Difference between a virus and a Trojan

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

A computer virus attaches itself to a program or file enabling it to spread from one computer to another, leaving infections as it travels. Like a human virus, a computer virus can range in severity: some may cause only mildly annoying effects while others can damage your hardware, software or files. Almost all viruses are attached to an executable file, which means the virus may exist on your computer but it actually cannot infect your computer unless you run or open the malicious program. It is important to note that a virus cannot be spread without a human action, (such as running an infected program) to keep it going.

A Trojan Horse is full of as much trickery as the mythological Trojan Horse it was named after. The Trojan Horse, at first glance will appear to be useful software but will actually do damage once installed or run on your computer. Those on the receiving end of a Trojan Horse are usually tricked into opening them because they appear to be receiving legitimate software or files from a legitimate source. When a Trojan is activated on your computer, the results can vary. Some Trojans are designed to be more annoying than malicious (like changing your desktop, adding silly active desktop icons) or they can cause serious damage by deleting files and destroying information on your system. Trojans are also known to create a backdoor on your computer that gives malicious users access to your system, possibly allowing confidential or personal information to be compromised. Unlike viruses and worms, Trojans do not reproduce by infecting other files nor do they self-replicate.

2. A virus or malware can impact which of the three tenets of information systems security (confidentiality, integrity, or availability)? In what way? Viruses can send files to other people that don’t allow them to read these files, which affects confidentiality. Some viruses can break programs, affecting availability. Some viruses will change files in a program, which impacts integrity.

3. Why is it recommended to do an anti-virus signature file update before performing an anti-virus scan on your computer?

Signature files contain the latest list and behavior of known viruses. Anti-virus programs release signature file updates regularly sometimes daily, sometimes more often because new viruses are being identified on a daily basis. It is best to configure your anti-virus program to automatically check for updates these updates.

4. Why might your co-worker suggest encrypting an archive file before e-mailing it?

Any computer that handles any sensitive information should require encryption.

5. What kind of network traffic can you filter with the Windows Firewall with Advanced Security?

Inbound rules – they apply to traffic that is coming from the network or the Internet to your Windows computer or device. For example, if you are downloading a file through BitTorrent, the download of that file is filtered through an inbound rule. Outbound rules – these rules apply to traffic that is originating from your computer and going to the network and the Internet. For example, your request to load the How-To Geek website in your web browser is outbound traffic and it is filtered through an outbound rule. When the website is downloaded and loaded by your browser, this is inbound traffic. Connection security rules –less common rules that are used to secure the traffic between two specific computers while it crosses the network. This type of rule is used in very controlled environments with special security requirements. Unlike inbound and outbound rules, which are applied only to your computer or device, connection security rules require both computers involved in the communication to have the same rules applied.

6. What are typical indicators that your computer system is compromised?

When you start your computer, or when your computer has been idle for many minutes, your Internet browser opens to display Web site advertisements. When you use your browser to view Web sites, other instances of your browser open to display Web site advertisements. Your Web browser’s home page unexpectedly changes.

Web pages are unexpectedly added to your Favorites folder.
New toolbars are unexpectedly added to your Web browser.
You cannot start a program.
When you click a link in a program, the link does not work. Your Web browser suddenly closes or stops responding.
It takes a much longer time to start or to resume your computer. Components of Windows or other programs no longer work.

7. What elements are needed in a workstation domain policy regarding use of anti-virus and malicious software prevention tools?

Policies for workstation antivirus and malicious software prevention tools must be consistent. They have to be the same for all computers in the network or it won’t do any good.