CVE-2020-3216 in IOS XE SD-WAN
Summary
by MITRE
A vulnerability in Cisco IOS XE SD-WAN Software could allow an unauthenticated, physical attacker to bypass authentication and gain unrestricted access to the root shell of an affected device. The vulnerability exists because the affected software has insufficient authentication mechanisms for certain commands. An attacker could exploit this vulnerability by stopping the boot initialization of an affected device. A successful exploit could allow the attacker to bypass authentication and gain unrestricted access to the root shell of the affected device.
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Analysis
by VulDB Data Team • 10/21/2020
This vulnerability resides within Cisco IOS XE SD-WAN Software, representing a critical authentication bypass flaw that fundamentally compromises device security through physical access exploitation. The vulnerability stems from insufficient authentication mechanisms specifically designed for certain administrative commands, creating a pathway for unauthorized access that bypasses normal security controls. The flaw is particularly concerning because it requires only physical access to the device and the ability to interrupt the boot process, making it accessible to attackers who can physically interact with the target equipment.
The technical execution of this vulnerability involves an attacker stopping the boot initialization process of an affected device, which then allows them to access the device's underlying system shell. This exploitation method leverages the device's boot sequence to gain access to the root shell, effectively granting complete administrative control over the affected system. The vulnerability operates at a fundamental level within the software's boot process, where normal authentication checks are bypassed or circumvented, allowing for unrestricted access to system-level commands and resources. This represents a classic example of a privilege escalation vulnerability that occurs at the system initialization phase rather than during normal operational runtime.
The operational impact of this vulnerability is severe and potentially catastrophic for network infrastructure security. An attacker with physical access to an affected device can achieve complete system compromise without requiring any network connectivity or prior authentication credentials. This allows for full control over network routing decisions, configuration changes, and potential lateral movement within the network. The vulnerability effectively neutralizes physical security measures and undermines the security posture of the entire SD-WAN infrastructure, as compromised devices can serve as entry points for broader network attacks.
Mitigation strategies for this vulnerability should focus on both physical and logical security controls. Organizations must implement strict physical access controls to prevent unauthorized individuals from interacting with network devices, including secure device placement and access monitoring. Cisco has released software updates to address this vulnerability, and organizations should immediately apply these patches to affected systems. The remediation process requires careful planning and execution to avoid service disruption, particularly in SD-WAN environments where device availability is critical for network operations. Additionally, implementing network segmentation and monitoring controls can help detect and prevent exploitation attempts even if physical security measures are bypassed.
This vulnerability aligns with CWE-287, which addresses improper authentication issues in software systems, and represents a specific instance where authentication mechanisms fail during the system initialization phase. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and initial access through physical presence, specifically targeting the boot process and system shell access. The vulnerability demonstrates how physical security gaps can be exploited to achieve remote code execution and full system compromise, highlighting the importance of considering all attack vectors including physical access points in security assessments and risk management strategies.