Brokers have been urged to stay vigilant after scammers posing as TSB Intermediaries sent out malicious emails with fake mortgage offers on Monday.
In response TSB wrote to brokers warning them what was happening.
A TSB spokesman said: “Protecting our brokers is really important to us; that’s why we’ve already issued them with a few helpful tips about what to look out for in a genuine email from TSB Intermediaries.
“This includes to never open an attachment or link if you’re ever unsure about the sender.”
Mark Dyason, director of Edinburgh Mortgage Advice, was surprised malicious emails are being tailored to brokers, while he was struck by how realistic the fake offer looked.
In his case the phishing email was sorted into his spam, while the value of the property (£754,005) and suspicious sender (email@example.com) are giveaways.
But he said: “They nailed the appearance of the email.
“There is a sophistication coming in and we have to be more vigilant than ever because they will try and trick us.
“The amount of customer data we hold on our computers means we need to pay significant attention to this type of scam.
“Well done TSB for not sweeping it under the carpet by saying ‘someone’s having a go’.”
He added: “What’s most concerning is mortgage brokers are being targeted by mortgage-related emails.
“There’s a chance that some people will need more support and vigilance than others.
“The danger is for brokers and case managers who are under time pressure who see an email and click a link before they are sure.”