CVE-2004-0230 in Solaris
Summary
by MITRE
TCP, when using a large Window Size, makes it easier for remote attackers to guess sequence numbers and cause a denial of service (connection loss) to persistent TCP connections by repeatedly injecting a TCP RST packet, especially in protocols that use long-lived connections, such as BGP.
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Analysis
by VulDB Data Team • 05/02/2025
The vulnerability described in CVE-2004-0230 represents a significant weakness in the Transmission Control Protocol's handling of large window sizes, specifically affecting how sequence number prediction operates within TCP connections. This flaw exploits the relationship between window scaling and sequence number generation, creating predictable patterns that attackers can exploit to disrupt network communications. The vulnerability manifests when TCP implementations use large window sizes, which are common in high-bandwidth networks where window scaling is employed to maximize throughput. The core issue lies in the mathematical relationship between the window size and the sequence number space, where larger windows create more predictable sequence number patterns that can be guessed by remote attackers.
The technical exploitation of this vulnerability occurs through a sophisticated attack vector that leverages the predictable nature of sequence numbers in large window scenarios. Attackers can repeatedly inject TCP RST packets at specific intervals to disrupt persistent connections, particularly targeting protocols that rely on long-lived TCP sessions such as Border Gateway Protocol. The attack works by analyzing the sequence number space and predicting when the next valid sequence number will appear, allowing the attacker to send RST packets that will be accepted by the target system. This approach specifically targets the window scaling mechanism, where the window size becomes so large that the sequence number space becomes computationally predictable, violating fundamental security assumptions about connection integrity and sequence number randomness.
The operational impact of this vulnerability extends beyond simple denial of service, creating cascading effects in network infrastructure that rely on persistent connections. Protocols like BGP, which maintain long-lived sessions between network routers, become particularly vulnerable to this attack vector, potentially causing widespread routing disruptions across internet infrastructure. The vulnerability affects systems where large window sizes are configured, which is common in high-speed networks and data center environments where throughput optimization is prioritized over security considerations. Network administrators face the challenge of identifying vulnerable systems while maintaining service availability, as the attack can be executed with minimal resources and can cause significant disruption to critical network services.
This vulnerability aligns with CWE-310, which addresses cryptographic issues related to predictable random numbers and sequence number generation, and represents a specific exploitation of the TCP protocol's window scaling implementation. The attack pattern corresponds to techniques found in the ATT&CK framework under the "Network Service Scanning" and "Resource Hijacking" categories, where adversaries target connection state information to disrupt service availability. Mitigation strategies include implementing proper TCP window scaling configurations, deploying intrusion detection systems that monitor for anomalous RST packet patterns, and ensuring that security policies account for the relationship between window size and sequence number predictability. Organizations should also consider implementing TCP sequence number randomization techniques and regularly reviewing network configurations to identify and address large window size implementations that may expose systems to this type of attack.