A Trojan is likely to be more difficult to deal with than a virus

Viruses, worms, Trojan horses and related computer threats are commonly confused with each other because they often cause similar damage. Viruses have been around longer than the others, and consequently the term “virus” is commonly but inaccurately used to refer to all of them. Here are some distinguishing characteristics:

Virus
A virus is a relatively small file that can copy itself into another file or program (its host). It can be transmitted only if its host file or program is transmitted. Some viruses are designed to change themselves slightly in order to make their detection and removal more difficult. Many viruses are merely annoyances, but some can be very destructive. As a whole, they are less common now than in the past. For more information, see the Wikipedia page on Computer virus.

Trojan horse
A Trojan horse is a program that appears to be useful or entertaining, but it carries a hidden malicious function that is activated when the program is run. Some Trojan horses even masquerade as repair tools, claiming to remove threats from your computer but actually doing the opposite. Older Trojan horses could not transmit themselves, but more recent versions can. This blurs the traditional distinction between viruses and Trojan horses. For more information, see the Wikipedia page on Trojan horse (computing)

Worm
A worm is a program that can both copy and transmit itself. This type of threat is now more common and often more disruptive than many viruses. For more information, see the Wikipedia page on Computer worm.

Malicious script
These vary in the harm they can cause, and they can get into your computer or compromise your personal information by a number of means; e.g., when you click on a link inside an specially designed fradulent email or submit a form that has such a script hidden inside it.

How they spread and what they do
Electronic threats are usually spread by opening infected email attachments and by downloading infected files. Clicking on links inside certain emails can result in threats being downloaded to your machine. They can even enter your computer as attachments to Instant Messages. When these threats are being transmitted in large numbers, they can significantly drain network resources and slow down Internet traffic. When one of them infects your computer, it might take one or more of the following actions:

  • Operate silently, with no obvious indication of its presence
  • Remain dormant initially and activate later at a specified time or when you perform a certain action
  • Destroy or corrupt your files
  • Send copies of itself to all of your email contacts, potentially infecting them as well
  • Deactivate your antivirus software
  • Prevent you from using your browser to download virus removal tools
  • Log your keystrokes and steal credit card numbers and passwords when you make purchases or bank online.
  • Hijack your browser and take you to Web sites where you may be fooled into entering personal information such as account passwords
  • Hijack your computer and use it maliciously or commercially, making you appear to be the perpetrator.

What you can do about them
While it is useful to understand the technical distinctions among these threats and important to know what damage they can cause, it is crucial that you maximize your protection against them and minimize their spread to other computer users. It is particularly important to keep the following items updated every few days or as often as the software recommends. You can set many of these programs to have the updating done automatically.

  • Operating system
  • Web browsers
  • Instant Message software
  • Microsoft Office and other applications with known vulnerabilities
  • Antivirus definitions
  • Antispyware

See more on how to protect your personal data.

Go to Safe Computing at NC State.

If you do not take measures to keep your computer safe, your computer -- and you -- could become the target of a cybercrime.

Cybercrimes are those instances when criminals, known as hackers or attackers, access your computer for malicious reasons. You can fall victim any time you are on an unprotected computer, receive a deceptive email claiming there is an “urgent matter” regarding your ISCA account or just surfing the Web. They might be seeking sensitive, personal identification information stored on your computer, like credit card numbers or private account logins they use for financial gain or to access your online services for criminal purposes. Or they could want your computer’s resources, including your Internet connection, to increase their bandwidth for infecting other computers. This also allows them to hide their true location as they launch attacks. The more computers a criminal hides behind, the harder it becomes for law enforcement to figure out where the criminal is. If the criminal can’t be found, he can’t be stopped and prosecuted.

There are many different threats to your computer’s safety, as well as many different ways a hacker could try to steal your data or infect your computer. Once on a computer, the threat will tend to show little to no symptoms so it can survive for a prolonged period undetected. Your online security and cybercrime prevention can be straightforward. In general, online criminals are trying to make their money as quickly and easily as possible. The more difficult you make their job, the more likely they are to leave you alone and move on to an easier target. We’ve compiled a list of the different types of threats that are out there along with some recommended steps you can take to reduce your susceptibility to these threats.

Computer Threat #1: Vulnerabilities

How they attack: Vulnerabilities are flaws in computer software that create weaknesses in your computer or network’s overall security. Vulnerabilities can also be created by improper computer or security configurations. Threats exploit the weaknesses of vulnerabilities, resulting in potential damage to the computer or its data.

How do you know? Companies announce vulnerabilities as they are discovered and quickly work to fix them with software and security "patches."

What to Do

  • Keep software and security patches up to date.
  • Configure security settings for your operating system, Internet browser and security software.
  • Companies should develop personal security policies for online behavior, and individuals should be sure to adopt their own policies to promote online safety.
  • Install a proactive security solution like Norton Internet Security to block threats targeting vulnerabilities.

