maps of the directory structure, identify potential targets for further exploitation, and understand the overall organization of the directory service. This type of information disclosure aligns with CWE-200, which categorizes weaknesses related to information exposure, and represents a classic example of how seemingly benign server responses can leak critical structural information.
Mitigation strategies for this vulnerability require immediate patching of affected 389 Directory Server installations, as Red Hat has released security updates addressing this specific issue. Organizations should also implement network segmentation and access controls to limit exposure of directory services to untrusted networks. Additional protective measures include configuring proper firewall rules to restrict LDAP traffic to authorized systems, implementing intrusion detection systems to monitor for unusual directory access patterns, and conducting regular security assessments of directory services. The ATT&CK framework categorizes this vulnerability under reconnaissance techniques, specifically information gathering, where attackers use server response differences to extract organizational intelligence. Organizations should also consider implementing directory service monitoring solutions that can detect anomalous query patterns and potential inference attacks, as the vulnerability represents a passive reconnaissance method that may not trigger traditional security alerts.