Security researcher says he has found a way of encoding viruses so they go undetected by most of the scanners he tested. The exploit involves MIME encoding, which was the subject of serious concern two years ago. Vulnerable scanners included BitDefender Mail Protection for SMB 2.0, ClamAV 0.88.7, F-Prot Anti-virus for Linux x86 Mail Servers 4.6.61 and Kaspersky Anti-Virus 5.5.10.”]
Source: https://www.csoonline.com/article/2120787/antivirus-scanners-confounded-by-mime-vulnerability.html