CVE-2002-0813 in IOS
Summary
by MITRE
Heap-based buffer overflow in the TFTP server capability in Cisco IOS 11.1, 11.2, and 11.3 allows remote attackers to cause a denial of service (reset) or modify configuration via a long filename.
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Analysis
by VulDB Data Team • 09/08/2024
The vulnerability identified as CVE-2002-0813 represents a critical heap-based buffer overflow within the Trivial File Transfer Protocol server implementation of Cisco IOS operating systems. This flaw affects versions 11.1, 11.2, and 11.3, making it particularly concerning given the widespread deployment of these IOS versions across enterprise networks and telecommunications infrastructure. The vulnerability specifically manifests when the TFTP server processes incoming requests with excessively long filenames, creating a condition where memory allocation occurs without proper bounds checking, leading to memory corruption in the heap allocation space.
The technical exploitation of this vulnerability occurs through carefully crafted TFTP requests that contain filenames exceeding the allocated buffer size. When the TFTP server receives such a request, the insufficient input validation causes the system to write data beyond the intended memory boundaries, resulting in heap corruption that can trigger unpredictable behavior. This heap-based buffer overflow presents a significant risk because it can be exploited remotely without requiring authentication, allowing attackers to leverage the vulnerability from outside the network perimeter. The nature of heap corruption means that the memory layout can be altered in ways that may not immediately crash the system but instead cause subtle behavior changes that could be exploited for more sophisticated attacks.
The operational impact of this vulnerability extends beyond simple denial of service conditions, as the remote exploitation capabilities create multiple attack vectors for malicious actors. A successful exploitation can cause the TFTP server to reset, effectively disrupting file transfer operations and potentially affecting network management functions that rely on TFTP for configuration updates and firmware deployments. Additionally, the ability to modify configuration data through this vulnerability presents a more severe threat, as attackers could potentially alter network settings, compromise network integrity, or establish persistent access points within the infrastructure. The vulnerability's classification under CWE-121 heap-based buffer overflow aligns with the broader category of memory safety issues that have historically led to system instability and potential privilege escalation scenarios.
Mitigation strategies for CVE-2002-0813 should prioritize immediate patching of affected Cisco IOS versions, as the vulnerability has been addressed through official security updates from Cisco. Network administrators should disable TFTP server functionality when not required, as this reduces the attack surface and eliminates the primary exploitation vector. The implementation of network segmentation and access controls can further limit the potential impact of successful exploitation attempts. Security monitoring should include detection of unusual TFTP traffic patterns and malformed filename requests that could indicate exploitation attempts. From an ATT&CK framework perspective, this vulnerability maps to techniques involving remote service exploitation and privilege escalation, with the TFTP server serving as a potential entry point for attackers seeking to establish persistent access or conduct more sophisticated network reconnaissance activities. Organizations should also consider implementing network-based intrusion detection systems that can identify and alert on suspicious TFTP traffic patterns that may indicate exploitation attempts against this specific vulnerability.