Clickbait: Telstra switches on filter to stop dodgy SMS texts

Telstra has switched on a new scam filter designed to keep users from being bombarded with dodgy SMS messages. But don’t expect it to eliminate unwanted political texts during the election, including from Clive Palmer.

The telco said it had activated the new technology — which works at a network level to stop suspicious messages before they reach their destination — for all customers of Telstra mobile and virtual operators that use Telstra’s network.

Complaints about scammy text messages more than doubled in 2021.

The system is designed to sniff out malicious URLs and spot patterns of criminal automated scam campaigns, while still letting through human-made texts and legitimate automated messages from businesses and government. A Telstra spokesperson confirmed the telco did not have the authority to block political messages, which have an exemption under law meaning they can be sent without the receiver’s consent.

The bulk and sophistication of criminal scams in general is on the rise, with the Australian Competition and Consumer Watchdog reporting Australians lost $38 million to scams in February alone, up from $14.5 million for the same month in 2020.

For text messages specifically, the ACCC received 67,000 reports of scams in 2021, more than double the 32,000 in 2020.

Telstra chief Andy Penn said regulatory changes had enabled far superior SMS blocking.Credit: Eamon Gallagher

“We saw a very significant increase in digital adoption during COVID. Many people moved to working or studying from home, doing shopping and medical things online,” said outgoing Telstra chief executive Andy Penn.

“And that created an environment in which malicious actors could use that extra activity to trick people into clicking on scam texts.”

Telstra processes about 50 million text messages a day, and Mr Penn said it expected to block up to 2 million. This is an automated process that spots scams using machine learning, trained during a months-long trial with two and a half thousand Telstra employees.

The technology was enabled by regulatory changes made late last year, which modified how telcos could legally scan the contents of private text messages. “We were always able to monitor metadata, but [by working with government] we were able to get some clarification on what constituted content and what didn’t,” Mr Penn said.

“Which enabled us to improve the sophistication of our surveillance on SMSs across the network, which means that we can therefore increase our level of blocking.”

Telstra said human specialists would look at blocked texts only very rarely, when the system wasn’t sure if a message was a scam or legitimate, and in those cases the contents would be anonymised.

Adrian Covich, senior director at cybersecurity firm Proofpoint, said automated systems had a role to play in reducing the impact of SMS scams. But more important was tackling the human behaviour that allowed them to spread.

“There’s been a lot of innovation around mobile malware. This isn’t just a guy sitting down, typing each one of these and sending it out,” he said.

“Particularly we’ve seen a malware variant called FluBot, which has been infecting Android phones, and basically it’s both propagated and funded by these messages.”

FluBot and similar malicious software gets into phones by tricking people into clicking on links, for example by embedding them in messages claiming to be from a bank or courier. Once installed they steal valuable data, but they also use the victim’s phone number to send more messages to others.

Mr Penn said Telstra customers would be able to report suspect messages that made it through, and also had the option to turn off filtering entirely.

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