CVE-2021-1335 in RV016
Summary
by MITRE • 02/05/2021
Multiple vulnerabilities in the web-based management interface of Cisco Small Business RV016, RV042, RV042G, RV082, RV320, and RV325 Routers could allow an authenticated, remote attacker to execute arbitrary code or cause an affected device to restart unexpectedly. These vulnerabilities are due to improper validation of user-supplied input in the web-based management interface. An attacker could exploit these vulnerabilities by sending crafted HTTP requests to an affected device. A successful exploit could allow the attacker to execute arbitrary code as the root user on the underlying operating system or cause the device to reload, resulting in a denial of service (DoS) condition. To exploit these vulnerabilities, an attacker would need to have valid administrator credentials on the affected device.
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Analysis
by VulDB Data Team • 02/24/2021
The vulnerability identified as CVE-2021-1335 represents a critical security flaw affecting multiple Cisco Small Business routers including the RV016, RV042, RV042G, RV082, RV320, and RV325 models. This vulnerability resides within the web-based management interface of these devices, creating a pathway for authenticated remote attackers to gain elevated privileges and execute malicious code. The flaw stems from inadequate input validation mechanisms that fail to properly sanitize user-supplied data, allowing attackers to manipulate the system through crafted HTTP requests. According to the CWE taxonomy, this vulnerability maps to CWE-20, which describes "Improper Input Validation" as a fundamental weakness that enables various injection attacks and privilege escalation scenarios. The attack vector requires an attacker to possess valid administrator credentials, making this a privilege escalation vulnerability rather than a purely remote code execution flaw.
The technical implementation of this vulnerability allows an authenticated attacker to manipulate the router's web interface by submitting specially crafted HTTP requests that bypass normal input validation checks. When the device processes these malformed requests, it fails to properly validate the user input, leading to potential buffer overflows, command injection, or other code execution scenarios. The exploitation mechanism operates at the application layer where the web interface fails to properly sanitize parameters before processing them within the underlying operating system. This creates a direct path for attackers to execute arbitrary commands with root privileges, effectively compromising the entire device. The vulnerability's impact extends beyond code execution to include denial of service conditions, as successful exploitation can cause the device to restart unexpectedly, disrupting network connectivity and potentially leading to extended outages.
From an operational perspective, the implications of CVE-2021-1335 are severe for organizations relying on these routers for network infrastructure. The requirement for valid administrator credentials means that the vulnerability cannot be exploited by external attackers without prior compromise of administrative accounts, but this still represents a significant risk in environments where credential security is not properly enforced. The attack surface is particularly concerning for small business networks where administrative access may be less strictly controlled compared to enterprise environments. Network administrators face the challenge of identifying potentially compromised devices within their infrastructure, as the exploitation may not immediately trigger obvious alerts or logs. The vulnerability's presence in multiple router models suggests a systemic issue within Cisco's web interface implementation, potentially affecting hundreds or thousands of devices across various organizations.
Organizations should implement immediate mitigations including updating to the latest firmware versions released by Cisco to address the input validation flaws. Network segmentation and access control measures should be strengthened to limit administrative access to these devices, ensuring that only authorized personnel have the necessary credentials. Regular security audits and monitoring of administrative access logs can help detect potential exploitation attempts. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically targeting the 'Exploitation for Privilege Escalation' tactic. Security teams should also consider implementing network monitoring solutions that can detect unusual traffic patterns or HTTP request structures that might indicate exploitation attempts. Additionally, organizations should review and enforce strong credential management policies, including regular password changes and multi-factor authentication for administrative access to network devices. The vulnerability underscores the importance of maintaining up-to-date firmware across all network infrastructure components and demonstrates how seemingly minor input validation flaws can create significant security risks when combined with authenticated access.