CVE-2011-1907 in BIND
Summary
by MITRE
ISC BIND 9.8.x before 9.8.0-P1, when Response Policy Zones (RPZ) RRset replacement is enabled, allows remote attackers to cause a denial of service (assertion failure and daemon exit) via an RRSIG query.
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Analysis
by VulDB Data Team • 12/28/2024
The vulnerability identified as CVE-2011-1907 affects ISC BIND version 9.8.x prior to patch level 9.8.0-P1 and specifically targets the Response Policy Zones functionality within the DNS server implementation. This issue represents a critical denial of service vulnerability that can be exploited by remote attackers to crash the BIND daemon through carefully crafted RRSIG queries. The vulnerability resides in the handling of DNS resource records when RPZ replacement mechanisms are active, creating a scenario where legitimate DNS queries can trigger internal assertion failures that cause the daemon to terminate unexpectedly.
The technical flaw manifests when the BIND server processes RRSIG records in conjunction with Response Policy Zones functionality that replaces RRsets. When an attacker submits a malicious RRSIG query while RPZ replacement is enabled, the server's internal validation logic fails to properly handle the specific combination of record types and replacement operations. This causes an assertion failure within the DNS server code, leading to an unhandled exception that results in the daemon exiting and ceasing to provide DNS services to legitimate clients. The vulnerability specifically impacts the server's ability to maintain stable operation under normal query loads when certain RPZ configurations are active.
The operational impact of this vulnerability extends beyond simple service interruption as it can be exploited by remote attackers without requiring authentication or privileged access. The denial of service condition affects the availability of DNS services for all clients relying on the affected BIND server, potentially disrupting network connectivity and application availability across the entire domain. This vulnerability is particularly concerning in environments where BIND serves as a critical infrastructure component for DNS resolution, as the attack can be executed from any network location without requiring local access to the server. The vulnerability affects both authoritative and recursive DNS server implementations, making it applicable to a wide range of deployment scenarios.
Mitigation strategies for CVE-2011-1907 primarily involve applying the official patch release 9.8.0-P1 from ISC BIND, which addresses the assertion failure in the RPZ processing logic. Organizations should also consider implementing temporary workarounds such as disabling Response Policy Zones functionality when not actively required, or restricting RRSIG query processing through firewall rules. Network administrators should monitor for exploitation attempts and implement intrusion detection systems to identify potential attacks targeting this vulnerability. The fix addresses the underlying CWE-248 issue related to unspecified other errors and aligns with the ATT&CK technique T1499.004 for network denial of service attacks. Additionally, organizations should conduct thorough testing of the patched software to ensure no regressions in DNS service functionality and review their RPZ configurations to minimize exposure to similar vulnerabilities in the future.