As cybersecurity defenses continue to improve, cybercriminals have learned to become more creative with malware. We recently encountered threats being packaged inside old yet rarely used file types in spam campaignsSpam continues to be a cybercriminal favorite – this old-school infection vector makes up more than 48 percent of all email traffic worldwide.

https://blog.trendmicro.com/trendlabs-security-intelligence/same-old-yet-brand-new-new-file-types-emerge-in-malware-spam-attachments/