Email is part of daily life and provides a quick way to send and receive important documents and pictures that can be saved on your local computer. This makes digital attachment files vulnerable to use as vehicles for malicious software. Spyware and malware such as Trojan horses, worms and viruses can be embedded in just about any email attachment, including cute pictures of puppies and cats and even PDF files. This malware can corrupt your hard drive, steal your data and expose you to all sorts of online and offline fraud.
Malware is a generic term used to refer to malicious software. This could take the form of computer viruses, Trojan horses, worms and spyware. The malicious software is usually a program that can either be sent as an executable email attachment (a file with an EXE attachment) or made to look like a harmless file, such as a text file or TXT, but these often have hidden extensions. More sophisticated malware comes embedded within images such as JPEG files and PDF files and are activated when you open the image or view the PDF. These will look the same as any other harmless image or PDF document to the average viewer.
Malware can delete files from your hard drive, corrupt data or even completely disable your computer or mobile device. Some malware have specific functions such as writing code on your hard drive that turns your machine into a zombie for nefarious purposes or spying on your activities and sending data to an external location. The latter can leave you vulnerable to fraud such as having your banking information stolen and your cash removed, or to identity theft and credit card fraud.
Your first line of defense is to ensure that you have updated anti-malware software installed on your computer or device that scans every email attachment before opening it or downloading it to your local drive. Open only email attachments that you were expecting to receive and ideally only after you’ve confirmed the legitimacy with the sender using a different means of communication than email. Don't open attachments in junk mail, and don't open any unexpected attachments or attachments from people you don’t know.
If you’ve accidentally clicked on an infected email attachment, your first action should be to cold-power-down your device. Don't attempt to save anything and don't use the “Shut Down” option on your computer. Malware is software and its installation process is much the same as that of harmless software. If you stop it early, you can curtail some of the damage. Next, reboot your computer and press "F8" repeatedly, and then enter Safe Mode from the boot menu. Run a system scan with your updated anti-malware application and remove any detected risks before resuming normal use of the machine. Schedule regular full system scans to detect any risks that you may have missed on the initial scan.
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