In a terrestrial environment, threat actors use traffic analysis attacks to analyze traffic flow to gather topological information. This traffic flow can divulge information about critical nodes, such as the aggregator node in a sensor network. In the space environment, specifically with relays and constellations, traffic analysis can be used to understand the energy capacity of spacecraft node and the fact that the transceiver component of a spacecraft node consumes the most power. The spacecraft nodes in a constellation network limit the use of the transceiver to transmit or receive information either at a regulated time interval or only when an event has been detected. This generally results in an architecture comprising some aggregator spacecraft nodes within a constellation network. These spacecraft aggregator nodes are the sensor nodes whose primary purpose is to relay transmissions from nodes toward the ground station in an efficient manner, instead of monitoring events like a normal node. The added functionality of acting as a hub for information gathering and preprocessing before relaying makes aggregator nodes an attractive target to side channel attacks. A possible side channel attack could be as simple as monitoring the occurrences and duration of computing activities at an aggregator node. If a node is frequently in active states (instead of idle states), there is high probability that the node is an aggregator node and also there is a high probability that the communication with the node is valid. Such leakage of information is highly undesirable because the leaked information could be strategically used by threat actors in the accumulation phase of an attack.
| ID | Name | Description | NIST Rev5 | D3FEND | ISO 27001 | |
| CM0062 | Dummy Process - Aggregator Node | According to Securing Sensor Nodes Against Side Channel Attacks, it is practically inefficient to prevent adversaries from identifying aggregator nodes in a network (i.e., constellation) because camouflaging traffic in sensor networks is power intensive. Consequently, focus on preventing adversaries from identifying valid aggregation cycles of aggregator nodes. One solution to counter such attacks is to have each aggregator node execute dummy operations that resemble the average power consumption curve observed during the normal operation of the aggregator node. Apart from simulating the power consumption of a genuine process execution, the two necessities that the execution of the dummy process must incorporate to be successful in thwarting the accumulation phase are to use a different dummy execution process each time or have a low repetition rate. This should help prevent the attacker from finding a pattern that would differentiate the execution of a dummy process from the normal execution of an aggregator node. The second requirement relates to the timing of the execution of the dummy process. Depending on whether there is a pattern to the timing of the execution of a dummy process, a threat actor may be able to identify and disregard the dummy process. For example, if a threat actor is capable of identifying the presence or absence of a radio frequency transmission, the attacker can disregard any power consumption curve computed during the absence of transmission signal. Similarly, if the dummy process is not executed every time the aggregator node receives a transmission, the attacker will be able to identify invalid transmission. Hence, to ensure the effectiveness of this scheme, the dummy process must be executed each time the aggregator receives a transmission as well as randomly during idle periods. The advantage of incorporating dummy processes in an aggregator is to minimize the ease of identifying transmission flow in a sensor network that can be used to identify the base station of the sensor network, which could be highly confidential in critical applications. | PE-19 PE-19(1) | A.7.5 A.7.8 A.8.12 | ||