virus

A software program that replicates on computer systems by incorporating itself into shared programs. Viruses range from harmless pranks that merely display an annoying message to programs that can destroy files or disable a computer altogether. Whether they're considered malicious or malevolent, all viruses spread rapidly. For example, from one computer to millions of others around the world, infecting machines and causing them to crash. 

Viruses are most commonly transmitted through e-mail ("strains" have appeared that use personal e-mail address books to propagate themselves from machine to machine) but are also transmitted through backdoors. If you are connected to the Internet or any other network, it is important that you take precautions against viruses. Get a virus-scanning program and do not open any e-mail attachments from people you do not know.

Historical perspective: According to a security report released in 2012, a complex computer virus pilfered confidential information from computers in the Middle East. The Flame virus infected computers in Iran, Israel, Lebanon, Sudan, Syria, Saudi Arabia and Egypt and grabbed images of users' computer screens, recorded their instant messaging chats, remotely turned on their microphones to record their audio conversations and monitored their keystrokes and network traffic, according to a report by Kaspersky Labs, a Moscow-based security research firm.

Flame was the third major Internet weapon to have been discovered since 2010. The first, named Stuxnet, was intended to attack software in specialized industrial equipment, and was used to destroy centrifuges in an Iranian nuclear facility in 2010. The second, named Duqu, performed reconnaissance like Flame. Security researchers believe Duqu was created by the same group of programmers behind Stuxnet.The researchers said Flame appeared to have been developed by a different group of programmers. It contained 20 times more code than Stuxnet and was much more widespread than Duqu. Researchers believe Duqu hit fewer than 50 targets worldwide.

Kaspersky's researchers said they detected Flame on thousands of computers belonging to individuals, private companies and universities across the Middle East. The authors of Stuxnet and Duqu are also unknown but their targets and digital evidence suggest to some researchers that they may have been part of a joint American-Israeli project to sabotage Iran's nuclear program. Kaspersky's researchers said the majority of computers infected with Flame were located in Iran. Like Duqu and Stuxnet, Flame infects machines through a known security hole in the Windows operating software. Researchers discovered Flame while investigating reports that another computer virus, called Wiper, had been erasing computer programs in Iran. The International Telecommunications Union, a United Nations agency, had asked Kaspersky's researchers to look into Wiper when they discovered that thousands more computers had been infected with Flame.

Then in 2014, the Bash bug was exploited through a security flaw built into more than 70% of machines that connect to the Internet, including servers, computers, mobile phones, and even refrigerators and cameras. Unlike Heartbleed, the bug also discovered in 2014 that could be exploited to steal online passwords, the Bash bug according to Fast Company, allowed hackers to take over the entire machine they targeted, putting millions of machines around the world at risk.

Do Macs get viruses? Yes, but not nearly as much... read the NetLingo blog "One in Five Macs have Malware."