Security researcher discovered thousands of Lantronix Serial-to-Ethernet devices connected online that leak Telnet passwords.

The security researcher Ankit Anubhav, principal researcher at NewSky Security, has discovered thousands of Serial-to-Ethernet devices connected online that leak Telnet passwords.

Hackers can use the leaked passwords to launch cyber attacks against the equipment that is connected to them.

Serial-to-Ethernet “device servers” are used by companies to connect to remote equipment that only exposed a serial interfaces.

The flawed Serial-to-Ethernet “device servers” are manufactured by the US vendor Lantronix.

The products UDS and xDirect easily allow to manage the devices via a LAN or WAN connection, such type of devices allows to easily implement Ethernet connectivity to virtually any device or machine with a serial interface. Users just need to connect the device RS-XXX serial connector to the product that exposes an RJ-45 Ethernet connector that can be used to control the device.

The “device servers” are widely adopted in to give connectivity to ICS (Industrial Control Systems), most of them are very old equipment that only comes with serial ports.

According to Ankit Anubhav, a half of Lantronix device servers are exposed online leaking their Telnet passwords. An attacker can take over the device via Telnet and use the privileged access to send serial commands to the connected devices.

“6,464 Lantronix device servers that may be connected to critical ICS-grade equipment are proudly exposing their passwords,” Anubhav told Bleeping Computer. “This accounts for 48% of the devices on Shodan.”

Imagine the potential dangers of a cyber attack against an ICS equipment exposed online through the vulnerable Lantronix device.

Anubhav explained that data exposure is an old flaw that could be exploited by attackers to retrieve the setup config of Lantronix devices by sending a malformed request on port 30718.

The Metaploit hacking platform includes a Lantronix “Telnet Password Recovery” module that could be exploited to retrieve the setup record from Lantronix serial-to-ethernet devices via the config port (30718/udp, enabled by default on old versions of Lantronix devices) and extracts the Telnet password in plain text.

Once again patch management is the root cause of the problem, vulnerable devices have not installed security updates to fix the issue.

Pierluigi Paganini

(Security Affairs – hacking, Serial-To-Ethernet devices)

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