CVE-2020-3210 in IOS
Summary
by MITRE
A vulnerability in the CLI parsers of Cisco IOS Software for Cisco 809 and 829 Industrial Integrated Services Routers (Industrial ISRs) and Cisco 1000 Series Connected Grid Routers (CGR1000) could allow an authenticated, local attacker to execute arbitrary shell commands on the Virtual Device Server (VDS) of an affected device. The attacker must have valid user credentials at privilege level 15. The vulnerability is due to insufficient validation of arguments that are passed to specific VDS-related CLI commands. An attacker could exploit this vulnerability by authenticating to the targeted device and including malicious input as the argument of an affected command. A successful exploit could allow the attacker to execute arbitrary commands in the context of the Linux shell of VDS with the privileges of the root user.
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Analysis
by VulDB Data Team • 10/21/2020
This vulnerability exists within the command line interface parsers of Cisco IOS Software running on specific industrial router models including the Cisco 809 and 829 Industrial ISRs and the Cisco 1000 Series CGR1000 routers. The flaw represents a critical security weakness that allows authenticated local attackers with privilege level 15 credentials to execute arbitrary shell commands on the Virtual Device Server component of these devices. The vulnerability stems from inadequate input validation mechanisms within the CLI parser for certain VDS-related commands, creating a path for command injection attacks. This issue is particularly concerning because it operates at the privilege level 15, which typically represents the highest user privilege level in Cisco IOS environments, requiring attackers to already have legitimate administrative credentials to exploit the vulnerability.
The technical exploitation of this vulnerability occurs through the manipulation of CLI command arguments that are passed to specific VDS-related commands. When an authenticated user with privilege level 15 inputs maliciously crafted arguments into these commands, the insufficient validation allows the system to process these inputs without proper sanitization. The parsed arguments are then executed within the Linux shell context of the Virtual Device Server, effectively elevating the attacker's privileges to root level execution. This creates a severe escalation of privileges scenario where legitimate administrative access can be leveraged to gain complete system control. The vulnerability aligns with CWE-78, which describes improper neutralization of special elements used in OS commands, and CWE-20, which covers input validation issues that can lead to command injection attacks.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with complete control over the Virtual Device Server component of these industrial routers. This control enables attackers to modify system configurations, install malicious software, access sensitive data, and potentially disrupt critical industrial operations. For industrial environments using these specific router models, the implications are particularly severe as these devices often serve as critical communication infrastructure for grid operations and industrial control systems. The vulnerability essentially transforms legitimate administrative access into a complete system compromise, allowing attackers to manipulate the underlying Linux environment that supports the router's operations. This scenario represents a significant threat to industrial cybersecurity frameworks and aligns with ATT&CK technique T1059.004, which covers command and scripting interpreter for execution through shell commands.
Mitigation strategies for this vulnerability should focus on immediate patching of affected Cisco IOS Software versions, as well as implementing strict access controls and monitoring for suspicious CLI command usage. Organizations should ensure that privilege level 15 accounts are properly managed with strong authentication mechanisms and regular access reviews. Network segmentation and monitoring of CLI activity can help detect anomalous command execution patterns that might indicate exploitation attempts. Additionally, implementing principle of least privilege practices and regularly reviewing user access permissions can reduce the attack surface. Cisco has released security advisories and patches addressing this vulnerability, and organizations should prioritize applying these updates to prevent exploitation. The vulnerability also highlights the importance of input validation in embedded systems and industrial control environments where such security flaws can have cascading effects on operational technology infrastructure.