The Control Systems Security Program and other programs within the Idaho National Laboratory have discovered a vulnerability common to control systems in all sectors that allows an attacker to penetrate most control systems, spoof the operator, and gain full control of targeted system elements. This vulnerability has been identified on several systems that have been evaluated at INL, and in each case a 100% success rate of completing the attack paths that lead to full system compromise was observed. Since these systems are employed in multiple critical infrastructure sectors, this vulnerability is deemed common to control systems in all sectors.
Modern control systems architectures can be considered analogous to today’s information networks, and as such are usually approached by attackers using a common attack methodology to penetrate deeper and deeper into the network. This approach often is composed of several phases, including gaining access to the control network, reconnaissance, profiling of vulnerabilities, launching attacks, escalating privilege, maintaining access, and obscuring or removing information that indicates that an intruder was on the system. With irrefutable proof that an external attack can lead to a compromise of a computing resource on the organization’s business local area network (LAN), access to the control network is usually considered the first phase in the attack plan. Once the attacker gains access to the control network through direct connections and/or the business LAN, the second phase of reconnaissance begins with traffic analysis within the control domain. Thus, the communications between the workstations and the field device controllers can be monitored and evaluated, allowing an attacker to capture, analyze, and evaluate the commands sent among the control equipment. Through manipulation of the communication protocols of control systems (a process generally referred to as “reverse engineering”), an attacker can then map out the control system processes and functions. With the detailed knowledge of how the control data functions, as well as what computers and devices communicate using this data, the attacker can use a well known Man-in-the-Middle attack to perform malicious operations virtually undetected.
The control systems assessment teams have used this method to gather enough information about the system to craft an attack that intercepts and changes the information flow between the end devices (controllers) and the human machine interface (HMI and/or workstation). Using this attack, the cyber assessment team has been able to demonstrate complete manipulation of devices in control systems while simultaneously modifying the data flowing back to the operator’s console to give false information of the state of the system (known as “spoofing”). This is a very effective technique for a control system attack because it allows the attacker to manipulate the system and the operator’s situational awareness of the perceived system status. The three main elements of this attack technique are: 1) network reconnaissance and data gathering, 2) reverse engineering, and 3) the Man-in-the-Middle attack.