CVE-2021-1370 in IOS XR
Summary
by MITRE • 02/05/2021
A vulnerability in a CLI command of Cisco IOS XR Software for the Cisco 8000 Series Routers and Network Convergence System 540 Series Routers running NCS540L software images could allow an authenticated, local attacker to elevate their privilege to root. To exploit this vulnerability, an attacker would need to have a valid account on an affected device. The vulnerability is due to insufficient validation of command line arguments. An attacker could exploit this vulnerability by authenticating to the device and entering a crafted command at the prompt. A successful exploit could allow an attacker with low-level privileges to escalate their privilege level to root.
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Analysis
by VulDB Data Team • 02/24/2021
The vulnerability identified as CVE-2021-1370 represents a critical privilege escalation flaw within Cisco IOS XR Software affecting specific hardware platforms including the Cisco 8000 Series Routers and Network Convergence System 540 Series Routers. This vulnerability resides in the command line interface implementation and specifically targets the NCS540L software images. The flaw manifests when the system fails to properly validate command line arguments passed through the CLI, creating an avenue for malicious exploitation by authenticated users. The vulnerability is particularly concerning because it requires only a valid account on the device to exploit, making it accessible to attackers who have already gained some level of access to the system.
The technical nature of this vulnerability stems from inadequate input validation mechanisms within the CLI processing subsystem of the IOS XR software. When legitimate users execute commands through the command line interface, the system should perform thorough validation of all input parameters to prevent malicious code injection or command manipulation. However, in this case, the validation process is insufficient, allowing crafted command line arguments to bypass normal security controls. The vulnerability operates at the command execution level where an attacker can manipulate the CLI to execute unauthorized operations with elevated privileges. This flaw directly relates to CWE-20, which describes "Improper Input Validation" as a fundamental weakness in software design that can lead to various security issues including privilege escalation attacks.
The operational impact of CVE-2021-1370 is significant as it enables a local attacker with minimal privileges to achieve complete system compromise through a relatively simple exploitation technique. Once successfully exploited, the attacker gains root-level access to the router, providing them with unrestricted control over all network functions, configuration settings, and potentially access to sensitive network data. This privilege escalation capability allows the attacker to modify routing tables, disable security features, install malicious software, or extract confidential information from the network infrastructure. The vulnerability affects critical network infrastructure components that form the backbone of telecommunications networks, making the potential damage scale across entire network domains.
Mitigation strategies for this vulnerability should focus on immediate software updates and operational security measures. Cisco has released patches and software updates addressing this specific flaw, which should be deployed as a priority across all affected devices. Organizations should implement strict access controls limiting the number of accounts with CLI access and ensure that only authorized personnel have access to the affected systems. Network segmentation and monitoring solutions should be enhanced to detect anomalous CLI activity that might indicate exploitation attempts. Additionally, implementing principle of least privilege configurations and regular security audits can help reduce the attack surface and detect potential compromise attempts before they lead to successful privilege escalation. This vulnerability aligns with ATT&CK technique T1068, which covers "Exploitation for Privilege Escalation," and demonstrates how insufficient input validation can create opportunities for attackers to escalate their access privileges within network infrastructure systems.