As uncovered by researchers on ProCheckUp/SafeScan - GitHub , the telnet password can often be found within the Config.cfg file, which is accessible via the device web interface's backup function.
This platform runs a Linux operating system, typically with kernel version 3.0.8, designed for MIPS architecture. Key specifications include:
ZKTeco periodically releases firmware patches that change default credential behaviors or disable insecure legacy protocols like Telnet by default.
Block all outbound internet access from the security VLAN to prevent compromised devices from communicating with external Command and Control (C2) servers. Summary Checklist for Administrators Action Item Scan subnet for open Port 23 connections. Test Attempt login using standard legacy default keys. Remediate Execute passwd root or patch /etc/passwd file. Verify Reboot device and confirm the old default password fails. Harden
Newer production runs assign a unique root password to each physical unit. This password is often cryptographically derived from the device’s unique MAC address or hardware serial number, preventing universal credential attacks. 2. Disabling Telnet by Default
Save the file and reboot the hardware. Perform a follow-up port scan to guarantee port 23 remains closed. 2. Upgrading to Secure Firmware Branches
Many embedded architectures mount the root filesystem as read-only to protect firmware stability. If you attempt to change the password on a read-only filesystem, the system will return a write error. Check the mount status or proactively remount the file system with read-write permissions: mount -o remount,rw / Use code with caution. Step 3: Execute the Password Command
Updating the default password is only the first layer of defense. To fully protect biometric endpoints, network engineers should implement the following security measures:
If you're using a standard admin account:
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Leaving the default Telnet configuration untouched exposes the device to several severe vectors of exploitation:
The 2025 security initiative introduced significant improvements that are for ZMM200-220-210 platforms. Administrators should:
Isolate all ZMM220 devices within a dedicated, non-routable Security VLAN.
