Online users who have received unexpected email messages with attached files with names ending with ".z" are asked not to open them. This is because the attachments are compressed files that may contain malware, malicious programs or viruses. And, any attempt to open the malicious attachments will result in the recipients getting their computers infected with a virus, Trojan horse, spyware, ransomware or other malware.
A Sample of a Malicious ".Z" Email Message
Re: Purchase Order
Tue 4/23/2019 2:52 PM
From: Sales and Market Manager
Attachment: Order No.955774.pdf.z (736 KB), Scan_955774.rar (736 KB)
We are sending Purchase Order has been attached.
Please find the attachment.
With Thanks & Regards,
Sales and Market Manager
Energy Build Your Home
FUAN EAGLES ELECTRICAL MACHINERY CO.,LTD
Whatsapp / Mobile: +86 13850389799
Alternative Email: email@example.com
Wechat/QQ: 48767515 Skype: yilong-john
"We appreciate you considering us as your Supplier!"
.Z is a file extension for a compressed archive file used with Unix-based systems. Z file archives were commonly used when creating a compressed archive to magnetic tape for backup purposes. Z files can be opened by most current compression software, including Winzip (Windows) and Tar (Unix/Linux).
Cybercriminals usually store their malware in compressed files to help prevent antivirus software from detecting them. In other words, they do it because the compressed malicious email attachments may bypass the recipients' antivirus software.
What is a .Z file?
GZ files are compressed files created using the gzip compression utility, which was initially created by two software developers to replace and improve on Compress in UNIX. This utility is most commonly used on UNIX and Linux systems.