CVE-2002-2052 in IOS
Summary
by MITRE
Cisco 2611 router running IOS 12.1(6.5), possibly an interim release, allows remote attackers to cause a denial of service via port scans such as (1) scanning all ports on a single host and (2) scanning a network of hosts for a single open port through the router. NOTE: the vendor could not reproduce this issue, saying that the original reporter was using an interim release of the software.
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Analysis
by VulDB Data Team • 06/28/2021
The vulnerability described in CVE-2002-2052 affects Cisco 2611 routers operating with IOS version 12.1(6.5), which represents an interim release of the software. This issue manifests as a remote denial of service condition that can be triggered through specific port scanning activities. The vulnerability demonstrates the inherent risks associated with interim software releases that may contain undocumented flaws or incomplete implementations of security features. Network administrators and security professionals must understand that even minor version increments in network infrastructure software can introduce unexpected behaviors that compromise system availability and operational integrity.
The technical flaw involves how the router processes incoming port scan traffic, specifically when handling large volumes of port scanning attempts directed through the device. When attackers perform port scans such as scanning all ports on a single host or scanning multiple hosts for a single open port, the router's processing mechanisms become overwhelmed or enter an unstable state. This behavior represents a classic resource exhaustion vulnerability where the system's ability to handle legitimate network traffic becomes compromised. The vulnerability operates at the network layer where the router's packet processing and connection tracking mechanisms fail to properly handle the volume and pattern of scan traffic, leading to service disruption rather than simple packet filtering failure.
The operational impact of this vulnerability extends beyond simple service interruption, potentially affecting network availability and reliability for legitimate users. When a router becomes unresponsive due to port scan traffic, it can cause cascading failures throughout the network infrastructure, particularly in environments where the router serves as a critical gateway or border device. This vulnerability particularly affects network security monitoring and penetration testing activities, as security professionals may inadvertently trigger the denial of service condition while conducting legitimate security assessments. The issue also demonstrates the importance of proper software validation and testing procedures, as the vendor's inability to reproduce the problem suggests that the vulnerability may be environment-specific or dependent on particular network configurations.
Organizations should implement several mitigation strategies to address this vulnerability, including deploying network access control lists to limit port scanning traffic, configuring router logging to detect unusual scanning patterns, and implementing network segmentation to isolate vulnerable devices. The vulnerability aligns with attack patterns documented in the attack tree framework where initial reconnaissance activities can escalate to full system compromise. Security practitioners should also consider upgrading to stable software releases that have undergone comprehensive testing and validation, as interim releases often contain untested code that can introduce unexpected behaviors. Additionally, implementing rate limiting and connection tracking mechanisms can help prevent the exploitation of similar vulnerabilities in network infrastructure devices. This case highlights the broader challenge of maintaining secure network operations where even seemingly benign network activities can trigger system instability, emphasizing the need for comprehensive security testing and validation of all network infrastructure software components.