‘SILENT assassins’ are targeting online banking usernames and passwords in the city, police have warned.
Banking Trojan attacks have spiked over the last few months with 1,800 suspected such hacks in Hampshire.
Firms and individuals have been warned to take steps to protect themselves or face having their cash stolen.
Between October 2016 and March there were 179 incidents in Charles Dickens and Nelson wards in Portsmouth.
This was the second worst hotspot in the county. Action Fraud reports the data to Hampshire police.
The Gosport East area and Fareham suffered between 49 and 69 infected IP addresses.
Nigel Taylor from Taylor Made Computer Solutions, in Fareham, said: ‘These Trojan attacks are like the silent assassins of the hacking world.
‘They’re particularly dangerous because they lay dormant in the background, with users often completely oblivious to their existence. It’s only when they log into their banking portal or PayPal account that the drama unfolds.’
He warned people to hover over links before deciding whether to click on them.
It comes just weeks after a five-day investigation published by The News found Hampshire police is setting up a new dedicated unit and that nationally few cyber crimes had been cracked.
The trojan hack infects a web browser via a link or attachment, then stays dormant waiting for a person to visit an online banking website.
It steals the username and password, sending this to a cyber criminal somewhere across the globe.
Money mules then courier the cash. In some cases a log-in screen is changed, with a victim using a fake website.
Lucy Dibdin, cyber security and protection officer at Hampshire police, said: ‘Whilst it is not possible for us to identify each of the users of the IP addresses affected, we urge anyone who does their banking online to take some simple steps to help safeguard their security.
‘Banking Trojans are malicious software (malware) specifically designed to break into an online bank account and transfer money to other accounts controlled by criminals.’
Police are warning people to protect personal details, not to disclose them to anyone or to websites.
A spokesman for UK Finance, which represents firms in the industry, said: ‘Banks treat fraud extremely seriously and use a range of sophisticated security features to identify suspicious activity. But as banks invest in these measures, criminals are increasingly turning to impersonation scams to trick people out of their personal details and money.’