Computer Threat #2: Spyware

How it attacks: Spyware can be downloaded from Web sites, email messages, instant messages and direct file-sharing connections. Additionally, a user may unknowingly receive spyware by accepting an End User License Agreement from a software program.

How do you know? Spyware frequently attempts to remain unnoticed, either by actively hiding or simply not making its presence on a system known to the user.

What to Do

  • Use a reputable Internet security program to proactively protect from spyware and other security risks.
  • Configure the firewall in the reputable Internet security program to block unsolicited requests for outbound communication.
  • Do not accept or open suspicious error dialogs from within the browser.
  • Spyware may come as part of a "free deal" offer -- do not accept free deals.
  • Always carefully read the End User License agreement at Install time and cancel if other “programs” are being installed as part of the desired program.
  • Keep software and security patches up to date.

Computer Threat #3: Spam

How it attacks: Email spam is the electronic version of junk mail. It involves sending unwanted messages, often unsolicited advertising, to a large number of recipients. Spam is a serious security concern, as it can be used to deliver email that could contain Trojan horses, viruses, worms, spyware and targeted attacks aimed at obtaining sensitive, personal identification information.

How do you know? Messages that do not include your email address in the TO or CC fields are common forms of spam. Some spam can contain offensive language or links to Web sites with inappropriate content. Also, some spam may include hidden text that only becomes visible if you highlight the content -- a common trick spammers use to get their email to pass through spam filters without detection.

What to Do

  • Install Spam filtering/blocking software.
  • If you suspect an email is spam, do not respond -- just delete it.
  • If you suspect an email is spam, do not respond -- just delete it.
  • Reject all Instant Messages from people who are not on your Buddy list.
  • Do not click on URL links within IM unless they are from a known source and expected.
  • Keep software and security patches up to date.

Computer Threat #4: Malware

How it attacks: Malware is a category of malicious code that includes viruses, worms and Trojan horses. Destructive malware will use popular communication tools to spread, including worms sent through email and instant messages, Trojan horses dropped from Web sites and virus-infected files downloaded from peer-to-peer connections. Malware will also seek to exploit existing vulnerabilities on systems making their entry quiet and easy.

How do you know? Malware works to remain unnoticed, either by actively hiding or by simply not making its presence on a system known to the user. You might notice your system is processing at a slower rate than what you are used to.

What to Do

  • Only open email or IM attachments that come from trusted sources and are expected.
  • Have email attachments scanned by a reputable Internet security program prior to opening.
  • Delete all unwanted messages without opening.
  • Do not click on Web links sent by someone you do not know.
  • If a person on your Buddy list is sending strange messages, files or Web site links, terminate your IM session.
  • Scan all files with a reputable Internet security program before transferring them to your system.
  • Only transfer files from well-known sources.
  • Use a reputable Internet security program to block all unsolicited outbound communication.
  • Keep security patches up to date.

Computer Threat #5: Phishing

How it attacks: Phishing is essentially an online con game, and phishers are nothing more than tech-savvy con artists and identity thieves. They use spam, malicious Web sites, email messages and instant messages to trick people into divulging sensitive information, such as bank and credit card information or access to personal accounts.

How do you know? Here are four ways to identify phishing scams:

  • Phishers, pretending to be legitimate companies, may use email to request personal information and instruct recipients to respond through malicious Web sites. They may also claim that an urgent action is needed to lure recipients into downloading malicious programs onto their computers.
  • Phishers tend to use emotional language like scare tactics or urgent requests to entice recipients to respond.
  • Phish sites can look remarkably like legitimate sites, because the criminals tend to use the copyrighted images from genuine sites.
  • Requests for confidential information via email or Instant Message tend to not be legitimate.

After you open and run an infected program or attachment, you might not notice the impacts to your computer right away. Here are a few indicators that might indicate your computer has been infected:

Is a Trojan worse than a virus?

Unlike viruses, Trojan Horses do not replicate themselves, but they can be just as destructive. Trojans also open a backdoor entry to your computer, giving command to malicious actor or allowing malicious users/programs access to your system. This leads to confidential and personal information being stolen.

What is the main difference between a virus and a Trojan?

1. A Virus is a malicious executable code attached to another executable file which can be harmless or can modify or delete data. Trojan Horse is a form of malware that capture some important information about a computer system or a computer network.

Are Trojans hard to get rid of?

Trojan horses are some of the most frustrating viruses that you can get on your computer. Not only are they easy to pick up, they're not always easy to find. On top of that, Trojan horses are irritating to get off of the computer once they're there. However, they're not impossible to remove.

Are Trojan Viruses hard to find?

While there are many types of Trojan horse malware, they're all designed to fool you into installing them. That's why Trojans can be so hard to detect — they look like legitimate software.