CVE-2020-3217 in IOS
Summary
by MITRE
A vulnerability in the Topology Discovery Service of Cisco One Platform Kit (onePK) in Cisco IOS Software, Cisco IOS XE Software, Cisco IOS XR Software, and Cisco NX-OS Software could allow an unauthenticated, adjacent attacker to execute arbitrary code or cause a denial of service (DoS) condition on an affected device. The vulnerability is due to insufficient length restrictions when the onePK Topology Discovery Service parses Cisco Discovery Protocol messages. An attacker could exploit this vulnerability by sending a malicious Cisco Discovery Protocol message to an affected device. An exploit could allow the attacker to cause a stack overflow, which could allow the attacker to execute arbitrary code with administrative privileges, or to cause a process crash, which could result in a reload of the device and cause a DoS condition.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 10/21/2020
The vulnerability identified as CVE-2020-3217 resides within the Topology Discovery Service component of Cisco's One Platform Kit (onePK), a critical infrastructure element embedded across multiple Cisco software platforms including IOS Software, IOS XE Software, IOS XR Software, and NX-OS Software. This security flaw represents a significant concern for network infrastructure administrators as it affects a foundational discovery mechanism that helps network devices identify and map their topology. The vulnerability specifically targets the parsing logic of Cisco Discovery Protocol (CDP) messages, which are essential for network device communication and topology construction. The flaw manifests as inadequate input validation mechanisms that fail to properly restrict message lengths during processing, creating a dangerous attack surface for adjacent network adversaries.
The technical exploitation of this vulnerability occurs through the manipulation of CDP message structures, where an attacker crafts maliciously formatted packets designed to trigger a stack overflow condition within the onePK Topology Discovery Service. This insufficient length validation creates a classic buffer overflow scenario where the service attempts to process data exceeding allocated memory boundaries. The attack vector requires only adjacent network access, meaning an attacker positioned within the same network segment can exploit this weakness without requiring authentication credentials. When the malformed CDP message is processed, the service's memory management fails to handle the oversized data properly, leading to memory corruption that can either execute arbitrary code with administrative privileges or cause a controlled crash that results in device reload and subsequent denial of service conditions. This vulnerability directly maps to CWE-121, which describes stack-based buffer overflow conditions, and represents a critical weakness in input validation and memory management practices.
The operational impact of CVE-2020-3217 extends beyond simple network disruption to potentially enable complete system compromise with administrative control over affected network devices. Network administrators face the challenging scenario where an unauthenticated attacker within the same broadcast domain can escalate privileges and gain full control over routers, switches, and other network infrastructure components. The potential for remote code execution with administrative privileges creates a severe risk for enterprise networks, as attackers could manipulate routing tables, intercept traffic, or establish persistent access points within the network. The denial of service component of this vulnerability compounds the risk by potentially causing network outages that could affect business continuity and critical infrastructure operations. According to ATT&CK framework, this vulnerability aligns with T1059.007 for remote code execution and T1499.004 for network disruption, while also mapping to T1071.001 for application layer protocol usage and T1046 for network service discovery, demonstrating the multi-faceted attack surface this vulnerability exposes.
Mitigation strategies for CVE-2020-3217 require immediate implementation of network segmentation and access control measures to limit adjacent network access to critical infrastructure devices. Cisco recommends applying the latest software patches that address the buffer overflow condition in the onePK Topology Discovery Service parsing logic, which typically involves updating to patched versions of IOS, IOS XE, IOS XR, or NX-OS software releases. Network administrators should implement access control lists and firewall rules to restrict CDP message processing to trusted network segments, effectively limiting the attack surface. Additionally, monitoring and logging of CDP traffic can help detect anomalous message patterns that may indicate exploitation attempts. The implementation of network access control protocols and disabling CDP on unnecessary interfaces provides additional layers of protection. Organizations should also consider network segmentation strategies that isolate critical infrastructure from general network access, reducing the likelihood of adjacent attackers reaching vulnerable devices. Regular vulnerability assessments and network scanning should be conducted to identify any remaining unpatched systems, while security awareness training for network administrators helps ensure proper configuration practices that prevent exploitation of this and similar vulnerabilities.