CVE-2020-3291 in RV016
Summary
by MITRE
Multiple vulnerabilities in the web-based management interface of Cisco Small Business RV320 and RV325 Series Routers and Cisco Small Business RV016, RV042, and RV082 Routers could allow an authenticated, remote attacker with administrative privileges to execute arbitrary code on an affected device. The vulnerabilities are due to insufficient boundary restrictions on user-supplied input to scripts in the web-based management interface. An attacker with administrative privileges that are sufficient to log in to the web-based management interface could exploit each vulnerability by sending crafted requests that contain overly large values to an affected device, causing a stack overflow. A successful exploit could allow the attacker to cause the device to crash or allow the attacker to execute arbitrary code with root privileges on the underlying operating system.
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Analysis
by VulDB Data Team • 10/25/2020
The vulnerability identified as CVE-2020-3291 affects Cisco Small Business routers in the RV320 and RV325 series as well as the RV016, RV042, and RV082 models. This represents a critical security flaw in the web-based management interface that could be exploited by authenticated attackers who have administrative privileges. The vulnerability stems from inadequate input validation mechanisms within the router's web interface scripts, specifically failing to properly enforce boundary restrictions on user-supplied data. This weakness creates a pathway for attackers to manipulate the system through carefully crafted requests that contain excessively large values designed to trigger memory corruption issues.
The technical implementation of this vulnerability involves stack overflow conditions that occur when the affected routers process user input without proper sanitization or size limitations. When an authenticated administrator sends maliciously formatted requests containing oversized parameters to the web interface, the system's memory management routines become compromised. This type of vulnerability falls under the CWE-121 category of Stack-based Buffer Overflow, where insufficient boundary checking allows attackers to overwrite stack memory locations. The exploitation mechanism leverages the fact that the web interface scripts do not validate the size or content of incoming parameters before processing them, creating a predictable crash condition that can be manipulated to execute arbitrary code.
The operational impact of this vulnerability is severe as it provides attackers with complete system compromise capabilities. Once successfully exploited, the attacker gains root privileges on the underlying operating system, enabling full control over the router's functions including network traffic manipulation, configuration changes, and potential use as a pivot point for further attacks within the network. The attack requires only administrative login credentials, making it particularly dangerous as it can be exploited by insiders or compromised accounts. The potential for denial of service through device crashes, combined with the ability to execute arbitrary code, creates a dual threat that could disrupt network operations while simultaneously providing persistent access for malicious actors.
Mitigation strategies for CVE-2020-3291 should prioritize immediate firmware updates from Cisco to address the identified input validation flaws. Organizations should implement network segmentation to limit access to router management interfaces, ensuring that only authorized personnel have administrative privileges. Additional protective measures include disabling unnecessary web management interfaces, implementing strong authentication controls, and monitoring for unusual administrative activities. The vulnerability aligns with ATT&CK technique T1059.007 for command and script injection, as well as T1068 for exploit for privilege escalation. Regular security assessments and network monitoring should be conducted to detect potential exploitation attempts, while access controls should be strictly enforced to minimize the attack surface available to potential adversaries.