CVE-2021-1211 in Small Business
Summary
by MITRE • 01/14/2021
Multiple vulnerabilities in the web-based management interface of Cisco Small Business RV110W, RV130, RV130W, and RV215W Routers could allow an authenticated, remote attacker to execute arbitrary code or cause an affected device to restart unexpectedly. The 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. Cisco has not released software updates that address these vulnerabilities.
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Analysis
by VulDB Data Team • 02/14/2021
The vulnerability identified as CVE-2021-1211 affects Cisco Small Business routers including the RV110W, RV130, RV130W, and RV215W models, representing a critical security flaw in their web-based management interfaces. This vulnerability stems from inadequate input validation mechanisms that fail to properly sanitize user-supplied data before processing within the router's operating system. The affected devices operate on embedded operating systems that are particularly susceptible to code injection attacks when faced with malformed input sequences, creating a pathway for malicious exploitation through the web administration portal that is commonly accessible to network administrators.
The technical exploitation of this vulnerability requires an attacker to possess valid administrator credentials, which establishes a baseline authentication requirement that reduces the attack surface but does not eliminate the risk entirely. Attackers can craft specifically designed HTTP requests that bypass normal input validation checks, allowing them to inject malicious payloads into the router's processing pipeline. These crafted requests leverage the improper input validation by sending sequences that the web interface does not adequately filter, potentially leading to command injection or buffer overflow conditions within the underlying operating system. The vulnerability's classification as a CWE-20 - Improper Input Validation directly aligns with the observed behavior where user-supplied data is not properly sanitized before being processed by the application's internal functions.
The operational impact of this vulnerability extends beyond simple code execution capabilities to include potential denial of service conditions that can render network infrastructure inaccessible to legitimate users. When successfully exploited, the vulnerability allows attackers to execute arbitrary code with root privileges, effectively providing complete control over the affected router's operations and potentially enabling further lateral movement within the network. The device restart functionality represents a particularly concerning aspect as it can be leveraged to create persistent denial of service attacks that disrupt network connectivity for extended periods. The lack of available software updates from Cisco creates a persistent risk for affected organizations that cannot immediately remediate the vulnerability through standard patch management procedures.
Organizations affected by this vulnerability should implement immediate mitigations including network segmentation to limit access to the router management interfaces, enforcing strict access controls and monitoring for unusual administrative activities, and considering temporary network isolation of affected devices until proper patches can be deployed. The vulnerability demonstrates the importance of proper input validation as outlined in the CWE catalog and aligns with ATT&CK techniques related to privilege escalation and command execution. Network administrators should also consider implementing intrusion detection systems that can identify suspicious HTTP request patterns and monitor for potential exploitation attempts targeting these specific router models. The absence of vendor-provided patches at the time of reporting highlights the critical need for organizations to maintain comprehensive vulnerability management processes and to consider alternative security controls when official remediations are not immediately available.