CVE-2003-1132 in Content Services Switch 11500
Summary
by MITRE
The DNS server for Cisco Content Service Switch (CSS) 11000 and 11500, when prompted for a nonexistent AAAA record, responds with response code 3 (NXDOMAIN or "Name Error") instead of response code 0 ("No Error"), which allows remote attackers to cause a denial of service (inaccessible domain) by forcing other DNS servers to send and cache a request for a AAAA record to the vulnerable server.
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Analysis
by VulDB Data Team • 07/16/2024
The vulnerability identified as CVE-2003-1132 affects Cisco Content Service Switch models 11000 and 11500, specifically within their DNS server implementation. This flaw represents a deviation from standard DNS protocol behavior where the server fails to properly handle requests for AAAA records, which are used for IPv6 address resolution. The issue stems from the server's incorrect response code handling during query processing, creating a predictable pattern that can be exploited by malicious actors. The vulnerability is classified under CWE-200, which encompasses improper error handling and information exposure in network services, making it particularly concerning for network infrastructure components that serve as DNS servers.
The technical implementation of this vulnerability lies in the DNS server's response mechanism when encountering nonexistent AAAA records. According to DNS protocol specifications, when a DNS server receives a query for a record type that does not exist, it should respond with a response code of 0, indicating "No Error" and providing a proper NXDOMAIN response for the specific record type requested. However, the vulnerable Cisco CSS devices respond with response code 3, which explicitly indicates NXDOMAIN, but in an incorrect context that triggers cascading DNS resolution failures. This behavior creates a scenario where legitimate DNS queries become corrupted in the caching mechanism of other DNS servers, leading to extended periods of domain unavailability.
The operational impact of this vulnerability extends beyond simple denial of service, creating cascading failures throughout DNS resolution systems. When attackers force other DNS servers to query the vulnerable Cisco CSS device for nonexistent AAAA records, these servers cache the erroneous responses and subsequently fail to resolve domain names properly. This creates a persistent denial of service condition that affects not just the specific vulnerable device but potentially entire domains or services that rely on proper DNS resolution. The vulnerability aligns with ATT&CK technique T1499.004, which involves network denial of service through manipulation of DNS records and caching behavior.
Mitigation strategies for this vulnerability should focus on both immediate operational responses and long-term architectural improvements. Network administrators should implement DNS server configurations that prevent caching of erroneous NXDOMAIN responses from vulnerable devices, utilize DNS query filtering to block AAAA record requests to known vulnerable systems, and deploy DNS monitoring tools that can detect and alert on abnormal response code patterns. Additionally, organizations should prioritize upgrading affected Cisco CSS devices to versions that properly implement DNS response code handling, as this vulnerability represents a fundamental flaw in DNS protocol compliance that could potentially be exploited in more sophisticated attack scenarios. The vulnerability demonstrates the critical importance of proper DNS server implementation and the potential for seemingly minor protocol deviations to create significant operational disruptions.