CVE-2001-0497 in BIND
Summary
by MITRE
dnskeygen in BIND 8.2.4 and earlier, and dnssec-keygen in BIND 9.1.2 and earlier, set insecure permissions for a HMAC-MD5 shared secret key file used for DNS Transactional Signatures (TSIG), which allows attackers to obtain the keys and perform dynamic DNS updates.
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Analysis
by VulDB Data Team • 03/21/2017
The vulnerability identified as CVE-2001-0497 represents a critical security flaw in the Berkeley Internet Name Domain (BIND) software family that affected versions 8.2.4 and earlier, as well as 9.1.2 and earlier releases. This issue specifically impacts the dnskeygen utility in BIND 8 and the dnssec-keygen utility in BIND 9, which are responsible for generating cryptographic keys used in DNS Security Extensions. The flaw manifests when these tools create HMAC-MD5 shared secret key files necessary for DNS Transaction Signatures, which are essential for authenticating dynamic DNS updates and ensuring the integrity of DNS communications. The vulnerability stems from improper file permission settings during key generation, creating a significant attack surface that compromises the entire DNS security infrastructure.
The technical nature of this vulnerability resides in the insecure default permissions assigned to the generated key files, which typically creates files with world-readable and world-writable permissions. This flaw directly maps to CWE-732, which categorizes improper permission settings for critical security resources, and represents a classic privilege escalation vector within DNS infrastructure. When attackers gain access to these HMAC-MD5 keys through the insecure file permissions, they can effectively impersonate legitimate DNS servers and perform unauthorized dynamic DNS updates. This capability allows adversaries to inject malicious DNS records, redirect traffic, or create unauthorized zones, fundamentally undermining the trust model that DNSSEC is designed to protect. The impact extends beyond simple data manipulation as attackers can leverage these keys to conduct cache poisoning attacks, perform man-in-the-middle operations, or execute broader network reconnaissance activities that compromise the entire DNS ecosystem.
The operational impact of CVE-2001-0497 is severe and far-reaching across enterprise and internet infrastructure, as it enables attackers to compromise the fundamental authentication mechanisms of DNS systems. Organizations running affected BIND versions face the risk of complete DNS compromise, where malicious actors can modify DNS records in real-time without detection, potentially redirecting users to phishing sites or malicious services. This vulnerability particularly affects dynamic DNS environments where updates are frequently performed, as the insecure key files provide attackers with persistent access to update mechanisms. The attack vector aligns with techniques described in the MITRE ATT&CK framework under T1071.004 for DNS tunneling and T1566 for credential access, as the compromised keys can be used to establish persistent access to DNS infrastructure. The vulnerability's exploitation requires minimal technical skill and can be automated, making it particularly dangerous for organizations with multiple DNS servers or those operating in high-risk threat environments.
Mitigation strategies for CVE-2001-0497 focus on immediate remediation through software updates to patched versions of BIND that properly enforce secure file permissions. Organizations should immediately upgrade to BIND versions 8.2.5 and 9.1.3 or later, which address the insecure permission handling in key generation utilities. System administrators must also conduct thorough audits of existing key files to identify any compromised HMAC-MD5 keys and regenerate all DNS security keys with proper permissions. The implementation of the principle of least privilege should be enforced, ensuring that key files are created with restrictive permissions such as 600 or 640, and that only authorized processes can access these critical security resources. Additional defensive measures include implementing network monitoring for unauthorized DNS update activities, deploying DNS security monitoring tools, and establishing regular security audits of DNS infrastructure to detect and remediate similar permission-based vulnerabilities. Organizations should also consider implementing additional authentication layers beyond TSIG, such as DNS over TLS or DNS over HTTPS, to provide redundancy and additional protection against key compromise scenarios.