CVE-2021-45561 in RBK752
Summary
by MITRE • 12/26/2021
Certain NETGEAR devices are affected by command injection by an authenticated user. This affects RBK752 before 3.2.16.6, RBR750 before 3.2.16.6, RBS750 before 3.2.16.6, RBK852 before 3.2.16.6, RBR850 before 3.2.16.6, and RBS850 before 3.2.16.6.
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Analysis
by VulDB Data Team • 12/28/2021
The vulnerability CVE-2021-45561 represents a critical command injection flaw affecting multiple NETGEAR router models within the RBK and RBR series. This security weakness allows authenticated attackers to execute arbitrary commands on affected devices, potentially compromising the entire network infrastructure. The vulnerability specifically impacts devices running firmware versions prior to 3.2.16.6, including RBK752, RBR750, RBS750, RBK852, RBR850, and RBS850 models. The flaw stems from inadequate input validation and sanitization within the device's web interface, creating an exploitable path for malicious command execution.
This vulnerability falls under CWE-77 which specifically addresses command injection flaws in software systems. The technical implementation of the flaw involves the improper handling of user-supplied input within the device's administrative interface. When authenticated users submit crafted input through web forms or API endpoints, the system fails to properly sanitize or validate the data before incorporating it into system commands. This allows attackers to inject malicious commands that execute with the privileges of the web server process, typically running with elevated system permissions. The vulnerability is particularly dangerous because it requires only authentication, making it accessible to users with legitimate access credentials.
The operational impact of this vulnerability extends beyond simple privilege escalation, potentially enabling complete network compromise. An authenticated attacker could leverage this flaw to gain persistent access to the affected routers, modify network configurations, redirect traffic, or establish backdoors for future access. The attack surface is significant as these devices often serve as primary network gateways, making them attractive targets for attackers seeking to maintain long-term access to enterprise or residential networks. Network reconnaissance activities could be conducted through the compromised devices, and the vulnerability could facilitate lateral movement within network segments. Additionally, the compromised devices could be used as command and control nodes for distributed denial of service attacks or other malicious activities.
Mitigation strategies for CVE-2021-45561 should prioritize immediate firmware updates to versions 3.2.16.6 or later, which contain the necessary patches to address the command injection vulnerability. Network administrators should implement strict access controls and regularly audit user permissions to minimize the attack surface. The principle of least privilege should be enforced, ensuring that only authorized personnel have administrative access to network devices. Network segmentation and monitoring solutions should be deployed to detect anomalous behavior that might indicate exploitation attempts. Security teams should also consider implementing network access control policies that restrict administrative access to these devices from untrusted networks. Regular vulnerability assessments and penetration testing should be conducted to identify similar weaknesses in other network infrastructure components. The ATT&CK framework categorizes this vulnerability under T1059.001 for command and scripting interpreter, highlighting the need for comprehensive endpoint protection and monitoring solutions. Organizations should also establish incident response procedures specifically addressing network device compromise scenarios, as the impact of such vulnerabilities can extend far beyond the immediate device.