Police have arrested six people and seized dozens of illegal SIM boxes used to send millions of scam text messages to trick people into downloading malware or sharing personal information.

Federal and state police forces launched a national day of action in a bid to protect Australians from scams that rake in tens of millions of dollars.

SIM boxes are used by cyber criminals to commit large-scale SMS phishing attacks known as “smishing” – the use of deceptive text messages to spread malware or harvest personal information.

The scams target Australians through their banking or government-affiliated online accounts.

The AFP and state police forces worked together to execute six search warrants, leading to four arrests in NSW and two in Victoria on Thursday.

Police seized 29 SIM boxes, thousands of mobile SIM cards, laptops, hundreds of mobile phones, stolen identity documents, $166,000 cash and two luxury vehicles worth $330,000.

The SIM boxes have multiple slots for SIM cards and are connected to computers which program them to send scam texts constantly. 

The charges against those arrested include using equipment connected to a network to commit a serious offence, dishonestly obtaining/dealing in personal financial information and dealing with identity information to commit an indictable offence.

AFP Detective Superintendent Tim Stainton said SIM boxes were “cheap and malicious machines” used by criminals to defraud hundreds of victims at a time. 

“Criminals will send millions of deceptive text messages to Australian mobile users, casting a wide net over the entire community in an attempt to trap and defraud as many victims as possible,” he said.

“If not disrupted through police action, the SIM boxes had a combined potential to continue to distribute between four and six million fraudulent messages every day.”

Supt Stainton said the AFP was working tirelessly with its law enforcement partners to eradicate the criminal exploitation of SIM boxes nationwide.

“We encourage people to protect themselves against phishing scams by carefully reviewing emails or text messages before clicking on any links.”

In NSW, police seized 26 SIM boxes which had sent more than 318 million messages over past months, scamming victims out of millions of dollars.

NSW cybercrime squad commander Matt Craft told reporters on Friday the operation was a significant blow to organised crime in Australia and he warned police action against cyber criminals was ongoing and they would be caught.  

“We are technically proficient and you can be identified and you will be identified,” he said.

Victoria Police Detective Superintendent Tim McKinney said a single SIM box could hold more than 100 SIM cards and was capable of sending hundreds of thousands of malicious text messages a day.

“It involves criminals essentially casting their net out far and wide and taking advantage of the trust the community has in legitimate business names,” he said.

“They rely on a handful of unsuspecting recipients clicking the link and inputting their details, and the consequences for those people can be devastating and life changing.”