Network Security Threats

Viruses and Worms

The term virus has long been used generically to describe any computer threat, but in actuality it refers specifically to malware that inserts malicious code into existing documents or programs, and then spreads itself by various means.

Trojan Horses

A Trojan horse is a malware attack that disguises itself as something innocent, such as a computer game, or a YouTube search results page. A recent example of a devastating Trojan horse used an email with a link that supposedly connected the reader to a video of the Saddam Hussein hanging, but instead just infected them with malware. Once installed on a computer, the 'Saddam' Trojan horse then downloaded and installed a keylogger onto the infected computer. This keylogger was used to record every keystroke by a computer’s user, thus stealing financial account information and passwords.

Spam

Depending on the source cited, spam makes up 70 to 84 percent of daily emails sent throughout the world. All that spam results in billions of dollars in lost productivity and creates an ever increasing need for IT resources to filter out this irritating and potentially malicious menace.

Phishing

Anyone who has ever used PayPal or does their banking online has probably received dozens of emails with titles such as, "URGENT: Update Account Status". These emails are all attempts by a spammer to "phish" your account information. Phishing refers to spam emails designed to trick recipients into clicking on a link to an insecure website. Typically, phishing attempts are executed to steal account information for e-commerce sites such as eBay, payments processors such as PayPal, or regular financial institutions' websites. A phishing email supplies you with a link to click on, which will take you to a page where you can re-enter all your account details, including credit card number(s) and/or passwords. Of course, these sites aren't the actual bank's site, even though they look like it.

Packet Sniffers

Packet sniffers capture data streams over a network, thus allowing for the capture of sensitive data like usernames, passwords and credit card numbers. The result, unsurprisingly, is the loss of data, trade secrets, or online account balances. For network managers specifically, even bigger losses can come from lawsuits due to noncompliance of data protection regulations.

Maliciously-Coded Web sites

Maliciously-coded Web sites can take many different forms, from installing Trojan horses to redirecting you to an unrequested site. But one of the most threatening forms of maliciously-coded websites, those that are designed to steal passwords, are on the rise [4]. A very common form of these Web sites takes advantage of human's charitable instincts by setting up traps in what appear to be sites that allow you to make donations to victims of natural disasters such as Hurricane Katrina. Hackers set up a fake sign-in page, and then encourage unsuspecting victims to enter their credit card number and other personal information.

In addition to stealing personal information, maliciously-coded websites are also often designed for the following purposes:

• installation of keyloggers
• adware/ spyware/ reading cookies
• drive-by downloads
• XSS - cross--site scripting to utilize web browser flaws for other intentions.

Password Attacks

A 'Password Attack' is a general term that describes a variety of techniques used to steal passwords to accounts.

• Brute-force. One of the most labor intensive and unsophisticated methods hackers use to steal passwords is to try to guess a password by repeatedly entering in new combinations of words and phrases compiled from a dictionary. This 'dictionary attack' can also be used to try to guess usernames as well, so developing difficult to guess usernames and passwords is increasingly vital to network security.

• Packet sniffers. As discussed above, Packet Sniffers glean data electronically from a compromised network.

• IP-spoofing. Similar to 'Honeypots', this attack involves the interception of data packets by a computer successfully pretending to be a trusted server/ resource.
• 
  
• Trojans. Trojans are actually invasive, as discussed above, and of these methods, are the most likely to be successful, especially if they install keyloggers.

Shared Computers

In the IT community, it is often said that shared computers are like public bathrooms, they may appear clean, but are usually chock full of viruses. Thankfully, the danger of shared computers is one network threat that you can largely render harmless by limiting the activities that you and your employees perform.