CVE-2020-3208 in IOS
Summary
by MITRE
A vulnerability in the image verification feature of Cisco IOS Software for Cisco 809 and 829 Industrial Integrated Services Routers (Industrial ISRs) could allow an authenticated, local attacker to boot a malicious software image on an affected device. The vulnerability is due to insufficient access restrictions on the area of code that manages the image verification feature. An attacker could exploit this vulnerability by first authenticating to the targeted device and then logging in to the Virtual Device Server (VDS) of an affected device. The attacker could then, from the VDS shell, disable Cisco IOS Software integrity (image) verification. A successful exploit could allow the attacker to boot a malicious Cisco IOS Software image on the targeted device. To exploit this vulnerability, the attacker must have valid user credentials at privilege level 15.
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Analysis
by VulDB Data Team • 10/21/2020
The vulnerability identified as CVE-2020-3208 affects Cisco IOS Software running on Cisco 809 and 829 Industrial Integrated Services Routers, representing a critical security flaw in the image verification mechanism that could enable arbitrary code execution. This weakness resides within the access control implementation of the image verification feature, specifically targeting the code area responsible for managing software integrity checks. The vulnerability demonstrates a fundamental flaw in the principle of least privilege and proper access control enforcement, creating a pathway for authenticated local attackers to compromise device integrity and potentially gain persistent control over industrial network infrastructure.
The technical exploitation of this vulnerability requires a multi-step attack process that begins with authentication to the device using valid credentials at privilege level 15, followed by establishing a session through the Virtual Device Server interface. Once inside the VDS shell environment, attackers can manipulate the image verification process by disabling Cisco IOS Software integrity verification mechanisms. This deliberate bypass of security controls allows the attacker to subsequently boot malicious software images onto the affected device, effectively compromising the router's operational integrity. The vulnerability directly maps to CWE-284 Access Control, specifically the weakness of insufficient access restrictions on code areas responsible for critical system functions.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it enables complete compromise of the industrial router's software environment and potentially the broader network infrastructure it protects. Industrial ISRs serve as critical network gateways in industrial control systems, making this vulnerability particularly dangerous for operational technology environments. Successful exploitation could lead to complete network isolation, data exfiltration, or disruption of critical industrial processes, with potential cascading effects throughout industrial control networks. The attack vector requires local access with administrative privileges, making it less likely to be exploited remotely but still poses significant risk in environments where physical access or administrative credentials may be compromised.
Mitigation strategies for CVE-2020-3208 should focus on implementing robust access control measures and limiting administrative privileges to only essential personnel. Network segmentation and monitoring of VDS access attempts should be implemented to detect unauthorized activities. Cisco has released software updates addressing this vulnerability, and administrators should immediately apply the relevant security patches to affected devices. Additional protective measures include implementing strong authentication mechanisms, regularly reviewing access logs, and conducting security audits of industrial network devices. The vulnerability highlights the importance of proper code access restriction enforcement and demonstrates how insufficient privilege controls in system management interfaces can create pathways for complete system compromise, aligning with ATT&CK technique T1068 for Local Privilege Escalation and T1547 for Registry Run Keys. Organizations should also consider implementing device integrity monitoring solutions to detect unauthorized software installations and maintain detailed audit trails of all administrative activities on critical industrial infrastructure.