CVE-2011-0704 in 389 Directory Server
Summary
by MITRE
389 Directory Server 1.2.7.5, when built with mozldap, allows remote attackers to cause a denial of service (replica crash) by sending an empty modify request.
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Analysis
by VulDB Data Team • 02/02/2020
The CVE-2011-0704 vulnerability affects the 389 Directory Server version 1.2.7.5 when compiled with the mozldap library, presenting a significant denial of service risk that can lead to replica crashes. This vulnerability stems from insufficient input validation within the directory server's modify operation handling mechanism, specifically when processing empty modify requests from remote attackers. The flaw represents a classic buffer overflow condition that occurs during the parsing of malformed LDAP modify operations, where the server fails to properly validate the structure and content of incoming requests before attempting to process them.
The technical implementation of this vulnerability exploits the server's inadequate handling of empty modify operations within the LDAP protocol stack. When a remote attacker sends a specially crafted empty modify request, the 389 Directory Server's mozldap component fails to validate the request parameters properly, leading to memory corruption that ultimately results in the server replica crashing. This behavior aligns with CWE-121, which describes heap-based buffer overflow conditions, and specifically relates to improper input validation in network protocol handling. The vulnerability exists because the server's input sanitization routines do not adequately check for empty or malformed modify operations before proceeding with internal processing.
The operational impact of CVE-2011-0704 extends beyond simple service disruption, as it can compromise the integrity of directory services in enterprise environments. When a replica crashes, it can lead to cascading failures in directory replication, potentially causing authentication failures across multiple systems that depend on the directory service. This vulnerability is particularly dangerous in environments where 389 Directory Server serves as a critical component for user authentication, access control, and identity management. The remote nature of the attack means that adversaries can exploit this vulnerability from anywhere on the network without requiring local system access or credentials, making it a high-severity threat that can be leveraged for both disruption and potential reconnaissance purposes.
Mitigation strategies for this vulnerability should include immediate patching of the 389 Directory Server to version 1.2.7.6 or later, which contains the necessary fixes for the empty modify request handling. Organizations should also implement network-level controls such as firewall rules that restrict LDAP traffic to trusted sources only, and deploy intrusion detection systems that can monitor for suspicious LDAP modify operations. Additionally, administrators should consider implementing request rate limiting and connection throttling mechanisms to prevent abuse of the vulnerable functionality. From an operational security perspective, regular vulnerability assessments and penetration testing should be conducted to identify similar issues in other directory services and LDAP implementations. The vulnerability also highlights the importance of proper input validation in network services and aligns with ATT&CK technique T1499.001, which covers network denial of service attacks, emphasizing the need for robust protocol handling and validation mechanisms in enterprise directory services.