Malware is a portmanteau, a term combining "malicious" and "software" to describe a type of program designed to steal information from or cause damage to a computer. It includes things like spyware and adware programs, including pop-ups and even tracking cookies, which are used to monitor users' surfing habits without permission. It also includes more sinister hazards, such as keyloggers, Trojan horses, worms, and viruses. In simpler terms, it is any software that is intended by the developer to cause harm or exploit people's computers or private records without consent.
The Threat Posed by Malware
The threat posed by malicious software has expanded roughly in parallel with the number of people using the Internet around the world. The earliest well-known examples of malware, which appeared during the early to mid-1990s, were largely the result of experimentation and pranks by curious developers trying to expand their skills. Many of these caused little if any actual harm, and simply resulted in uncommanded actions such as displaying a humorous image on the victim's computer screen. This gradually gave way to efforts to exploit infected computers for annoying but relatively mundane purposes, such as distributing spam email and other forms of advertising.
As Internet usage became more widespread, however, a new term was coined: cyber crime. People with bad intentions quickly realized the potential for using these same tools for stealing, extortion, and carrying out various political agendas. Other perpetrators have used dedicated software to target specific victims; this would include so-called "denial of service attacks" against large companies or government agencies, as well as programs designed for identity theft. To make matters more confusing, it is widely believed that the governments of many countries have either experimented with or have directly employed malware to carry out attacks against enemy groups or nations, as well as for intelligence gathering; experts commonly refer to this as electronic warfare.
Types of Malware
Though new types of malicious software are constantly under development, these programs generally fall into a few broad categories. Viruses are perhaps the best-known category, and consist of harmful programs designed to "infect" legitimate software programs. Once a person installs and runs the infected program, the virus activates and spreads itself to other programs installed on the computer before taking further action such as deleting critical files within the operating system. Similarly, "worms" are stand-alone programs that are able to transmit themselves across a network directly. Both types of malware can cause severe damage by eating up essential system resources, which may cause the victimized computer to freeze or crash. Viruses and worms commonly exploit shared files and databases like email address books to spread to other computers.
Less obvious but equally insidious threats include keyloggers, programs that record every keystroke the user makes and then forward that information to whomever installed the program to begin with. This makes it possible to steal information such as passwords, bank account numbers, and credit card numbers. A Trojan horse is a malicious program disguised within another piece of software that appears to be legitimate. Once installed, however, the Trojan may install a "backdoor" through which to retrieve personal information and transfer it to another computer. Hackers commonly employ these forms of malware for perpetrating identity theft.
PCs vs Macs
It is generally true that PCs are more likely to fall victim to malware than Apple Macintosh® machines. There are many theories behind why this is so. Some suggest that the sheer number of Windows® PCs in existence makes them a more profitable target. Other experts have suggested that the architecture of the operating system used in Macs is designed in a way that makes it harder to hack. Despite these advantages, Mac-oriented viruses and related hazards are out there, and reasonable precautions are just as important as they are for PCs.
Countering the Threat
Anti-virus programs are good protection when kept up to date. Some of these products can even scan email for any type of malicious or suspicious code, and alert the user to its presence, even if it is not currently recognized. Frequently, however, they miss certain types of threats, such as Trojans and spyware, so it is a good idea to run at least one anti-adware program in conjunction with anti-virus. Using a firewall is also helpful because, while it won't keep malware out, it can keep such programs from accessing the Internet and delivering personal information to the intended target.
No single product can guarantee to protect a computer from all of these malicious programs. Developers on both sides are locked in a constant battle to get ahead of the other. Ultimately, the user is the last line of defense by being cautious about opening emails from unknown sources, and steering away from disreputable websites.
Hunting Down the Culprits
While developing software to detect, remove, and undo the damage has become a profitable industry, there is also a concerted effort underway to bring those responsible to justice. This is a huge challenge because even though cyber criminals often form large underground organizations, the individual participants are typically scattered around the world, and can communicate or do their work from any location that has a computer and Internet access. Only through international cooperation can law enforcement agencies be effective; indeed such joint operations have led to some dramatic successes. Not all governments are equally cooperative, however, and some seem to turn a blind eye altogether, greatly impeding attempts to attack the problem at its source.