CVE-2021-45596 in CBR750
Summary
by MITRE • 12/26/2021
Certain NETGEAR devices are affected by command injection by an authenticated user. This affects CBR750 before 4.6.3.6, RBK752 before 3.2.17.12, RBR750 before 3.2.17.12, RBS750 before 3.2.17.12, RBK852 before 3.2.17.12, RBR850 before 3.2.17.12, and RBS850 before 3.2.17.12.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 12/28/2021
The vulnerability CVE-2021-45596 represents a critical command injection flaw affecting multiple NETGEAR router models within the CBR750, RBK752, RBR750, RBS750, RBK852, RBR850, and RBS850 device families. This security weakness allows authenticated attackers with access to the device management interface to execute arbitrary commands on the underlying operating system. The vulnerability stems from insufficient input validation and sanitization within the web-based administration interface, where user-supplied parameters are directly incorporated into system commands without proper escaping or filtering mechanisms. This flaw particularly impacts devices running firmware versions prior to the specified patches, creating a significant attack surface for malicious actors who have gained legitimate access to the device's administrative interface.
The technical implementation of this vulnerability aligns with CWE-77 and CWE-94, which respectively address improper neutralization of special elements used in OS commands and improper control of generation of code. Attackers can exploit this weakness by crafting malicious input within specific web forms or API endpoints that handle configuration parameters, system commands, or network settings. When the device processes these inputs, the unfiltered user data gets concatenated with system command strings, enabling arbitrary code execution with the privileges of the web server process. The authenticated nature of this vulnerability means that attackers must first obtain valid credentials to access the device's administrative interface, but once inside, they can escalate their privileges to execute system-level commands including shell access, file manipulation, and network reconnaissance.
From an operational perspective, the impact of CVE-2021-45596 extends beyond simple privilege escalation as it enables attackers to completely compromise the affected devices. This vulnerability can be leveraged to establish persistent backdoors, redirect network traffic, modify firewall rules, or even install malicious firmware updates. The affected devices typically serve as network gateways and routers, making them prime targets for attackers seeking to establish command and control infrastructure or conduct man-in-the-middle attacks against network traffic. The vulnerability's presence in multiple device models suggests a systemic flaw in the firmware development process, potentially indicating inadequate security testing or code review practices during the software development lifecycle. Organizations with these devices deployed in production environments face significant risk of network infiltration, data exfiltration, and potential lateral movement within their infrastructure.
Mitigation strategies for CVE-2021-45596 should prioritize immediate firmware updates from NETGEAR to versions 4.6.3.6 and 3.2.17.12 or later for the affected device families. Network administrators should also implement strict access controls and authentication measures to limit administrative access to these devices, including multi-factor authentication and role-based access controls. The principle of least privilege should be enforced by restricting administrative access to only necessary personnel and implementing network segmentation to isolate critical devices. Additionally, organizations should conduct comprehensive vulnerability assessments of their network infrastructure to identify any other potentially affected devices and implement network monitoring solutions to detect anomalous behavior indicative of exploitation attempts. According to ATT&CK framework, this vulnerability maps to T1059.001 (Command and Scripting Interpreter: PowerShell) and T1068 (Exploitation for Privilege Escalation) techniques, making it a significant concern for defensive cybersecurity operations. Regular security audits and penetration testing should be conducted to ensure that all network devices remain patched and properly configured to prevent exploitation of similar vulnerabilities in the future.