There's a new ransomware that you should be aware of

Called 'AnteFrigus,' it is primarily distributed via 'malvertising' that redirects users to the RIG exploit kit.

One of the most unusual features of this strain is the fact that it specifically doesn't target the C: drive of the target computer.

Instead, it focuses exclusively on drives that are commonly associated with mapped network drives and removable hardware.

BleepingComputer was one of several organizations to discover the ransomware. They all contacted independent security researcher Vitali Kremez to reverse engineer the malware to get a peek under the hood at how it works.

Kremez discovered that this strain only targets the D:, E:, F:, G:, H:, and I: drives.  It does not even attempt to encrypt any files located on the C: drive, nor does it try to do anything whatsoever with unmapped network shares.

The AntiFrigus ransomware skips any file with the following extensions

  • Adv
  • Ani
  • Big
  • Bat
  • Bin
  • Cab
  • Cmd
  • Com
  • Cpl
  • Cur
  • Deskthemepack
  • Diagcap
  • Diagcfg
  • Diagpkg
  • Dll
  • Drv
  • Exe
  • Hlp
  • Icl
  • Icns
  • Ico
  • Ics
  • Idx
  • Ldf
  • Lnk
  • Mod
  • Mpa
  • Msc
  • Msp
  • Msstyles
  • Msu
  • Nls
  • Nomedia
  • Ocx
  • Prf
  • Rom
  • Rtp
  • Scr
  • Shs
  • Spl
  • Sys
  • Theme
  • Themepack
  • Wpx
  • Lock
  • Key
  • Hta
  • Msi
  • Pck

The fact that the ransomware studiously ignores the C: drive and the list of extensions the malware won't encrypt are curious. This all had many people scratching their heads trying to discern why the developers would build their code in this way.

Our perspective

Upon review, Kremez concluded that the developers are not terribly sophisticated and are, at this point, still in the experimental stages.  The code is still very much a work in progress.  Work in progress or not, it can be dangerous. Be sure your staff is aware of this latest threat.


~ As Hill Street Blues' Sgt. Esterhaus always advised: "Hey, let's be careful out there! " ~


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This free executive report may give you insights into how to build your business with safe IT environments: 10 Hidden IT Risks That Might Threaten Your Business and 1 Easy Way to Find Them

The author

Thanks for reading this short post. For more tips on thriving with small business technology, check out the other blog posts at DWPia Blogs. I am also available on LinkedIn, Facebook, and Twitter.

Cybersecurity Expert, Small Business Technology Consultant, Managed Services Provider, Managed IT SupportI am Denis Wilson, President and Principal Consultant for DWP Information Architects. I help professionals grow their business by building a foundation of rock-solid information solutions for smaller healthcare, insurance, financial, legal, and nonprofits firms in Ventura County and San Fernando Valley. And have created cost-effective IT solutions, for over 20 years, specializing in cybersecurity and regulatory compliance. I am also a published author and speaker, working extensively with a variety of organizations, as well as providing small business technology education programs through business and professional associations. This just in: I will be speaking regularly at California Lutheran University's Center for Nonprofit Leadership starting in September.

Contact me if you would like me to speak at your association.