CVE-2012-2134 in bind-dyndb-ldap
Summary
by MITRE
The handle_connection_error function in ldap_helper.c in bind-dyndb-ldap before 1.1.0rc1 does not properly handle LDAP query errors, which allows remote attackers to cause a denial of service (infinite loop and named server hang) via a non-alphabet character in the base DN in an LDAP search DNS query.
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Analysis
by VulDB Data Team • 04/12/2025
The vulnerability identified as CVE-2012-2134 resides within the bind-dyndb-ldap plugin version 1.1.0rc1 and earlier, specifically in the ldap_helper.c file where the handle_connection_error function fails to adequately process LDAP query errors. This flaw manifests when processing DNS queries that contain non-alphabet characters within the base DN component of an LDAP search operation, creating a critical security weakness that can be exploited by remote attackers to execute denial of service attacks against DNS servers utilizing this plugin.
The technical implementation of this vulnerability stems from insufficient error handling mechanisms within the LDAP connection management code. When a DNS query containing non-alphabet characters in the base DN is processed, the handle_connection_error function enters an infinite loop state rather than properly terminating the connection attempt or returning appropriate error codes. This condition causes the named server process to hang indefinitely, effectively rendering the DNS service unavailable to legitimate clients while maintaining the appearance of normal operation to monitoring systems. The flaw operates at the intersection of LDAP protocol handling and DNS server functionality, creating a scenario where malformed input triggers a state machine failure rather than graceful error recovery.
The operational impact of this vulnerability extends beyond simple service disruption to encompass broader system reliability concerns within DNS infrastructure deployments. Remote attackers can exploit this weakness by crafting malicious DNS queries that contain special characters, numbers, or other non-alphabetic elements in the base DN portion of LDAP search operations. The resulting infinite loop consumes system resources and prevents the named server from processing legitimate queries, potentially leading to cascading failures in DNS resolution across affected networks. This vulnerability particularly affects DNS servers configured with dynamic DNS updates through LDAP integration, making it a significant concern for organizations relying on bind-dyndb-ldap for dynamic zone management.
Mitigation strategies for CVE-2012-2134 involve immediate deployment of the patched version 1.1.0rc1 or later of bind-dyndb-ldap, which implements proper error handling for LDAP query failures. Organizations should also consider implementing network-level filtering to restrict incoming DNS queries containing suspicious character patterns in base DN components, though this approach provides only partial protection. The vulnerability aligns with CWE-362, which addresses concurrent execution issues and improper error handling in system operations, and maps to ATT&CK technique T1499.004 for network denial of service attacks. System administrators should also monitor for unusual resource consumption patterns and implement automated restart mechanisms for named processes to minimize service disruption during exploitation attempts. Additionally, regular security audits of DNS server configurations and LDAP integration components should be conducted to identify similar error handling weaknesses that could lead to comparable denial of service conditions.