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Manipulating AIS

Spoofing the system is possible, but there are safeguards


By Glenn Hayes


AIS is an automatic tracking system used on ships and by Vessel Traffic Service (VTS) facilities for identifying and locating vessels by electronically exchanging data with other nearby ships, AIS base stations and satellites. It is an open-sourced system that relies on VHF broadcasts on open frequencies. As a result, it is vulnerable to malicious transmissions and runs the risk of being manipulated by individuals seeking to deceive the system. Just how serious and far ranging those vulnerabilities are depends on whom you ask.

AIS is vulnerable to data manipulation, spoofing and hacking, which can be broken into two main components. The most common and widely recognized issue of AIS manipulation has been with Internet-related usage of AIS data on publically available websites that display data compiled from multiple sources. It is the easiest source to manipulate and the validity of data used has been called into question. The other manipulation possibility is within the live AIS network of transmissions to and from vessels via VHF. 

Internet-based manipulation

Trend Micro, a software security company, brought internet manipulation of AIS data to light in 2013 with a report on its successful spoofing of vessels on one of the most popular Internet sites of its kind,, which reports vessel AIS information worldwide. As a crowd-sourced database the site receives and compiles AIS data from multiple sources and offers it for public access.

The company demonstrated by means of coding and computer equipment that it was able to spoof a vessel that was actually on the Missouri River by making it appear to be on a landlocked lake in Texas. However, it is important to remember the results were displayed on a website that is not used for navigation and as such did not present a threat to vessels navigating in either area. Another example of manipulation showed a vessel traveling a route that spelled out PWNED, a hacker term for a compromised system.

On the surface these hacks and spoofs seem to have little serious impact. Companies such as Windward have a different perspective. Michal Chafets, the head of communications for Windward, points to a report it published last year that detailed the issues and implications of altering AIS data fed to online AIS data suppliers.  According to the report, the system has “critical vulnerabilities when used to track ships, an ‘off label’ use of the [AIS] system; the data is increasingly manipulated by ships that seek to conceal their identity, location or destination for economic gain or to sail under the security radar.”

AIS data can be manipulated in various ways. Identity fraud can be accomplished by a vessel or hacker transmitting fake or stolen IMO (International Maritime Organization) information identifying the AIS transmissions as a vessel other then what it is. The report by Windward claims that this happens at an ever-increasing rate globally.

Another form of data manipulation is vessels obscuring their final destination in their AIS transmissions. Windward’s report claims that only 41% of vessels globally report their destinations and states this lack of data could skew views of commodity flows worldwide. This doesn’t seem to be a problem with Class B units, which don’t require manual data entry each time a vessel arrives or leaves port.

Going dark, or just turning off the AIS, is another way to alter AIS data reported online. Data collected by Windward claims a quarter of all vessels equipped with AIS have their AIS turned off at least 10% of the time, hiding their location.

 Yet another type of manipulation listed in Windward’s report involves GPS, where false GPS positions are input to a Class A unit to transmit a course or location other than where the vessel truly is. This could be done to hide activities such as fishing in restricted areas or a clandestine vessel rendezvous that needs to be obscured.

At least one AIS expert questions Windward’s motivation in publicizing the report, pointing out that the company is in the business of providing information to the maritime industry. Windward describes itself as a “specialized data and analytics company” that “provides its clients with the data, analysis and predictive capabilities they need to solve problems, make better decisions and monetize their interests at sea.”

While altering Internet-based AIS data can affect its validity, companies such as Windward and Trend Micro have software and analytics that can identify anomalies and flag instances where vessels drop out of the system or have extreme data variances. There are even some Internet sites that utilize specialized software to pick up some AIS anomalies created when AIS signals are manipulated. One is, a combined effort of SkyTruth, Oceana and Google’s Earth Outreach, which uses software that analyzes AIS data and determines the likelihood of fishing activity. It provides alerts when system anomalies occur that suggest illegal or unethical behavior. It is in the prototype stages but will be free to the public. The goal is to bring transparency and regulatory enforcement to illegal fishing activities worldwide.

Increased scrutiny and awareness of AIS vulnerabilities to Internet-based manipulation appears to be having a positive impact. Many companies now know about the limitations of AIS data sources and, like operating vessels, do not rely on just one source of information.

Next week in Part Two we'll look at the other type of manipulation: actually altering transmissions from ship to ship, ship to shore or from shore-based transceivers.


About the author

Glenn Hayes is a freelance photographer and writer based in west central Florida. His marine and boating industry experience extends back almost three decades. A second-generation professional photographer and journalist, he specializes in marine commercial, editorial and fine art photography and writes about all aspects of the marine and travel industries. He can be reached at



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