USB-borne malware continues to present a major threat to industrial control systems (ICS) nearly a decade after the Stuxnet attacks on Iran's nuclear infrastructure first highlighted the danger.
This week Symantec unveiled a new product it says is designed to help organizations in critical infrastructure sectors better manage the threat.
The security vendor's new Industrial Control System Protection Neural (ICSP Neural) is a rugged USB scanning station that ICS operators can install in their environments for vetting the security of USB devices before the devices are inserted into a critical control system.
The scanner uses data from Symantec's threat intelligence network to look for malware and risky files on USB memory sticks. It features a light sandbox for running scripts, files, and other executables on USB devices to check for malware.
ICSP supports file reputation scans and a self-learning capability that Symantec says allows the scanner to identify, with a high degree of precision, not just known malware threats but also ones that are previously unknown. Devices with malware are cleaned and electronically "watermarked" as safe with a small, signed file.
ICSP includes an optional enforcement driver that organizations can install on workstations and other OT systems if they choose. The relatively lightweight driver — with less than a 5 MB footprint — ensures only USBs that have been scanned and watermarked as safe are allowed to mount on a target system.
The driver can currently be installed on OT systems running Windows XP to Windows 10. It works with workstations and human machine interface (HMI) systems from a variety of vendors, including Emerson and Rockwell. Symantec plans to introduce support for Linux systems sometime next year.
Symantec's new technology is similar to a tool that ICS vendor Honeywell introduced in 2017 called Secure Media Exchange (SMX). Like ICSP, Honeywell's SMX is designed to help operations and plant managers protect control systems against USB-borne malware threats, especially those targeted at OT environments and therefore not easily detected by standard antivirus tools.
Employees in industrial settings simply insert their removable media into SMX while checking in and checking out, so any malware on them can be detected and removed. As with ICSP Neural, plant managers can use the Honeywell appliance to prevent unchecked USB devices from using USB ports on critical systems.
ICSP addresses an important need for ICS operators, says Kunal Agarwal, general manager of IoT at Symantec.
Because of how critical they are, many ICS environments are typically air-gapped — inaccessible via network from the outside. In these situations, USB devices are critical to delivering software updates, files, patches, configuration changes, and other data to ICSes, Agarwal says. Often these devices represent the only way to provide ongoing updates and maintenance to critical systems, even though a high percentage of them contain malware and other threats, he says.
Honeywell recently analyzed data collected from 50 organizations in four sectors — oil and gas, energy, chemical, and paper and pulp — that are using SMX. The data showed 44% of the organizations had detected and blocked at least one suspicious file on a USB device.
Of the threats that were blocked, 26% had the potential to create a major disruption — such as loss of visibility or control — in an ICS environment, Honeywell said in the report. Sixteen percent of the threats were specifically targeted at ICSes, and 15% contained known malware, including Stuxnet, Mirai, WannaCry and Triton. In addition to Trojans, other threats that were blocked included bots, hacking tools, and potentially unwanted applications.
Significantly, malware is not the only threat that USB devices pose.
"Malicious USB devices crafted specifically to attack computers via the USB interface have become readily available for purchase online," Honeywell noted in its report. "BadUSB — a technique that turns USB devices such as fans and charging cables into potential attack vectors — has increasingly been weaponized."