Instant messaging has been around longer than the internet. However, it didn't become a world famous phenomenon until the internet revolution. Almost immediately after instant messaging (or IM-ing) became popular, people started looking for ways to exploit it. While instant messaging can be a fun and convenient way to communicate, it can also be dangerous without the proper precautions.
Many of the same rules that apply to email security also apply to IM security. Never accept any sort of file from someone that you do not know. The authors of viruses and other malicious programs have automated systems that routinely send millions of messages to unsuspecting (and some suspecting) IM users, attempting to trick them into downloading harmful or invasive software. In contrast to email, which has since has had laws made to protect email users from spam, there are no specific laws pertaining to IM usage, and thus it is considered by some to be more volatile than email.
In order to protect yourself, first and foremost, make sure that the instant messaging application that you download is a known and trusted one, and that you download it from their official site. Among some of the most popular instant messaging applications are:
AIM
Jabber
Yahoo! Messenger
Windows Live Messenger
ICQ
Another way that malicious wares are delivered to users is by tricking IM users to click on URLs that direct them to a site that automatically downloads the harmful program. Several different techniques are used to illicit a click through from the IM user, most commonly by trying to convince the user that they are being invite to an adult website (many times by claiming that they are in fact one of the models on the site). After the computer is infected, in many cases the virus will cause it to immediately resend itself to everyone on the user's buddy list. Because many of the users on his or her list are likely to trust the message, they are likely to click the link or download the file, causing the virus to propagate incredibly quickly. Although some IM-derived infections are classified as nearly a nuisance, others are considered criminal activity. Methods of using IM to distribute viruses are becoming more sophisticated each and every year.
Attempts to deliver harmful files via instant messaging are not the only threats you may encounter. Practitioners of "phishing", a process by which users are tricked into submitting personal information, is another common problem associated with IM. Criminals will send mass amounts of instant messages, often times with screen names implying they are associated with a reputable company (Ebay, PayPal and online banks are common targets). They will then attempt to get you to click on their link to a site that usually looks very similar to the site that they are impersonating, in order to get you to submit your personal information for purposes of fraud. While this practice is entirely illegal and carries with it severe legal consequences, it is still a very common problem because it is very difficult to police. It is not at all uncommon for IM spammers and phishers to be based in all different parts of the world, many times in nations that are nearly impossible to regulate from the United States (such as Russia and Nigeria). In order to avoid being a victim of phishing, avoid clicking any links sent to you from suspicious users. Most reputable companies (especially Ebay, PayPal and the banks) will never contact you asking for your personal information. If this ever happens, consider it a red flag immediately and report it to the respective company.
As long as you remain wary of unknown users contacting you via instant messaging, you should have no problems and can expect a safe experience using those programs.
