WARSAW: Unidentified assailants have used radio signals to halt 25 passenger trains in Poland, according to state rail operator PKP, reported German news agency dpa.
A railway spokesman told the PAP news agency that the trains were stopped in four regions around 1 pm on Tuesday. There was no danger to passengers. All trains were able to resume their journeys with a slight delay.
There have been several such attacks on the Polish railway network in the past few days.
The railways serve as the main transport route for Western military aid to Ukraine. It is not clear whether the attacks have a political dimension.
Police in Bialystok in the east of the country already arrested two men on Sunday. Investigators found radio equipment on them.
The suspects, one of whom is a police officer, allegedly brought five passenger trains and one freight train to a standstill on Sunday morning.
Trains have also been stopped in western Poland. The Russian anthem is said to have been heard during the stops, as well as a speech by Russian President Vladimir Putin.
Technically, the attack is relatively simple, cyber security expert Lukasz Olejnik explained in the daily newspaper Dziennik Gazeta Prawna.
Radio technology without encryption is still used in many Polish trains. To stop trains, all you need is a tone generator and a radio that emits a sequence of three tones twice in succession on a specific frequency, the expert added.
“Such a signal triggers a sudden stop via a valve in the air brake system.” This security gap in the Polish railway system has been known for a long time, according to Olejnik. As a result, there have occasionally been similar attacks in recent years. – BERNAMA-dpa
