CVE-2021-25310 in Linksys WRT160NL
Summary
by MITRE • 02/02/2021
The administration web interface on Belkin Linksys WRT160NL 1.0.04.002_US_20130619 devices allows remote authenticated attackers to execute system commands with root privileges via shell metacharacters in the ui_language POST parameter to the apply.cgi form endpoint. This occurs in do_upgrade_post in mini_httpd. NOTE: This vulnerability only affects products that are no longer supported by the maintaine
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Analysis
by VulDB Data Team • 06/04/2024
The vulnerability identified as CVE-2021-25310 represents a critical remote command execution flaw affecting Belkin Linksys WRT160NL routers running firmware version 1.0.04.002_US_20130619. This issue resides within the administration web interface of the device and demonstrates a classic improper input validation vulnerability that allows attackers to escalate privileges and execute arbitrary system commands with root level access. The vulnerability specifically manifests when the ui_language parameter is submitted through the apply.cgi form endpoint, which is processed by the mini_httpd web server component. This flaw falls under the CWE-77 category, which encompasses command injection vulnerabilities where user-supplied data is directly incorporated into system commands without proper sanitization or validation.
The technical exploitation of this vulnerability occurs through the manipulation of the ui_language POST parameter within the apply.cgi endpoint, which is processed by the do_upgrade_post function in the mini_httpd web server. When an authenticated attacker submits malicious shell metacharacters through this parameter, the system fails to properly sanitize the input before incorporating it into system commands, creating an opportunity for arbitrary code execution. The vulnerability is particularly concerning because it allows remote authenticated attackers to execute commands with root privileges, effectively providing complete system compromise. This type of vulnerability aligns with ATT&CK technique T1059.001, which covers command and scripting interpreter execution, and T1068, which involves exploit for privilege escalation.
The operational impact of this vulnerability extends beyond simple remote code execution to encompass complete system compromise and potential network infiltration. An attacker who successfully exploits this vulnerability gains root-level access to the router, enabling them to modify network configurations, install malicious software, monitor network traffic, and potentially use the compromised device as a pivot point for attacking other systems within the network. The affected WRT160NL devices are particularly vulnerable because they are no longer supported by the manufacturer, meaning no security patches or updates are available to address this flaw. This leaves users exposed to potential exploitation for an extended period, as the device has reached end-of-life status and no longer receives security maintenance. The vulnerability demonstrates how legacy network equipment, particularly consumer-grade routers, often contain unpatched security flaws that persist long after their initial deployment, creating ongoing security risks for organizations and individuals who continue to use these devices. Organizations should implement immediate network segmentation and monitoring to detect potential exploitation attempts, while also planning for device replacement to eliminate this exposure vector. The issue underscores the importance of maintaining up-to-date network infrastructure and avoiding the use of unsupported devices in production environments, as these often serve as persistent attack vectors for threat actors.