CVE-2020-3205 in IOS
Summary
by MITRE
A vulnerability in the implementation of the inter-VM channel 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 unauthenticated, adjacent attacker to execute arbitrary shell commands on the Virtual Device Server (VDS) of an affected device. The vulnerability is due to insufficient validation of signaling packets that are destined to VDS. An attacker could exploit this vulnerability by sending malicious packets to an affected device. 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. Because the device is designed on a hypervisor architecture, exploitation of a vulnerability that affects the inter-VM channel may lead to a complete system compromise. For more information about this vulnerability, see the Details section of this advisory.
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Analysis
by VulDB Data Team • 10/21/2020
This vulnerability resides within the inter-vm channel implementation of cisco ios software affecting specific industrial integrated services routers and connected grid routers. The flaw represents a critical security weakness that allows unauthenticated adjacent attackers to execute arbitrary shell commands on the virtual device server of affected devices. The vulnerability stems from inadequate validation of signaling packets destined for the virtual device server component, creating an attack vector that bypasses normal authentication mechanisms. This issue affects cisco 809 and 829 industrial isrs as well as cisco 1000 series cgr1000 routers, all of which operate on hypervisor architectures where virtual machines communicate through inter-vm channels.
The technical exploitation of this vulnerability occurs through the transmission of malicious signaling packets to the targeted device, which then processes these packets without proper validation checks. When the virtual device server receives these malformed packets, it fails to properly sanitize the input, allowing an attacker to inject and execute arbitrary commands within the linux shell context of the vds. The privilege escalation aspect is particularly concerning as the executed commands run with root user privileges, providing attackers with complete control over the virtual device server environment. This type of vulnerability maps directly to cwe-20 input validation and cwe-78 os command injection, representing fundamental flaws in how the system handles external communications and command execution.
The operational impact of this vulnerability extends beyond simple command execution to represent a complete system compromise potential due to the hypervisor architecture of these devices. In industrial environments where these routers serve as critical infrastructure components, an attacker who successfully exploits this vulnerability could gain complete control over the device's virtualized environment. This compromise could lead to denial of service, data exfiltration, or even manipulation of industrial control systems that rely on these network devices for connectivity. The adjacent attack requirement means that an attacker must be physically present on the same network segment as the target device, but this limitation does not mitigate the severity of the potential compromise. The vulnerability creates a persistent backdoor that could allow attackers to maintain long-term access to industrial networks.
Mitigation strategies for this vulnerability should focus on network segmentation to prevent adjacent access to affected devices, implementing proper firewall rules to restrict inter-vm communication, and applying official cisco security patches as soon as they become available. Organizations should also consider network monitoring solutions that can detect anomalous signaling packet patterns that may indicate exploitation attempts. Given the nature of the vulnerability and its mapping to cwe-20 and cwe-78, defensive measures should include input validation controls and command injection prevention mechanisms. The attack pattern aligns with tactics used in the attack framework, particularly those involving privilege escalation and persistence within network infrastructure. Regular security assessments of industrial control systems should include verification of device firmware versions and implementation of network access controls to prevent unauthorized physical access to critical network infrastructure components.