Viruses and Malware

Tens of thousands of virus/malware exist, with more being created each day. Computer viruses today can cause a great amount of damage by exploiting vulnerabilities in corporate networks, email systems and websites.

Trend Micro Security (for Mac) protects computers from the following virus/malware types:

Virus/Malware Types


Joke program

A joke program is a virus-like program that often manipulates the appearance of things on a computer monitor.

Trojan horse program

A Trojan horse is an executable program that does not replicate but instead resides on computers to perform malicious acts, such as opening ports for hackers to enter. This program often uses Trojan ports to gain access to computers. An application that claims to rid a computer of viruses when it actually introduces viruses to the computer is an example of a Trojan program.


A virus is a program that replicates. To do so, the virus needs to attach itself to other program files and execute whenever the host program executes.

  • Boot sector virus: A virus that infects the boot sector of a partition or a disk

  • Java malicious code: Operating system-independent virus code written or embedded in Java

  • Macro virus: A virus encoded as an application macro and often included in a document

  • VBScript, JavaScript, or HTML virus: A virus that resides on web pages and downloads through a browser

  • Worm: A self-contained program or set of programs able to spread functional copies of itself or its segments to other computers, often through email

Test virus

A test virus is an inert file that is detectable by virus scanning software. Use test viruses, such as the EICAR test script, to verify that the antivirus installation scans properly.


Packers are compressed and/or encrypted Windows or Linux™ executable programs, often a Trojan horse program. Compressing executables makes packers more difficult for antivirus products to detect.

Probable virus/malware

Suspicious files that have some of the characteristics of virus/malware are categorized under this virus/malware type. For details about probable virus/malware, see the following page on the Trend Micro online Virus Encyclopedia:


"Others" include viruses/malware not categorized under any of the virus/malware types.