CVE-2000-0692 in RealSecure
Summary
by MITRE
ISS RealSecure 3.2.1 and 3.2.2 allows remote attackers to cause a denial of service via a flood of fragmented packets with the SYN flag set.
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Analysis
by VulDB Data Team • 05/27/2018
The vulnerability identified as CVE-2000-0692 affects ISS RealSecure network intrusion detection systems version 3.2.1 and 3.2.2, representing a significant weakness in network security monitoring capabilities. This flaw manifests as a denial of service condition that can be triggered remotely through the deliberate flooding of network traffic consisting of fragmented packets with the SYN flag activated. The vulnerability resides within the packet processing logic of the RealSecure system, specifically in how it handles fragmented TCP packets during the initial connection establishment phase. The issue stems from inadequate validation and processing of fragmented packet sequences, particularly those containing the SYN flag that signals the beginning of a TCP three-way handshake process.
The technical exploitation of this vulnerability involves sending a large volume of fragmented packets that have the SYN flag set, creating a condition where the RealSecure system becomes overwhelmed during its attempt to reconstruct and process these fragmented segments. The system's packet reassembly mechanism fails to properly handle the abnormal packet flow, leading to resource exhaustion and ultimately causing the intrusion detection system to become unresponsive or crash entirely. This type of attack directly impacts the availability of the security monitoring infrastructure, effectively creating a situation where the very system designed to protect against network threats becomes vulnerable to being disabled by malicious actors. The flaw demonstrates a classic buffer overflow or resource exhaustion pattern that has been documented in various network security contexts and aligns with CWE-129, which addresses improper handling of length values and count parameters.
The operational impact of this vulnerability extends beyond simple system downtime, as it fundamentally compromises the security posture of networks relying on ISS RealSecure for intrusion detection. When the system becomes unresponsive due to this denial of service attack, organizations lose their ability to monitor and detect malicious network activity, creating a window of opportunity for attackers to conduct other types of network intrusions without detection. This vulnerability can be exploited by attackers with minimal technical expertise, as it requires only the ability to send network packets to the targeted RealSecure system. The attack vector operates at the network layer, making it particularly dangerous as it can be launched from anywhere on the internet and does not require any authentication or privileged access to the target system. Organizations may experience cascading effects where the failure of the intrusion detection system leads to broader security failures and potential data breaches.
Mitigation strategies for this vulnerability should focus on immediate patching of affected systems, as the ISS RealSecure 3.2.3 version and later releases contain fixes for this specific issue. Network administrators should implement rate limiting and packet filtering rules to prevent excessive fragmented SYN packets from reaching the RealSecure system, particularly when these packets arrive in rapid succession. The implementation of network segmentation and the use of redundant intrusion detection systems can help maintain security monitoring capabilities even if one system becomes compromised. Additionally, organizations should consider implementing monitoring and alerting mechanisms that can detect unusual packet patterns and trigger automated responses when potential exploitation attempts are observed. This vulnerability highlights the importance of maintaining up-to-date security infrastructure and following the principles outlined in the ATT&CK framework for network security operations, specifically addressing the techniques related to denial of service and network infiltration. The incident serves as a reminder of the critical need for robust input validation and resource management in security appliances, as well as the necessity of thorough testing of security systems against various attack vectors before deployment in production environments.