CVE-2000-0887 in BIND
Summary
by MITRE
named in BIND 8.2 through 8.2.2-P6 allows remote attackers to cause a denial of service by making a compressed zone transfer (ZXFR) request and performing a name service query on an authoritative record that is not cached, aka the "zxfr bug."
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Analysis
by VulDB Data Team • 10/12/2025
The CVE-2000-0887 vulnerability represents a critical denial of service flaw in the Berkeley Internet Name Domain software version 8.2 through 8.2.2-P6. This vulnerability specifically targets the named daemon's handling of compressed zone transfer requests, creating a condition where remote attackers can disrupt DNS services without requiring authentication or specialized privileges. The flaw exists within the zone transfer mechanism that processes compressed DNS records, making it particularly dangerous as it can affect any system running affected versions of BIND software.
The technical root cause of this vulnerability lies in the improper handling of compressed resource records during zone transfer operations. When a compressed zone transfer request is made to a vulnerable BIND server, the system processes the request in a manner that leads to memory corruption or excessive resource consumption. The vulnerability specifically manifests when an authoritative DNS record that is not currently cached is queried during the zone transfer process. This creates a scenario where the named daemon enters an infinite loop or consumes excessive memory resources, ultimately leading to service unavailability. The issue is classified as a weakness in the implementation of DNS zone transfer protocols and falls under the CWE-121 category of buffer overflow conditions, specifically involving improper handling of compressed data structures.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise entire DNS infrastructure operations. Organizations relying on affected BIND versions experience complete denial of service for their DNS services, preventing legitimate clients from resolving domain names and accessing network resources. This vulnerability affects critical network infrastructure components including authoritative name servers, recursive resolvers, and caching servers that depend on the named daemon. Attackers can exploit this vulnerability with minimal resources and technical expertise, making it particularly dangerous for large organizations with extensive DNS deployments. The impact is exacerbated when attackers target high-traffic DNS servers, as the denial of service can affect thousands of legitimate users simultaneously.
Mitigation strategies for CVE-2000-0887 require immediate patching of affected BIND installations to versions that properly handle compressed zone transfer requests. Organizations should implement network-level protections such as access control lists that restrict zone transfer requests to trusted sources only, thereby limiting exposure to remote attackers. The implementation of monitoring systems that detect unusual zone transfer patterns and memory consumption spikes can help identify exploitation attempts before they cause significant damage. Additionally, administrators should consider disabling zone transfer functionality where it is not strictly required, particularly for authoritative servers that do not need to maintain secondary copies of zone data. This vulnerability aligns with ATT&CK technique T1499.004 which covers network denial of service attacks and demonstrates the importance of proper input validation and resource management in DNS server implementations. Organizations should also implement redundant DNS infrastructure and failover mechanisms to ensure continued service availability during exploitation attempts. The fix for this vulnerability required changes to the BIND zone transfer handling code to properly validate compressed record structures and prevent resource exhaustion during zone transfer operations.