CVE-2006-2288 in Avahi
Summary
by MITRE
Avahi before 0.6.10 allows local users to cause a denial of service (mDNS/DNS-SD service disconnect) via unspecified mDNS name conflicts.
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Analysis
by VulDB Data Team • 07/26/2018
The vulnerability identified as CVE-2006-2288 affects Avahi versions prior to 0.6.10 and represents a significant denial of service weakness within the mDNS/DNS-SD service implementation. This issue specifically targets the multicast dns resolver component that is integral to Avahi's functionality for service discovery on local networks. The flaw manifests when local users can trigger mDNS name conflicts that lead to service disruption, effectively disconnecting mDNS/DNS-SD services from operating normally. The vulnerability falls under the category of improper handling of network name resolution conflicts, which is classified as CWE-129 in the Common Weakness Enumeration catalog. This weakness specifically relates to the inadequate management of resource conflicts within network protocols, particularly those involving name resolution mechanisms.
The technical implementation of this vulnerability stems from the mDNS protocol's handling of name conflicts during service registration and discovery processes. When multiple services attempt to register the same name on the same network segment, the mDNS protocol should gracefully handle these conflicts through proper conflict resolution mechanisms. However, in Avahi versions before 0.6.10, the software failed to properly manage these scenarios, allowing local users to craft specific mDNS packets or service registrations that would cause the daemon to disconnect from the network service. This behavior aligns with ATT&CK technique T1499.001 which involves network denial of service attacks targeting service availability. The vulnerability is particularly concerning because it requires only local system access to exploit, making it accessible to any user with basic system privileges.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise entire network discovery mechanisms within affected environments. When the mDNS/DNS-SD service becomes disconnected, all applications relying on Avahi for service discovery will lose their ability to locate network resources automatically. This affects desktop environments where users expect automatic discovery of printers, file shares, and other network services. The disruption can cascade through various network-dependent applications and may require manual intervention to restore service availability. Organizations relying on Avahi for zero-configuration networking may experience significant operational degradation, particularly in environments where automatic service discovery is critical for user productivity. The vulnerability also demonstrates poor input validation and error handling within the mDNS implementation, which represents a broader class of issues classified under CWE-20 for improper input validation.
Mitigation strategies for CVE-2006-2288 involve immediate upgrading to Avahi version 0.6.10 or later, which contains the necessary patches to properly handle mDNS name conflicts without causing service disconnections. System administrators should also implement network monitoring to detect unusual mDNS traffic patterns that might indicate exploitation attempts. Additional protective measures include restricting local user privileges where possible and implementing network segmentation to limit the potential impact of local privilege escalation. The fix implemented in version 0.6.10 addresses the core issue by improving the conflict resolution algorithm to properly handle name conflicts without terminating the mDNS service. Organizations should also consider implementing intrusion detection systems that can monitor for mDNS-related anomalies and establish proper patch management procedures to ensure timely deployment of security fixes. This vulnerability highlights the importance of robust error handling in network protocols and demonstrates how seemingly minor implementation flaws can lead to significant service availability issues. The fix addresses the fundamental weakness in the mDNS implementation that allowed local users to manipulate service registration processes to cause unintended service termination, thereby maintaining the integrity and availability of network discovery services.