CVE-2007-2926 in BIND
Summary
by MITRE
ISC BIND 9 through 9.5.0a5 uses a weak random number generator during generation of DNS query ids when answering resolver questions or sending NOTIFY messages to slave name servers, which makes it easier for remote attackers to guess the next query id and perform DNS cache poisoning.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 02/02/2025
The vulnerability identified as CVE-2007-2926 represents a critical weakness in the Internet Systems Consortium BIND DNS server implementation that affects versions through 9.5.0a5. This flaw resides in the cryptographic randomness implementation used for generating DNS query identifiers during both resolver operations and slave name server notifications. The weakness specifically manifests in the random number generation algorithm employed by BIND during these critical operations, creating predictable patterns that adversaries can exploit to compromise DNS resolution integrity.
The technical flaw stems from the use of a weak random number generator within the DNS query ID generation process. When BIND handles DNS resolver queries or sends NOTIFY messages to slave servers, it relies on a pseudo-random number generator that lacks sufficient entropy and cryptographic strength. This weakness allows attackers to predict future query IDs by analyzing patterns in previously observed IDs, effectively breaking the security mechanism designed to prevent DNS cache poisoning attacks. The vulnerability directly maps to CWE-330, which addresses the use of insufficent entropy in random number generation, and aligns with ATT&CK technique T1187 for DNS tunneling and cache poisoning activities.
The operational impact of this vulnerability is severe and far-reaching within DNS infrastructure security. Remote attackers can leverage the predictable query ID generation to perform successful DNS cache poisoning attacks, where malicious responses are cached by vulnerable DNS servers and subsequently served to legitimate clients. This compromises the integrity of DNS resolution and can lead to various attack vectors including man-in-the-middle attacks, redirection of network traffic, and potential compromise of downstream systems. The vulnerability affects both primary and secondary DNS servers, making it particularly dangerous as it can propagate through DNS hierarchies and impact large-scale network operations.
Mitigation strategies for CVE-2007-2926 require immediate implementation of software updates to BIND versions that address the weak random number generation issue. Organizations should upgrade to BIND 9.5.0a6 or later releases that contain proper cryptographic random number generation implementations. Additionally, network administrators should implement DNS security measures such as DNSSEC deployment to provide additional layers of protection against cache poisoning attacks. The mitigation approach should follow NIST SP 800-57 guidelines for cryptographic key management and random number generation, ensuring that all DNS infrastructure components utilize cryptographically secure random number generators that meet industry standards for entropy and unpredictability. Network monitoring should also be enhanced to detect anomalous DNS query patterns that might indicate exploitation attempts.