Picture courtesy of Matichon.

 

Cyber police have arrested a 35-year-old South Korean man who was allegedly driving around Bangkok with a false base station (FBS) device, sending out fraudulent SMS messages designed to trick people into handing over personal and banking details.

 

The suspect, identified as Mr. Dohyong Kim, was detained on Asok-Din Daeng Road after officers from the Cyber Crime Investigation Bureau (CCIB), working with engineers from AIS, traced abnormal frequency signals moving with his vehicle.

 

Inside the car, police found an operational FBS device, a mobile power supply, a signal distribution unit and three mobile phones. The equipment was being used to mimic legitimate network signals, allowing fake SMS messages with phishing links to be delivered directly to nearby phones.

 

Investigators discovered Telegram chats between Kim and a Chinese handler. He admitted he had been hired to drive through busy parts of Bangkok, broadcasting the fake messages and reporting his activity every 30 minutes. He said he had carried out the operation three times between 17–19 August, earning around 100,000 won per day, and had previously been paid USD 550 weekly for the work.

 

Police Major General Trirong Piwpan, Commissioner of the CCIB, said the crime formed part of a wider organised call-centre scam. He confirmed Kim faces charges including belonging to a criminal organisation, customs violations for possession of the illegal FBS device and potentially fraud and transnational crime if victims are identified.

 

Authorities also believe the gang may be linked to recent scams targeting Thai citizens. In the past three weeks alone, cyber police have arrested three suspects using the same method.

 

Officers warned the public to remain vigilant: “Banks and shopping centres will never send links requesting personal information. If you receive suspicious SMS messages, especially where your phone signal suddenly drops from 5G to 3G or below, do not click on any links and report immediately to the AOC hotline 1441 or emergency number 191.

 

The investigation is continuing to track down the Chinese mastermind who allegedly hired Kim.

 

 

  Adapted by Asean Now from Matichon 2025-08-21

 

 

 

Keep in mind this only works in a 3G network, 4G/LTE and 5G are much more secure and incredibly hard to do anything. 

But, this is how the attacker can get you to switch to a 3G network using the "Downgrade Vector" attack through a False Base Station (FBS) Operation.

 

The FBS device operates as a cell-site simulator and can sit on the back of any car or van.

The key mechanism here is protocol downgrade forcing. 

1. The FBS jams 4G/5G frequencies in immediate vicinity. (hardware is available for purchase online)
2. Phone searches for available networks since 4G/5G are unusable.
3. The new tower presents itself as strongest 2G/3G option, hardware also easily available online.
4. Phone now connects to 3G to maintain service.
5. SMS injection is now easy and possible through the compromised connection.

The warning about "signal drops from 5G to 3G" is the key sign here;  legitimate coverage changes are gradual, but FBS attacks cause sudden downgrades in areas that should have strong modern network coverage. That's how you know something is wrong 😉 

I've seen how it works, 17 years ago I was supporting a covert operation where we had to use this method to arrest a woman. a seriously dangerous woman.