Introduction to Intentional Electromagnetic interference, IEMI (sv. EM-terrorism)
Electromagnetic terrorism, or Intentional Electromagnetic Interference, IEMI, is often defined as "the intentional malicious generation of electromagnetic energy introducing noise or signals into electrical and electronic systems, thus disrupting, confusing or damaging these systems for terrorist or criminal purposes". First, it should be mentioned that very severe incidents, with a large loss of life, money, property or public relations have already occurred due to unintentional electromagnetic interference. So it should from the start be clear that systems are vulnerable to electromagnetic energy, if these are not protected.
Due to the military heritage from the cold war and the research that grew out of the experience with electromagnetic effects on systems from nuclear explosions in the atmosphere (so called NEMP), much of the past research has focused on the effects of electromagnetic energy on military systems (such as aircraft, ships, communication systems or munitions). However as of the late 1980's, the focus has shifted. This shift in research is much in due to the huge increase in the amount of sensitive and sophisticated electronic systems (often commercial-off-the-shelf, COTS) being used in critical civil infrastructure components and everyday systems today. With the increased miniaturization these systems become inherently more vulnerable to disturbances. This means that supervisory and control systems in complicated distributed systems are today not especially hardened against electromagnetic interference, other than the regulated electromagnetic compatibility demands, which however experimental experience has shown is not adequate to handle intentional or uncommon disturbances.
It is important to mention that for IEMI there exist no (and this is not expected either) restraints on the type of disturbances considered as a threat. The main difference between IEMI and traditional EMC research is the human intent behind the disturbance. Thus, any type of spectrum for interference, ranging from low (few KHz or even Hz) to very high frequencies (GHz) could appear. Also, due to the previous military heritage, much research has focused on the threat from an antenna radiating fields of high magnitude (electric field in excess of 100 V/m) towards a system, however, this is barely half the side of the threat.
Due to the openness of civil society (accessibility) an eventual attacker could come very close to the intended target (e.g., a bank or control centre for some complex distributed system) in, e.g., a van carrying an electromagnetic weapon. But the same openness also creates another type of IEMI threat. An attacker could enter the before mentioned bank and locate an open port, that is a form of socket (power, lamp, computer, etc.) for a galvanic network, and inject a conducted transient into this network. Research has shown that such transients would spread far into, e.g., a power network of a facility, and interfere with all of the systems that are connected to this network (e.g., computers, servers, surveillance equipment etc.). The types of sources that could be utilized for this are sufficiently small to be placed in a small suitcase or briefcase, which would most probably go unnoticed, standing against a wall and connected to a power socket, in the lobby of a bank. Sources that are designed to, via an antenna, radiate a disturbance with some significant power, could be made equally small. These have already been demonstrated with "positive" results. Furthermore, the existing EMC regulation and testing has shown that the CE mark, supposedly showing a compliance with the EMC regulations, is not always valid. CE marked system could for some tested systems be interfered with at electric field levels far below the demands of the regulations. Thus, not only are non-hardened systems used for critical mission operation in infrastructures, the immunity of these are not as good as thought.
Thus, recapping a bit, the problem with IEMI, compared to traditional EMC is the human intent behind the interference ("is there a will there is a way"), the openness of the civil society (an attacker can come very close to the intended target) and that non-hardened systems and equipment (COTS) are being used for critical mission operations (of which much is known, e.g., working frequency, which can be used by an attacker). Also, today there are many possible electromagnetic weapons on the market (through commercial companies or through design schematics found on the internet) that requires no, or little, experience to be used.