Advantech – a maker of industrial PCs, embedded single board computers and automation controllers and software – has patched a critical vulnerability in its EKI-1200 series Modbus gateways that can be used by hackers to execute code.
According to Advantech, the EKI-1200 series Modbus gateways are bi-directional gateways for integrating new and existing Modbus/RTU and Modbus/ASCII serial devices to newer TCP/IP networked-based devices.
In an advisory, researchers at Core Security warned today that the EKI-1221D product is vulnerable to a buffer overflow that can be exploited by remote attackers to execute arbitrary code via a hardcoded root user credential and a specific query against a vulnerable CGI file.
“This vulnerability is caused by an incorrect manipulation of an input parameter of the file “index.cgi”,” the advisory notes. “When it receives at least 136 characters in the num variable it generates a segmentation fault, which means that it can be exploited in order to execute arbitrary code. The request must be done using the POST method in order to work. The CGI file may require authentication, and the webserver’s config file defines the localhost root user as the server admin.”
“Taking into account that the root user is hardcoded in the firmware, there is a chance that it could remain unchanged,” the advisory continues. “This user may work for authentication, the username is “root” and the password “ab6TRGT20sY26″.”
Andres Guillermo Blanco, senior researcher at Core Security, called the vulnerability highly severe, and noted that once a device has been attacked it could be used to pivot around and access internal networks, gather information or attack other devices. He added that Core Security is not aware of any attempts to exploit the vulnerability in the wild, and advises organizations not to connect the devices to the Internet.
“The vendor released a new version of the firmware that fixes the vulnerabilities,” according to the Core Security advisory. “[It’s] recommended that all the vulnerable users update their devices.”