CVE-2021-1383 in IOS XE SD-WAN
Summary
by MITRE • 03/25/2021
Multiple vulnerabilities in the CLI of Cisco IOS XE SD-WAN Software could allow an authenticated, local attacker to access the underlying operating system with root privileges. These vulnerabilities are due to insufficient input validation of certain CLI commands. An attacker could exploit these vulnerabilities by authenticating to the device and submitting crafted input to the CLI. The attacker must be authenticated as an administrative user to execute the affected commands. A successful exploit could allow the attacker to access the underlying operating system with root privileges.
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Analysis
by VulDB Data Team • 04/04/2021
The vulnerability identified as CVE-2021-1383 represents a critical privilege escalation flaw within Cisco IOS XE SD-WAN Software that directly undermines the security posture of network infrastructure devices. This vulnerability specifically targets the command line interface component of the software, which serves as the primary administrative interface for network device management. The flaw stems from inadequate input validation mechanisms that fail to properly sanitize user-supplied data before processing. According to the CWE (Common Weakness Enumeration) classification, this vulnerability maps to CWE-20, which describes "Improper Input Validation," a fundamental weakness that allows malicious inputs to bypass security controls and potentially execute unauthorized operations. The affected software components reside within the underlying operating system of the device, making this a particularly dangerous vulnerability as it provides direct pathways to system-level access.
The technical exploitation of CVE-2021-1383 requires an attacker to first establish authentication credentials with administrative privileges, which significantly reduces the attack surface compared to remote vulnerabilities. However, this prerequisite does not diminish the severity of the flaw, as administrative accounts are often targeted in sophisticated attacks and may be compromised through various means such as credential theft, social engineering, or exploitation of other vulnerabilities. The vulnerability manifests when authenticated administrative users submit crafted input to specific CLI commands that do not properly validate the input parameters. This insufficient validation creates opportunities for command injection or other forms of code execution that can escalate privileges to root level access. The underlying operating system access gained through successful exploitation provides attackers with complete control over the device, enabling them to modify configurations, extract sensitive data, install malicious software, or establish persistence mechanisms.
From an operational impact perspective, the exploitation of CVE-2021-1383 can result in catastrophic consequences for network security and business continuity. Network administrators who rely on Cisco IOS XE SD-WAN devices for critical infrastructure management face the risk of complete system compromise, potentially affecting thousands of network endpoints and services. The vulnerability enables attackers to bypass traditional security controls and gain access to sensitive network information, including configuration details, network topology data, and potentially user credentials stored on the device. This access can facilitate lateral movement within the network, allowing attackers to escalate their privileges across multiple devices and potentially compromise the entire network infrastructure. The attack vector aligns with ATT&CK techniques categorized under privilege escalation and defense evasion, specifically leveraging T1068 (Local Port Forwarding) and T1059 (Command and Scripting Interpreter) to maintain persistent access and execute malicious commands.
Organizations should implement immediate mitigations to address CVE-2021-1383 by applying the relevant security patches provided by Cisco, which typically include enhanced input validation mechanisms and command sanitization routines. Network segmentation strategies should be reinforced to limit the potential impact of compromised administrative accounts, while implementing strict access controls and monitoring for unusual CLI activities. Security teams should conduct comprehensive vulnerability assessments to identify all affected devices and ensure proper patch management processes are in place. Additionally, implementing behavioral analytics and anomaly detection systems can help identify potential exploitation attempts by monitoring for unusual administrative command patterns or unauthorized access attempts. The vulnerability serves as a reminder of the critical importance of input validation in security-critical applications and highlights the necessity of robust security controls even within trusted administrative environments. Regular security audits and penetration testing should be conducted to identify similar weaknesses in other network components and ensure comprehensive protection against privilege escalation attacks.