CVE-2012-3868 in BIND
Summary
by MITRE
Race condition in the ns_client structure management in ISC BIND 9.9.x before 9.9.1-P2 allows remote attackers to cause a denial of service (memory consumption or process exit) via a large volume of TCP queries.
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Analysis
by VulDB Data Team • 03/27/2021
The vulnerability identified as CVE-2012-3868 represents a critical race condition within the ns_client structure management component of ISC BIND version 9.9.x prior to 9.9.1-P2. This flaw specifically targets the handling of TCP queries in the Domain Name System server implementation, creating a scenario where remote attackers can exploit temporal inconsistencies in memory management to disrupt service availability. The race condition manifests when multiple concurrent TCP query requests are processed simultaneously, leading to improper synchronization of client structure allocations and deallocations within the server's memory space.
The technical exploitation of this vulnerability occurs through the manipulation of TCP query volumes, where attackers can flood the DNS server with a large number of concurrent TCP connections that trigger the race condition in ns_client structure handling. When the server processes these queries, the improper synchronization causes memory allocation failures or process termination events that result in denial of service conditions. The flaw stems from inadequate thread synchronization mechanisms when managing client connections and their associated memory structures, allowing concurrent access to shared resources without proper locking protocols. This vulnerability directly maps to CWE-362, which describes race conditions in concurrent programming where multiple threads or processes access shared data simultaneously, leading to unpredictable behavior and system instability.
The operational impact of CVE-2012-3868 extends beyond simple service disruption to potentially compromise the entire DNS infrastructure that relies on ISC BIND servers. When exploited successfully, the vulnerability can cause sustained memory consumption that gradually depletes available system resources, or trigger process exits that require manual intervention to restore service availability. Network administrators may observe increased memory usage patterns, process restarts, or complete service unavailability during attack periods, making this particularly dangerous in environments where DNS availability is critical for network operations. The vulnerability affects the fundamental reliability of DNS services and can be leveraged by attackers to perform sustained denial of service attacks against critical network infrastructure.
Mitigation strategies for CVE-2012-3868 primarily focus on upgrading to ISC BIND version 9.9.1-P2 or later, which includes proper synchronization fixes for the ns_client structure management. Organizations should implement rate limiting mechanisms to restrict the number of concurrent TCP connections from individual clients, thereby reducing the likelihood of triggering the race condition. Network segmentation and access control measures can help limit exposure by restricting direct access to DNS servers from untrusted networks. Additionally, monitoring systems should be configured to detect unusual patterns in DNS query volumes and memory consumption that may indicate exploitation attempts. The vulnerability demonstrates the importance of proper concurrent programming practices and highlights the need for comprehensive testing of race conditions in multi-threaded network applications, aligning with ATT&CK technique T1499.004 for network denial of service attacks. Organizations should also consider implementing intrusion detection systems that can identify and block malicious query patterns associated with this specific vulnerability.