CVE-2020-3602 in StarOS
Summary
by MITRE • 10/08/2020
A vulnerability in the CLI of Cisco StarOS operating system for Cisco ASR 5000 Series Routers could allow an authenticated, local attacker to elevate privileges on an affected device. The vulnerability is due to insufficient input validation of CLI commands. An attacker could exploit this vulnerability by sending crafted commands to the CLI. A successful exploit could allow the attacker to execute arbitrary code with the privileges of the root user on the affected device. To exploit this vulnerability, an attacker would need to have valid credentials on an affected device and know the password for the cli test-commands command.
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Analysis
by VulDB Data Team • 11/17/2020
The vulnerability identified as CVE-2020-3602 affects the Cisco StarOS operating system running on Cisco ASR 5000 Series Routers, representing a critical privilege escalation flaw that undermines the security posture of these network infrastructure devices. This vulnerability resides within the command-line interface implementation and demonstrates a fundamental failure in input validation controls that directly enables unauthorized privilege elevation. The issue specifically targets the cli test-commands functionality where insufficient sanitization of user inputs creates a pathway for malicious command injection attacks.
The technical exploitation of this vulnerability requires an authenticated local attacker who possesses valid credentials for the affected device along with knowledge of the specific cli test-commands password. This dual requirement for authentication and password knowledge places the vulnerability in the context of insider threat scenarios or compromised accounts rather than purely external attack vectors. The flaw manifests through improper validation of CLI command inputs, allowing an attacker to craft malicious commands that bypass normal access controls and execute with root privileges. This represents a classic command injection vulnerability pattern that aligns with CWE-77 and CWE-89 classifications, where inadequate input sanitization enables arbitrary code execution through command-line interfaces.
The operational impact of this vulnerability extends beyond simple privilege escalation to encompass complete system compromise of affected ASR 5000 Series routers. Once exploited, attackers gain root-level access to the underlying StarOS operating system, enabling them to modify system configurations, install backdoors, exfiltrate sensitive data, or disrupt network services. The vulnerability affects critical network infrastructure components that typically serve as core routing and switching points in telecommunications networks, making the potential impact substantial for organizations relying on these devices for network operations. This privilege escalation capability directly maps to ATT&CK technique T1068 which focuses on local privilege escalation through command injection vulnerabilities.
Mitigation strategies for CVE-2020-3602 should prioritize immediate implementation of Cisco's security advisories and firmware updates that address the input validation deficiencies in the CLI implementation. Network administrators must enforce strict access controls and credential management practices to minimize the risk of unauthorized access to affected devices, including regular credential rotation and principle of least privilege enforcement. Additional defensive measures include implementing network segmentation to limit lateral movement, deploying intrusion detection systems to monitor for suspicious CLI activity, and conducting regular security audits of router configurations. The vulnerability highlights the importance of comprehensive input validation across all user-facing interfaces and underscores the critical need for proper privilege separation in network operating systems. Organizations should also consider implementing privileged access management solutions and maintaining detailed audit logs of CLI activities to detect potential exploitation attempts. Given the severity of the privilege escalation capability, immediate patching and access control hardening represents the most effective response to prevent exploitation of this vulnerability in production environments.