CVE-2021-1336 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-2021-1336 represents a critical security flaw affecting multiple Cisco Small Business routers including RV016, RV042, RV042G, RV082, RV320, and RV325 models. This vulnerability stems from insufficient input validation mechanisms within the web-based management interface, creating a pathway for authenticated remote attackers to compromise the affected devices. The flaw specifically resides in how the system processes user-supplied input, failing to properly sanitize or validate data submitted through HTTP requests. According to the Common Weakness Enumeration catalog, this vulnerability maps to CWE-20, which describes "Improper Input Validation" as a fundamental weakness that allows malicious input to bypass security controls and potentially execute arbitrary code or cause system instability.
The technical exploitation of this vulnerability requires an attacker to possess valid administrator credentials for the affected device, establishing a baseline authentication requirement that reduces the attack surface but does not eliminate the risk entirely. Once authenticated, an attacker can craft specifically designed HTTP requests that leverage the improper input validation to execute arbitrary code with root privileges on the underlying operating system. This privilege escalation capability means that successful exploitation could result in complete system compromise, allowing attackers to gain full control over the router's functionality and potentially use it as a foothold for broader network infiltration. The vulnerability also presents a denial of service risk, where exploitation could cause the device to restart unexpectedly, disrupting network connectivity and potentially creating availability issues for network users.
From an operational impact perspective, these vulnerabilities pose significant risks to network security and availability in small business environments where these routers are commonly deployed. The combination of remote code execution capabilities and potential denial of service conditions creates multiple attack vectors that could be leveraged by threat actors for various malicious purposes. Network administrators face the challenge of maintaining secure access controls while ensuring operational continuity, as these vulnerabilities could be exploited to establish persistent access points within network infrastructure. The attack surface is particularly concerning given that these routers are typically deployed in small office environments where security monitoring may be limited, making exploitation more difficult to detect and respond to effectively.
Mitigation strategies for CVE-2021-1336 should prioritize immediate implementation of Cisco's security patches and firmware updates that address the input validation deficiencies in the web-based management interface. Network administrators should enforce strict access control measures, including regular credential rotation and multi-factor authentication where possible, to reduce the likelihood of unauthorized access. The vulnerability aligns with ATT&CK technique T1078 which covers valid accounts and privilege escalation, emphasizing the need for comprehensive access management practices. Additional defensive measures include implementing network segmentation to isolate critical infrastructure, deploying intrusion detection systems to monitor for suspicious HTTP traffic patterns, and conducting regular security assessments to identify and remediate similar vulnerabilities. Organizations should also consider network access controls that limit administrative access to these devices from trusted networks only, reducing the attack surface for remote exploitation attempts.