What is a virus? A computer virus is a program – a piece of executable code – that has the unique ability to replicate. Like biological viruses, computer viruses can spread quickly and are often difficult to eradicate.
They can attach themselves to just about any type of file and are spread as files that are copied and sent from individual to individual. In addition to replication, some computer viruses share another commonality: a damage routine that delivers the virus payload. While payloads may only display messages or images, they can also destroy files, reformat your hard drive or cause other damage. If the virus does not contain a damage routine, it can cause trouble by consuming storage space and memory, and degrading the overall performance of your computer.
Several years ago most viruses spread primarily via floppy disk, but the internet has introduced new virus distribution mechanisms. With email now used as an essential business communication tool, viruses are spreading faster than ever. Viruses attached to email messages can infect an entire enterprise in a matter of minutes, costing companies millions of euros annually in lost productivity and clean-up expenses.
What is malware?
Malware – short for malicious software – refers to any malicious or unexpected program or code such as viruses, Trojans and droppers. Not all malicious programs or codes are viruses. Viruses, however, occupy a majority of all-known malware to date including worms. The other major types of malware are Trojans, droppers and kits. Due to the many facets of malicious code or a malicious program, referring to it as malware helps to avoid confusion.
What is a trojan?
A Trojan is malware that performs unexpected or unauthorised, often malicious, actions. The main difference between a Trojan and a virus is the inability to replicate. Trojans cause damage and compromise the security of systems, but do not replicate. If it replicates, then it should be classified as a virus. A Trojan, coined from Greek mythology’s Trojan horse, typically comes in good packaging but has some hidden malicious intent within its code.