Malicious software

Malicious software (or malware), often generically called viruses, is computer software which deliberately does something harmful to your computer. Once downloaded, malware can be passed from one computer to another. Malware is usually downloaded to a computer by hiding inside rogue (and sometimes legitimate) software packages: the Trojan horse (or Trojan). While Mac malware is scarcer than Windows malware, Macs can pass on files that contain malware to Windows users, and one line of defense is to use a Mac antivirus that detects and stops Windows viruses as well as Mac malware.

Symptoms

If a Windows or Mac OS X operating system gets infected by malware, it could cause the loss of important files; business files, digital music and movies, and pictures could be wiped out by a single infection. The malware may slow down the computer or become annoying by sending email to all of the infected users contacts. Worse, it may delete or copy sensitive information on the infected computer or mobile device.

Infectious Mobile Devices

Android devices and some versions of the Apple iOS mobile operating system are vulnerable to malicious code contained in PDF files. Security researchers at Intego noted that while there is currently no known malware for iOS, files that flow through mobile devices and into home and office computers by email or remote storage can contain malware and worms that are harmful to the Mac and Windows operating systems. For example, once infected, an iPhone would act as an asympotomatic carrier, allowing cybercriminals to access confidential information, intercept phone conversations or take over other aspects of the infected device.

Macro Virus

One serious type of malware is macro viruses that affect Microsoft Word and Excel. These viruses spread among Word and Excel applications and documents, and, unlike other types of malware, affect Macs and Windows alike.