CVE-2021-1512 in SD-WAN
Summary
by MITRE • 05/06/2021
A vulnerability in the CLI of Cisco SD-WAN Software could allow an authenticated, local attacker to overwrite arbitrary files in the underlying file system of an affected system. This vulnerability is due to insufficient validation of the user-supplied input parameters of a specific CLI command. An attacker could exploit this vulnerability by issuing that command with specific parameters. A successful exploit could allow the attacker to overwrite the content in any arbitrary files that reside on the underlying host file system.
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Analysis
by VulDB Data Team • 05/09/2021
The vulnerability identified as CVE-2021-1512 represents a critical local privilege escalation flaw within Cisco SD-WAN Software command-line interface. This weakness stems from inadequate input validation mechanisms that fail to properly sanitize user-supplied parameters within a specific CLI command. The vulnerability affects systems running Cisco SD-WAN software where authenticated local users can leverage this flaw to execute arbitrary file overwrite operations on the underlying host file system. The flaw exists at the interface level where command processing does not sufficiently validate the integrity and legitimacy of user inputs before executing file system operations, creating a pathway for malicious file manipulation.
The technical exploitation of this vulnerability requires an authenticated local attacker who possesses valid credentials to access the affected system's command-line interface. Once authenticated, the attacker can invoke the specific vulnerable CLI command with crafted parameters that bypass normal file system access controls. The insufficient input validation allows the attacker to specify arbitrary file paths that the system will attempt to overwrite, potentially targeting critical system files, configuration files, or even executable components. This vulnerability falls under CWE-20, which categorizes improper input validation as a fundamental weakness in software design that enables various attack vectors including path traversal and file manipulation exploits.
The operational impact of CVE-2021-1512 extends beyond simple file overwriting capabilities, as it provides attackers with the potential to compromise the integrity and availability of the entire SD-WAN infrastructure. An attacker could overwrite critical system files, configuration databases, or even replace legitimate binaries with malicious alternatives, leading to complete system compromise and potential network disruption. The vulnerability's local nature means that attackers must already have authenticated access to the system, but this access requirement significantly reduces the attack surface while still presenting a substantial risk to organizations with compromised local accounts or insider threats. The exploitability factor is enhanced by the fact that the vulnerability does not require elevated privileges beyond authentication, making it particularly dangerous in environments where local access is not adequately restricted.
Organizations should implement immediate mitigations including restricting local access to administrative accounts, implementing strict access controls for CLI interfaces, and conducting comprehensive audits of system file integrity. Network segmentation and privileged access management solutions can help limit the potential impact of local privilege escalation attacks. Regular security assessments and monitoring for unauthorized CLI usage should be implemented as part of the overall security posture. The vulnerability aligns with ATT&CK technique T1068, which covers local privilege escalation, and represents a significant risk to enterprise network security when combined with other attack vectors. System administrators should also consider implementing file integrity monitoring solutions that can detect unauthorized file modifications and alert security teams to potential exploitation attempts. The remediation process requires applying official Cisco patches and updates while maintaining comprehensive logging of CLI activities to detect potential exploitation attempts.