CVE-2021-28151 in H8922
Summary
by MITRE • 05/07/2021
Hongdian H8922 3.0.5 devices allow OS command injection via shell metacharacters into the ip-address (aka Destination) field to the tools.cgi ping command, which is accessible with the username guest and password guest.
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Analysis
by VulDB Data Team • 05/12/2021
The vulnerability identified as CVE-2021-28151 affects Hongdian H8922 network devices running firmware version 3.0.5, representing a critical operating system command injection flaw that can be exploited by unauthorized attackers. This vulnerability resides within the web interface of the device where the tools.cgi ping command processes user input without proper sanitization. The specific attack vector involves the ip-address field, also known as the Destination field, which accepts shell metacharacters that get executed as operating system commands. The device authentication mechanism is particularly weak as it allows access using default credentials guest/guest, making the exploitation accessible to anyone with basic network connectivity and minimal technical knowledge.
This command injection vulnerability stems from inadequate input validation and sanitization within the web application layer of the device. When a user enters malicious shell metacharacters into the ip-address field and submits the ping request, the system fails to properly escape or filter these special characters before passing them to the underlying operating system shell. The flaw allows attackers to execute arbitrary commands with the privileges of the web server process, which typically runs with elevated permissions on the device. According to CWE-77, this represents a classic command injection vulnerability where user-supplied data flows directly into a command that is executed by the system shell without proper sanitization or context-aware escaping mechanisms.
The operational impact of this vulnerability is severe as it provides attackers with full command execution capabilities on the affected device. An attacker could potentially gain access to sensitive system information, modify device configurations, install malicious software, or use the device as a pivot point for further attacks within the network. The default guest credentials create an additional risk factor since many network administrators fail to change these default settings, leaving devices exposed to automated scanning and exploitation attempts. The vulnerability affects network infrastructure devices that are often overlooked in security assessments, creating potential entry points for lateral movement and persistent access within corporate networks. This aligns with ATT&CK technique T1059.001 for command and scripting interpreter and T1078.004 for valid accounts, as the exploitation leverages both command injection capabilities and default credential usage.
Mitigation strategies for CVE-2021-28151 should prioritize immediate credential changes and network segmentation to limit exposure. Organizations must ensure that all default accounts are disabled or have strong, unique passwords assigned to prevent unauthorized access. The most effective remediation involves implementing proper input validation and sanitization within the web application to prevent shell metacharacters from being processed as commands. Network administrators should also consider disabling unnecessary web services and implementing firewall rules to restrict access to the device management interfaces. The vulnerability demonstrates the importance of secure coding practices and input validation as outlined in OWASP Top Ten and NIST SP 800-53 security controls. Regular firmware updates and vulnerability assessments should be implemented as part of comprehensive security operations to prevent similar issues from being introduced in future device deployments. Additionally, network monitoring should be enhanced to detect suspicious ping command usage patterns that might indicate exploitation attempts.