CVE-2021-45558 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-2021-45558 represents a critical command injection flaw affecting multiple NETGEAR router models including RBK752, RBR750, RBS750, RBK852, RBR850, and RBS850. This vulnerability resides in the web-based management interface of these devices and allows authenticated attackers to execute arbitrary commands on the affected systems. The flaw stems from insufficient input validation and sanitization within the device's web server component, specifically in how it processes user-supplied parameters that are subsequently passed to system commands without proper escaping or filtering mechanisms. The affected firmware versions prior to 3.2.16.6 demonstrate a failure in implementing proper security controls that would prevent malicious command injection attempts.
The technical implementation of this vulnerability enables an authenticated user to manipulate input fields within the device's web interface to inject shell commands that are then executed with the privileges of the web server process. This typically occurs through parameters that control network settings, diagnostic functions, or other system operations where user input is directly incorporated into system command execution paths. The vulnerability is classified as a command injection weakness under CWE-77, which specifically addresses situations where untrusted data is used to construct operating system commands without proper validation or sanitization. The attack vector requires an attacker to first authenticate to the device using valid credentials, which reduces the attack surface but does not eliminate the severity of the impact.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with complete control over the affected network devices. Once exploited, the attacker can gain persistent access to the network infrastructure, potentially enabling them to redirect traffic, modify network configurations, intercept communications, or establish backdoors for continued access. The vulnerability affects enterprise and residential network environments where these routers serve as critical network gateways, potentially allowing attackers to compromise entire network segments. From an adversarial perspective, this vulnerability aligns with ATT&CK technique T1059.001 for Command and Scripting Interpreter, and T1021.001 for Remote Services, as it enables both local command execution and network service manipulation. The impact is particularly concerning because these devices often serve as the primary gateway for network traffic and may be configured with administrative credentials that are not regularly changed.
Mitigation strategies for CVE-2021-45558 primarily involve upgrading to the patched firmware versions 3.2.16.6 or later, which contain proper input validation and sanitization mechanisms. Network administrators should also implement additional security controls such as restricting administrative access to these devices, implementing network segmentation, and monitoring for unusual network traffic patterns that may indicate exploitation attempts. The vulnerability highlights the importance of proper input validation practices and demonstrates the critical need for firmware security updates in network infrastructure devices. Organizations should also consider implementing network access controls and firewall rules to limit access to administrative interfaces, particularly from untrusted networks. Regular vulnerability assessments and security audits of network infrastructure components are essential to identify and remediate similar weaknesses before they can be exploited by malicious actors.