CVE-2023-1389 in Archer AX21
Summary
by MITRE • 03/16/2023
TP-Link Archer AX21 (AX1800) firmware versions before 1.1.4 Build 20230219 contained a command injection vulnerability in the country form of the /cgi-bin/luci;stok=/locale endpoint on the web management interface. Specifically, the country parameter of the write operation was not sanitized before being used in a call to popen(), allowing an unauthenticated attacker to inject commands, which would be run as root, with a simple POST request.
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Analysis
by VulDB Data Team • 03/14/2025
The CVE-2023-1389 vulnerability represents a critical command injection flaw in TP-Link Archer AX21 wireless routers running firmware versions prior to 1.1.4 build 20230219. This vulnerability exists within the web management interface of the device, specifically targeting the country form parameter of the /cgi-bin/luci;stok=/locale endpoint. The flaw demonstrates a classic lack of input validation and sanitization that enables arbitrary code execution with elevated privileges. The vulnerability is particularly concerning as it allows unauthenticated attackers to exploit the device without requiring any credentials, making it accessible to anyone who can reach the router's web interface.
The technical implementation of this vulnerability stems from improper handling of user-supplied input within the web application's backend processing. When the country parameter is submitted through a POST request to the affected endpoint, the firmware fails to sanitize this input before incorporating it into a system call via the popen() function. This creates a direct command injection vector where attacker-controlled input can be executed as shell commands with root privileges. The popen() function in C programming language executes shell commands and returns a file pointer to the command output, making it a prime target for command injection attacks when combined with unsanitized user input. This vulnerability aligns with CWE-77 and CWE-78 classifications, which specifically address command injection flaws and improper neutralization of special elements used in OS commands.
The operational impact of this vulnerability is severe and multifaceted, as it provides complete remote control over the affected devices. An attacker can execute arbitrary commands with root privileges, potentially leading to full system compromise, data exfiltration, or the installation of persistent backdoors. The unauthenticated nature of the exploit means that attackers can gain access without any prior credentials, making the vulnerability particularly dangerous in network environments where routers are accessible from external networks. The affected Archer AX21 routers, which are commonly deployed in residential and small office environments, could become part of botnets or be used as stepping stones for further network reconnaissance and attacks. This vulnerability also represents a significant risk to network security posture as it allows attackers to modify router configurations, redirect traffic, or establish persistent access points within the network.
Mitigation strategies for this vulnerability should include immediate firmware updates to version 1.1.4 or later, which address the input sanitization issues in the web management interface. Network administrators should also implement network segmentation to isolate critical devices from less secure network segments, and consider disabling remote management access to router interfaces when not actively required. Additional protective measures include monitoring network traffic for suspicious POST requests to the affected endpoint, implementing web application firewalls to detect and block malicious payloads, and conducting regular vulnerability assessments of network infrastructure. From an ATT&CK framework perspective, this vulnerability maps to techniques involving command and control communications, privilege escalation, and remote service exploitation, making it a critical target for both defensive and offensive security teams to address promptly.