CVE-2015-8000 in BIND
Summary
by MITRE
db.c in named in ISC BIND 9.x before 9.9.8-P2 and 9.10.x before 9.10.3-P2 allows remote attackers to cause a denial of service (REQUIRE assertion failure and daemon exit) via a malformed class attribute.
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Analysis
by VulDB Data Team • 07/01/2022
The vulnerability identified as CVE-2015-8000 affects the Internet Systems Consortium BIND DNS server software, specifically impacting versions prior to 9.9.8-P2 and 9.10.3-P2. This issue resides within the db.c component of the named daemon, which handles database operations for DNS zone data. The vulnerability represents a significant security concern as it enables remote attackers to trigger a denial of service condition that results in the daemon exiting unexpectedly. The flaw manifests when the system processes malformed class attributes in DNS queries, leading to an REQUIRE assertion failure that terminates the named process. This type of vulnerability falls under CWE-129 Input Validation, specifically targeting improper handling of malformed input data within a critical system component. The attack vector requires only network access to the affected DNS server, making it particularly dangerous as it can be exploited by anyone with network connectivity to the target system. The impact extends beyond simple service disruption as the daemon termination can lead to complete DNS service unavailability, potentially affecting thousands of dependent systems that rely on the affected server for domain resolution.
The technical implementation of this vulnerability stems from inadequate input validation within the DNS database processing logic. When the named daemon receives a DNS query containing a malformed class attribute, the db.c module fails to properly validate the input before attempting to process it. The REQUIRE assertion mechanism, designed to catch programming errors and invalid conditions during development, is triggered by the malformed data, causing the daemon to exit immediately rather than gracefully handling the error condition. This behavior represents a classic case of improper error handling and input sanitization, where the software fails to anticipate and properly manage unexpected input patterns. The vulnerability demonstrates a weakness in the software's defensive programming practices, specifically the lack of robust input validation that would have prevented the malformed class attribute from reaching the assertion check. From an operational perspective, this vulnerability aligns with ATT&CK technique T1499.004 Network Denial of Service, as it enables adversaries to disrupt network services through targeted exploitation of application-level flaws. The fact that this vulnerability affects multiple minor versions of the software indicates a systemic issue in the codebase rather than an isolated incident, suggesting that the root cause likely involves fundamental design decisions in how class attributes are processed within the DNS database subsystem.
The operational impact of CVE-2015-8000 extends far beyond the immediate denial of service condition, as DNS servers form the backbone of internet infrastructure and service availability. When a named daemon terminates due to this vulnerability, it can result in cascading failures across networks that depend on the affected server for domain name resolution. Organizations may experience complete service outages as applications and users lose the ability to resolve domain names, potentially affecting web browsing, email services, and other internet-dependent operations. The vulnerability's remote exploitability means that attackers do not require physical access or local network privileges to cause disruption, making it particularly dangerous for publicly accessible DNS servers. Recovery from such an attack requires manual intervention to restart the named service, and in some cases, the system may need to be rebooted to fully restore normal operations. The vulnerability also impacts the overall security posture of affected organizations, as it demonstrates poor input validation practices that could potentially be exploited for more sophisticated attacks if combined with other vulnerabilities. From a compliance standpoint, this vulnerability may violate security standards such as those outlined in the NIST Cybersecurity Framework, particularly in areas related to system resilience and vulnerability management. The issue represents a failure to implement proper defensive measures against malformed input, which is a fundamental requirement for maintaining secure network services. Organizations running affected versions of BIND should prioritize immediate patching to prevent exploitation, as the vulnerability provides no benefit to legitimate users while offering significant disruption potential to attackers. The remediation process involves upgrading to patched versions of BIND that contain proper input validation and error handling mechanisms, ensuring that malformed class attributes are either rejected or properly processed without causing daemon termination.