CVE-2024-21821: Arbitrary OS Command Execution Vulnerability in Multiple TP-LINK Products

Overview

In the rapidly evolving world of cybersecurity, it’s essential to stay abreast of the latest threats and vulnerabilities. One such vulnerability, identified as CVE-2024-21821, poses a significant threat to multiple TP-LINK products, allowing attackers to execute arbitrary OS commands. TP-LINK, a globally renowned provider of networking devices and accessories, is widely used in both personal and professional settings, making this vulnerability particularly concerning.
The vulnerability affects all network-adjacent authenticated users with access to the product from the LAN port or Wi-Fi. If exploited successfully, it could lead to potential system compromise or data leakage. As such, it’s crucial to be aware of this vulnerability, its impacts, and the measures needed to mitigate it.

Vulnerability Summary

CVE ID: CVE-2024-21821
Severity: High (CVSS Score 8.0)
Attack Vector: Network
Privileges Required: Low
User Interaction: Required
Impact: System compromise, Data leakage

Affected Products

Product | Affected Versions

TP-LINK AC1750 Wireless Dual Band Gigabit Router | All versions pre-patch
TP-LINK TL-WR940N N450 Wireless N Router | All versions pre-patch

How the Exploit Works

The exploit works by taking advantage of a flaw in the product’s network services that fail to properly sanitize user input. This vulnerability allows an authenticated attacker on the LAN or Wi-Fi to inject arbitrary OS commands into the system. These commands are then executed with high privileges, facilitating unauthorized actions that can lead to system compromise or data leakage.

Conceptual Example Code

To illustrate how the exploit might work, consider this conceptual example of an HTTP request that an attacker might send:

POST /cgi-bin/toolbox/commands.cgi HTTP/1.1
Host: tplink.router
Content-Type: application/x-www-form-urlencoded
cmd=ping&target=;cat /etc/passwd

In this example, the `cmd` parameter in the POST data is intended for a ping command, but the attacker has appended an additional command (`cat /etc/passwd`) after a semicolon. This is a common command injection technique. If the system does not sanitize this input, it would execute both the ping command and the subsequent command to display the contents of the `/etc/passwd` file, potentially exposing sensitive user data.