CVE-2001-0750 in IOS
Summary
by MITRE
Cisco IOS 12.1(2)T, 12.1(3)T allow remote attackers to cause a denial of service (reload) via a connection to TCP ports 3100-3999, 5100-5999, 7100-7999 and 10100-10999.
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Analysis
by VulDB Data Team • 05/09/2019
Cisco IOS version 12.1(2)T and 12.1(3)T contains a critical vulnerability that allows remote attackers to trigger a denial of service condition resulting in system reload. This vulnerability specifically targets connections made to TCP ports within four distinct ranges including 3100-3999, 5100-5999, 7100-7999, and 10100-10999. The flaw represents a failure in the IOS operating system's packet processing logic where malformed or specially crafted connections to these port ranges can cause the router to crash and automatically reload. This vulnerability falls under the CWE-119 category of memory corruption issues, specifically representing an improper restriction of operations within a limited access scope. The attack vector is particularly concerning as it requires no authentication and can be executed from remote locations, making it a significant threat to network infrastructure availability. The operational impact of this vulnerability extends beyond simple service disruption as the automatic reload process can result in temporary network outages that may affect critical business operations and require manual intervention to restore normal functionality.
The technical implementation of this vulnerability demonstrates a classic buffer overflow condition where the IOS software fails to properly validate incoming connection data when processing traffic on the specified TCP port ranges. This validation failure allows attackers to send malformed packets that trigger memory corruption within the router's processing stack, ultimately leading to the system crash and reload behavior. The affected port ranges suggest that the vulnerability may be related to specific service implementations or protocols that operate within these ranges, potentially including various network management protocols or application-layer services. From an ATT&CK framework perspective, this vulnerability maps to the T1499.004 technique for network denial of service, specifically targeting network infrastructure devices through protocol-based attacks. The vulnerability's exploitability is enhanced by the fact that these port ranges are commonly used for legitimate network services, making the attack more difficult to detect and filter at network boundaries.
Mitigation strategies for this vulnerability should focus on immediate network segmentation and access control measures to prevent unauthorized access to the affected port ranges. Network administrators should implement firewall rules to block incoming connections to the specified TCP port ranges from untrusted networks, while also considering the implementation of intrusion detection systems that can monitor for suspicious traffic patterns on these ports. The most effective immediate solution involves upgrading to Cisco IOS versions that have been patched to address this vulnerability, as the official fix resolves the underlying buffer overflow condition in the packet processing code. Organizations should also conduct comprehensive network audits to identify all devices running the vulnerable IOS versions and prioritize their remediation efforts based on network criticality and exposure levels. Additionally, implementing network monitoring solutions that can detect unusual reload patterns or connection attempts to these specific port ranges can provide early warning capabilities for potential exploitation attempts. The vulnerability highlights the importance of maintaining current firmware versions and implementing robust network access controls to prevent unauthorized remote access to network infrastructure devices.