If you learn that you’re among the estimated 100,000 Canadians whose personal information – including addresses, social insurance numbers and credit card details – may have been compromised in the massive Equifax hack, cybersecurity expert Brian O’Higgins has some advice.

Step one, breathe. Step two, roll up your sleeves and begin a personal data crackdown.

“If this gets in the wrong hands, it could be used by people to take out a mortgage or a line of credit in your name, and you could be in a world of hurt as a result of that,” O’Higgins told CTV News Channel on Tuesday. “You need to be vigilant and check your credit situation.”

Equifax Canada said it has already reached out to MasterCard and Visa about those customers who were swept up in the security breach, which may affect 143 million Americans and an undisclosed number of customers in the U.K.

The credit card companies are expected to reach out to those Canadians impacted.

If you get the call, O’Higgins recommends taking a proactive approach to guard against identity theft.

“Definitely get a credit-monitoring service. Equifax is now, I believe, required to provide this free for a year. Consider extending that almost forever,” he said.

Most major Canadian banks offer credit monitoring, which helps keep track of any suspicious activity that could potentially be linked to identity theft.

“That will give you reports if anyone is poking around any transactions that might be potentially fraudulent, and then you could jump on it right away,” he said.

O’Higgins warned that con artists will likely be “on the march” after the security breach looking for ways to scam consumers.

“You might get a random phone call or pop up saying, ‘I’m from Equifax, I here to help, let me verify some information,’” he said. “Be cautious and be vigilant.”

Equifax collects data about users’ credit pasts and offers credit checks to companies.

An investigation into the data breach was launched last week by Canada’s privacy watchdog.

With files from The Associated Press