Alexandre Barreto

Detecting malicious ADS-B broadcasts using wide area multilateration

Automatic Dependent Surveillance Broadcast (ADS-B) is an emerging radio technology capable of extending or replacing current RADAR-based surveillance for air traffic management. However, due to its reliance on unencrypted radio transmissions, ADS-B is exploitable using relatively inexpensive and open source tools. This paper demonstrates how multilateration technique can be applied to detect some types of malicious ADS-B transmissions, based on known GPS errors (used by ADS-B transmitters) and clock precision inaccuracies (used by multilateration systems). As it requires the measurement of radio signals time of arrival (TOA) at different sensors to calculate the transmitters location, the placement of those sensors play an important role to determine the accuracy of the estimates. In this direction, this paper also presents a method based on genetic algorithms in order to determine the position of sensors that gives improved coverage and reduced error.

Key distribution mechanism in secure ADS-B networks

Automatic Dependent Surveillance Broadcast (ADS-B) has been gaining attention as a replacement and strengthening of primary and secondary RADAR systems. Nevertheless, there have been several security concerns about this protocol because messages are sent in clear text, which makes it vulnerable to several attacks. In recent work, we addressed these concerns using a hash-based message authentication code (HMAC) that provides ADS-B with integrity and authentication capabilities. In this paper, we further develop this concept by proposing a key distribution mechanism that provides the proper infrastructure for the added safety and security features. The proposed mechanism addresses several common usage scenarios, including those that arise from air space being shared by manned and unmanned aerial vehicles.

An integrated mission and cyber simulation for Air Traffic Control

Worldwide statistics show that air traffic has been growing significantly in recent years. In order to maintain safety, new technologies and architectures are constantly being proposed and deployed. However, several of those technologies contain design flaws and security vulnerabilities which, if properly exploited, can affect the Air Traffic Control (ATC) system in such a way that its effects could range from simple flight delays (economic loss) to air disasters (loss of life). In order to better assess the new generation of air traffic services, this paper presents a simulation/emulation framework based on open source tools to able to evaluate the effects of cyber-attacks and network/communication failures on Air Traffic Control. It presents a case study on Automatic Dependent Surveillance - Broadcast (ADS-B) technology, with real implementations of cyber-attacks at the link layer. Furthermore, mitigation/defense mechanisms are also evaluated from a mission-assurance perspective.

Secure ADS-B design & evaluation

Automatic Dependent Surveillance Broadcast (ADSB) is a newer air traffic surveillance protocol that is expected to strengthen and replace current RADAR-based surveillance systems, which has brought worldwide attention. However, its nature of clear text broadcast introduces many vulnerabilities to the system. We proposed a solution that uses keyed-hash message authentication code (HMAC) to address the authenticity and integrity deficiencies of ADS-B protocol Previously. In this paper we extend it by improving the HMAC computation procedure at the transmitter and the HMAC verification procedure at the receiver. In addition, this new approach is also evaluated under some types of attacks, comparing its performance against unmodified ADS-B transmissions.

An ADS-B Intrusion Detection System

Advances in radio and RADAR research have considerably contributed to the emergence of novel air traffic control (ATC) protocols. In particular, Automatic Dependent Surveillance Broadcast (ADS-B) has proven to be a viable option that could complement and extend current technologies. Despite the benefits offered by ADS-B, such as more precise location, easier deployment, and lower costs, cyber-security issues have arisen due to the open, clear-text broadcasting of ADS-B messages making it vulnerable to many attacks. In this paper, we propose an intrusion detection system (IDS) specifically designed to detect malicious or questionable ADS-B messages. We leverage prior work on cyber-defense mechanisms against ADS-B attacks and physical aspects of aircraft motion to classify received ADS-B traffic as potential attacks and retain digital artifacts that might support post-attack forensic investigations.

Secure ADS-B framework “ADS-Bsec”

In this paper, we leverage previous work on securing Automatic Dependent Surveillance Broadcast (ADS-B) to propose a secure ADS-B framework that substantially enhances the original safety and security solutions. The enhancements are obtained by feeding real flight data along with malicious data at the secure ADS-B sender and observing the outcome at the secure ADS-B receiver that we developed as part of our research on ADS-Bsec. To evaluate our ideas, we built a trajectory predictor module based on Base of Aircraft Data (BADA) and, together with well-defined departure and arrival airports, generated a synthetic, yet realistic aircraft data set. The experiments focus on describing how our system reacts to known ADS-B attacks, and the results obtained so far and presented in this paper are consistent with our expectations of enhancements in both safety and security of ADS-B operations.

Using a P2P architecture for voice and radar transportation in critical command and control systems

The Brazilian air traffic service is constituted by a civil and a military organization, which provide tracking (radar), voice and data communication (VHF, UHF and HF) services, through an integrated network. To optimize the management of its air traffic system, Brazil divides the airspace into four independent Regional Centers. In each of these regions, the existing sensors (radars and radios) send information and products to only one of the Regional Centers, forming a star topology. In case of impediment in one Regional Center (eg, electrical failure or terrorist attack), even if the service node is able to send its information, the Regional Center will collapse, since there is no means to process the information generated locally. The solution presented in this article, develops the redundancy of the system through the digitization of audio and radar signals and its subsequent transport using an peer-to-peer network. To validate this proposal, experimental flights were developed. In these flights, aircraft flying over the city of Manaus (in the center of Amazonia) were coordinated by a center installed in Brasilia, which is located about 1000 km away. After these experiments, it was concluded that using this new architecture, we can provide a performance similar to those currently in operation, enabling air traffic systems, as well as those of similar function (eg coordination of civil defense and police ) to be operated with a high degree of reliability, even when they meet a hostile environment.