CVE-2019-15957 in Small Business RV Series Router
Summary
by MITRE
A vulnerability in the web-based management interface of certain Cisco Small Business RV Series Routers could allow an authenticated, remote attacker with administrative privileges to inject arbitrary commands into the underlying operating system. When processed, the commands will be executed with root privileges. The vulnerability is due to insufficient validation of user-supplied input. An attacker could exploit this vulnerability by providing malicious input to a specific field in the web-based management interface of an affected device. A successful exploit could allow the attacker to execute arbitrary commands on the underlying Linux operating system as the root user.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 09/23/2020
The vulnerability identified as CVE-2019-15957 represents a critical command injection flaw within the web-based management interface of Cisco Small Business RV Series Routers. This security weakness affects a range of enterprise-grade networking equipment that serves small to medium business environments, making it particularly concerning given the widespread deployment of these devices in corporate networks. The vulnerability exists within the router's web management portal, which provides administrators with a graphical interface to configure and manage network settings. Attackers who have already gained administrative access to the device can exploit this flaw to escalate their privileges and execute arbitrary commands with root-level permissions on the underlying Linux operating system.
The technical root cause of this vulnerability stems from insufficient input validation mechanisms within the affected web interface. Specifically, the system fails to properly sanitize or validate user-supplied input before processing it through the underlying operating system commands. This inadequate validation creates a command injection pathway where malicious input can be interpreted and executed as system commands rather than being treated as simple data. The vulnerability is classified under CWE-77 as a Command Injection flaw, which is a well-documented weakness in software security that allows attackers to execute arbitrary commands on a target system. The flaw is particularly dangerous because it requires only authenticated access to the web interface, meaning that an attacker who has already compromised administrative credentials can leverage this vulnerability to gain complete system control.
The operational impact of CVE-2019-15957 is severe and multifaceted, as it enables attackers to execute arbitrary code with the highest level of system privileges available. Once exploited, the vulnerability allows for complete compromise of the affected router, potentially enabling attackers to modify network configurations, redirect traffic, install backdoors, or exfiltrate sensitive network information. The root-level execution capability means that attackers can manipulate the underlying Linux operating system, access all network interfaces, modify firewall rules, and potentially use the compromised router as a pivot point to attack other systems within the network. This vulnerability directly aligns with ATT&CK technique T1059.001 for Command and Scripting Interpreter, where adversaries use legitimate system tools to execute commands, and T1068 for Exploitation for Privilege Escalation, as the attack leverages existing administrative access to escalate to root privileges.
Mitigation strategies for this vulnerability should prioritize immediate patching of affected devices through Cisco's security advisories and firmware updates. Organizations must also implement network segmentation and access controls to limit administrative access to these devices, ensuring that only authorized personnel can reach the web management interface. Additional defensive measures include monitoring network traffic for suspicious command execution patterns, implementing web application firewalls to detect and block malicious input, and conducting regular security assessments of network infrastructure. The vulnerability highlights the importance of input validation and proper sanitization practices in web applications, particularly those with elevated privileges. Security teams should also consider implementing principle of least privilege configurations and regular credential rotation to minimize the potential impact if administrative access is compromised. Given the nature of the vulnerability and its potential for lateral movement within networks, organizations should perform comprehensive network audits to identify all affected devices and ensure that proper security controls are in place to prevent exploitation.