CVE-2008-4100 in adns
Summary
by MITRE
GNU adns 1.4 and earlier uses a fixed source port and sequential transaction IDs for DNS requests, which makes it easier for remote attackers to spoof DNS responses, a different vulnerability than CVE-2008-1447. NOTE: the vendor reports that this is intended behavior and is compatible with the product s intended role in a trusted environment.
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Analysis
by VulDB Data Team • 11/03/2024
The vulnerability identified as CVE-2008-4100 affects GNU adns version 1.4 and earlier, presenting a significant security weakness in DNS request handling mechanisms. This flaw resides in the network protocol implementation where the software employs a fixed source port and sequentially incremented transaction IDs for all DNS queries. The issue creates predictable patterns that adversaries can exploit to craft convincing spoofed DNS responses, potentially leading to man-in-the-middle attacks or DNS cache poisoning scenarios. The vulnerability operates independently from CVE-2008-1447, indicating distinct attack vectors and implementation flaws within the DNS resolution library.
The technical implementation flaw stems from the deterministic nature of DNS request generation within GNU adns. When the software sends DNS queries, it consistently uses the same source port number across all connections and increments transaction IDs in a predictable sequence. This predictable behavior violates fundamental security principles for network communications, as it removes the randomness that typically protects against spoofing attacks. The fixed source port eliminates the standard defense mechanism that operating systems employ to randomize ephemeral port assignments, while the sequential transaction IDs create a pattern that attackers can easily replicate. This vulnerability directly relates to CWE-310, which addresses cryptographic weakness in the generation of random numbers or identifiers, and aligns with ATT&CK technique T1071.004 for application layer protocol: DNS, where adversaries manipulate DNS responses to redirect traffic or inject malicious content.
The operational impact of this vulnerability extends beyond simple DNS spoofing to potentially compromise the integrity of network communications in environments where GNU adns is deployed. Attackers can leverage this weakness to redirect users to malicious websites, inject false DNS records into caches, or disrupt legitimate network services by exploiting the predictable transaction patterns. The vulnerability is particularly concerning in scenarios where DNS resolution is critical for security operations, such as in network monitoring systems, security appliances, or applications that rely on DNS for authentication or authorization processes. The risk is amplified in environments where network traffic is not properly secured with additional layers of protection such as DNSSEC, as the lack of randomness in source port and transaction ID generation provides attackers with sufficient information to craft successful spoofing attacks.
While the vendor has indicated that this behavior is intentional and designed for compatibility with the product's intended role in trusted environments, this designation does not diminish the security implications for deployments where such assumptions may not hold true. The recommended mitigations include upgrading to GNU adns versions beyond 1.4 where the implementation has been corrected to use randomized source ports and transaction IDs. Organizations should also implement additional network security controls such as DNSSEC validation, network segmentation, and monitoring for suspicious DNS activity. The vulnerability demonstrates the importance of considering security implications even in components that are intended for trusted environments, as the assumption of trust should not preclude the need for robust security mechanisms. Network administrators should conduct thorough assessments of their DNS infrastructure and ensure that all DNS resolution components implement proper randomization techniques to prevent similar vulnerabilities from being exploited in their environments.