Malware targeting people's banking details is hitting 15,000 people's inboxes a day, security researchers warned this week.
The malicious macro virus masquerades as Microsoft Office and Excel email attachments coming from reputable retailers or banks, which contain a banking Trojan known as Dridex.
IT security firm Trustwave said in a blog post that once a user opens the document, the Dridex malware installs itself from a remote web server, and will secretly monitor keystrokes and grab screenshots of Internet Explorer, Firefox and Chrome browsers.
Dridex's XML configuration specifies which websites to capture submission forms from, meaning that victims entering credit card details on retail sites or personal details to their banking service are at risk.
Security research VP Ziv Maldor said: "You may think of document macro viruses as a thing of the past. But this year, some cybercriminal groups have revived this type of campaign in large numbers.
"The attackers lure victims to open the attachment by using brand names of reputable companies in the UK, across a variety of sectors.
"Some of the emails refer to an 'attached invoice' saying it is coming from a software company, online retailer or banking institution.
"Once the end user opens the attachment, the Dridex malware is installed giving the criminals access to their valuable information and enabling them to update the malware so that it avoids detection."
The resurgence of macro malware came with the release of Dridex in July 2014, but the scale of such attacks has increased dramatically recently.
Palo Alto Networks security researcher Ryan Olson wrote in October last year: "Its core functionality is to steal credentials of online banking websites and allow a criminal to use those credentials to initiate transfers and steal funds."
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