CVE-2007-2930 in BIND
Summary
by MITRE
The (1) NSID_SHUFFLE_ONLY and (2) NSID_USE_POOL PRNG algorithms in ISC BIND 8 before 8.4.7-P1 generate predictable DNS query identifiers when sending outgoing queries such as NOTIFY messages when answering questions as a resolver, which allows remote attackers to poison DNS caches via unknown vectors. NOTE: this issue is different from CVE-2007-2926.
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Analysis
by VulDB Data Team • 06/08/2025
The vulnerability described in CVE-2007-2930 affects ISC BIND 8 versions prior to 8.4.7-P1 and specifically targets two PRNG algorithms: NSID_SHUFFLE_ONLY and NSID_USE_POOL. This weakness resides in the DNS query identifier generation mechanism that is fundamental to DNS security protocols. The flaw manifests when BIND acts as a resolver processing incoming queries or when it sends outgoing queries such as NOTIFY messages, creating a predictable pattern in the transaction identifiers used for DNS communications.
The technical root cause of this vulnerability lies in the implementation of pseudorandom number generation within the DNS resolver component of BIND 8. When using the affected PRNG algorithms, the system generates DNS query identifiers that follow predictable sequences rather than truly random patterns. This predictability occurs because the random number generator does not properly seed or shuffle its internal state, allowing attackers to compute future query identifiers that will match the expected transaction IDs in DNS responses.
The operational impact of this vulnerability is significant as it enables remote attackers to perform DNS cache poisoning attacks without direct access to the network path between client and server. The attack vector operates through the predictable nature of DNS query identifiers, allowing malicious actors to inject false DNS responses into cache storage systems. When a resolver sends a query with a predictable identifier, an attacker can respond with forged DNS data that matches the expected transaction ID, causing the resolver to store incorrect information in its cache. This behavior directly violates the fundamental security assumptions of DNS operations and undermines the integrity of DNS resolution across affected systems.
This vulnerability aligns with CWE-330, which addresses the use of insufficiently random values in security contexts, and represents a classic example of weak random number generation in network protocols. The attack pattern corresponds to techniques described in the MITRE ATT&CK framework under T1071.004 for DNS tunneling and data manipulation, where adversaries exploit predictable identifiers to compromise system integrity. The issue is distinct from CVE-2007-2926, indicating that multiple vulnerabilities exist within the same software version but affect different aspects of the DNS implementation. Organizations using affected BIND versions face potential risks including unauthorized redirection of network traffic, service disruption, and compromise of network integrity through cached malicious DNS records that can persist for extended periods.
Mitigation strategies include immediate upgrade to BIND 8.4.7-P1 or later versions that contain corrected PRNG implementations, along with implementing additional security measures such as DNSSEC validation to provide cryptographic protection against cache poisoning attacks. Network administrators should also consider implementing rate limiting and monitoring for unusual DNS query patterns that might indicate exploitation attempts. The fix addresses the core issue by ensuring proper seeding and entropy injection into the PRNG algorithms, making the generated DNS query identifiers truly unpredictable and resistant to exploitation by remote attackers.