The UK's banks are constantly under threat from sophisticated cyber threats that could cause a great deal of damage to their operating model, according to a new report from BBC News.
Data from three sources indicates that spam, viruses and other malicious messages regularly emerge from machines sitting on banks' corporate networks, the organisation found.
All banks have extremely strong processes in place to avoid losing any sensitive information, but as criminals become more technologically savvy and capable of hacking more complex systems the risk is likely to increase.
One of the biggest problems is when bank staff and contractors visit sites that then infect their computer with booby-traps, BBC News claimed.
James Lyne, global head of security research at security firm Sophos, said a 'botnet' getting access to banking networks would be extremely concerning.
This is a collection of programmes connected to the internet that can report back to another device, potentially allowing a criminal to access financial services information from a remote location.
"It would give attackers a foothold that they can exploit," explained Mr Lyne.
Sources inside UK banks told the BBC that they deal with up to a dozen incidents a month of employees' machines getting infected with malware, while phishing emails are also a concern.
There have been more than 20 issues involving malicious network activity over the course of 2013 so far, according to BBC News.
While banks spend a great deal on IT security, experts are concerned that more needs to be done to prevent staff from accessing external - and potentially harmful - websites.
Professor Michel van Eeten from Delft who leads the team gathering data on botnets warned that there is a "consistent" problem with botnets across the banking sector in the UK.
"If they are vulnerable to that you have to wonder what else they are vulnerable to. This might show they can fall victim to a targeted attack more easily because those are much harder to avoid falling into," he declared.