In a blog post, Proofpoint said TA505, a prolific actor that has been responsible for numerous campaigns spreading the Dridex malware and also the Locky ransomware, this time appeared to be targeting banks, retail businesses and restaurants.
The TA505 group started distributing ServHelper in early November 2018, Proofpoint said, starting with a small email campaign that contained Microsoft Word or Publisher attachments containing macros which, when enabled, downloaded and ran the associated malware.
In mid-November, a larger campaign was observed from TA505, using .doc. .pub or .wiz attachments that contained macros. These macros led to the installation of the downloader variant of ServHelper.
Proofpoint claimed these new threats were part of a trend visible in 2018, in which the focus was on downloaders, information stealers and remote access trojans that could stay on a victim's system for a long time. This was in contrast to ransomware which made its presence known soon.
"We will continue to observe the distribution of these three malware variants but, at this time, they do not appear to be one-offs, but rather long-term investments by TA505," the company said.
A detailed technical analysis of ServHelper and FlawedGrace is here.