CVE-2007-3377 in Net Dns
Summary
by MITRE
Header.pm in Net::DNS before 0.60, a Perl module, (1) generates predictable sequence IDs with a fixed increment and (2) can use the same starting ID for all child processes of a forking server, which allows remote attackers to spoof DNS responses, as originally reported for qpsmtp and spamassassin.
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Analysis
by VulDB Data Team • 07/22/2019
The vulnerability described in CVE-2007-3377 affects the Net::DNS Perl module version 0.60 and earlier, specifically within the Header.pm component. This flaw represents a significant security weakness that undermines the integrity of DNS communications by compromising the sequence number generation mechanism. The issue manifests in two distinct but related ways that together create a pathway for sophisticated spoofing attacks. The vulnerability operates at the fundamental level of DNS protocol implementation, where predictable sequence numbers serve as a critical security mechanism for validating response authenticity.
The technical implementation of this vulnerability stems from the predictable sequence ID generation algorithm used by the Net::DNS module. When the module generates DNS header sequence IDs, it employs a fixed increment pattern that makes the sequence predictable to attackers who can observe a few consecutive transactions. Additionally, for forking server implementations, the module uses the same starting sequence ID across all child processes, creating a scenario where multiple concurrent connections share identical sequence number patterns. This combination of predictable incrementation and shared starting values eliminates the randomness that DNS security protocols rely upon for authentication and validation purposes.
The operational impact of this vulnerability extends beyond simple DNS spoofing to encompass broader security implications for email servers and spam filtering systems. The original report specifically mentions qpsmtp and spamassassin as affected components, demonstrating how this vulnerability could be exploited to compromise email security infrastructure. Attackers can leverage predictable sequence numbers to inject false DNS responses into legitimate communication channels, potentially redirecting email traffic, bypassing spam filters, or executing man-in-the-middle attacks against DNS resolution processes. This vulnerability particularly affects systems that rely on DNS for email validation and spam detection, making it a critical concern for email security implementations.
The security implications of this vulnerability align with CWE-330, which addresses the use of insecure random number generators, and can be mapped to ATT&CK technique T1071.004 for application layer protocol tunneling. The predictable sequence ID generation violates fundamental security principles for cryptographic randomness and network protocol integrity. Organizations using affected versions of Net::DNS should immediately implement mitigations including updating to version 0.60 or later, implementing additional DNS security measures such as DNSSEC, and considering network-level protections against spoofed DNS responses. The vulnerability demonstrates the critical importance of proper random number generation in security-sensitive applications and highlights the need for thorough security testing of protocol implementations.
This vulnerability type represents a classic example of how seemingly minor implementation flaws can create significant security risks in network protocols. The combination of predictable sequence numbers and shared starting values across processes creates a particularly dangerous scenario for systems that depend on DNS for authentication and validation. The impact extends beyond immediate spoofing capabilities to potentially enable more sophisticated attacks including cache poisoning and service disruption. Organizations should conduct comprehensive audits of their DNS-dependent applications and ensure that all components use secure random number generation practices to prevent similar vulnerabilities from compromising their security posture.