China spammers’ latest weapon: fake base stations

When your blogger lived in Beijing I used to turn my phone off at night so as not to be disturbed by spam texts for massage services and fake receipts.

That was six years ago. Not much has changed.

One recent study concluded that 200 billion spam SMS were sent to Chinese mobile phones in the first half of the year – that’s more than 180 for each user, or one a day. In big cities like Beijing and Guangzhou, that rises to around 2.5 per day.

The economics of this might seem puzzling, given the cost of sending SMS. But not if you have your own base station. 

The Beijing News recently related the tale of a professional spammer who roams the Chinese capital with a small cell transceiver in his van, charging 1,000 yuan ($164) to reach thousands of users within several hundred metres.

The spammer, Guo Peng, said he had five GSM small cells, each costing around 50,000 yuan ($8,220), with which he earns up to 5,000 yuan a day. He can send out 6,000 messages in half an hour via the China Mobile or China Unicom networks. Guo said he knew at least 20 others in the business in Beijing, each with multiple base stations.

Reportedly, Guo’s spoof base station shields the operator's signal for up to 20 seconds at a time, during which it transmits to handsets in the area. Anyone who is on the phone at the time will lose their call – in some cases they may even have to reboot the phone to get their signal back. 

Guo said he used the China Mobile recharge number as his transmit number – “it’s a lot more credible.” 

The story emerged from a Beijing News journalist who teamed along with a businessman friend who had hired Guo to promote his local supermarket.

Guo picked them up in his van on a street in southern Beijing and drove to a seafood market near the supermarket. Guo’s colleague in the backseat fired up the small cell through a laptop and within 20 minutes had sent 2,593 texts.

In the half hour while he was sending spams, he took ten phone calls, all apparently from prospective customers. Clients included travel firms, real estate developers, even gun dealers and spammers themselves – they like to eat their own dog food, which surely makes them not hard to find. 

An official at the Beijing Communications Bureau said base station spoofing was on the rise but “very hard” to investigate.

Guo says he once had a call from a police officer about a text he’d sent, but he explained it away as “a joke”.

Guo and other spammers are helped by bureaucratic boundaries. The police are not interested unless it involves illegal activity, so the relevant authority is the State Administration of Industry & Commerce, which regulates commercial activity.

The scale of the problem also underlines the indifference of operators to their customers, not to mention  the limited competition between them.

The journalist even tracked down a store that specialised in selling unauthorised small cells. A staff member, Ms Li, said the biggest buyers were large shopping malls – yet somehow this store and its customers are too elusive for China’s well-resourced bureaucrats.