Do you know how they hacked your account? Part four: Viruses

In this part we will highlight some of the well-known types of computer viruses

1. Trojan
   A Trojan horse (commonly known as a Trojan) is a type of malware that conceals itself as a normal file or program to trick you into downloading and installing malware.A Trojan can do many dangerous things to your system, like give cyber criminals unauthorized, remote access to your infected computer.Once that happens, cyber criminals can:

• steal data (logins, financial data, even electronic money),
• install more malware, modify files,
• monitor your activity (screen watching, key logging, etc.),
• use the computer in botnets (a collection of Internet-connected programs communicating with other similar programs in order to spread malware),
• encrypt your files, like in the case of ransomware
• crash your computer
• format your disks, destroying all the contents on your device, etc.

  HOW YOU CAN GET INFECTED: There are plenty of ways in which your system can become compromised by a Trojan:

• through email attachments
• software or music downloads
• unsafe instant messages
• peer 2 peer downloads
• routine forms that need to be filled in
• drive-by downloads, etc.

2. Virus (Computer Virus)
   A computer virus (shortly called virus) is a type of malware (told you it would come up often!) capable of replicating itself and spreading to other computers and data files.Viruses spread to other computers by attaching themselves to various programs and executing code when you launch one of those infected programs.But they’re really sneaky, so they can also spread through script files, documents, and cross-site scripting vulnerabilities in web apps.
   Viruses are also evil, because they can be used to steal information, harm your computers, log keystrokes , create botnets, spam your contacts, steal your money, display political or humorous messages on your screen (the least of your worries), and more.
   
   HOW YOU CAN GET INFECTED:
   Viruses install themselves without your consent, because cyber criminals use social engineering and exploit software bugs and vulnerabilities  to gain access to your computing resources.
   Viruses can reside in executable files (.exe or .com files), in data files (Microsoft Word documents or PDFs), or in the boot sector of your hard drive. Or in a combination of all of these.
   And the worst part is that some viruses are polymorphic, which means that the virus has no parts which remain identical between infections, making it very difficult to detect directly with an antivirus solution.
3. Zero-Day virus          
   Zero-Day viruses appear when cyber criminals discover a flaw in a piece of software (for example, in Adobe Air). They exploit that vulnerability, launching an attack that users can’t defend themselves against, for two simple reasons:

• The flaw they exploit is attacked by launching a previously unknown computer virus or other malware
• Antivirus programs rely upon signatures to identify malware, but the signature for this new breed of malware or virus is not in their database, because it’s new and hasn’t been sampled.

  That is why antivirus software is not effective against Zero-Day viruses, and that why you need additional solutions to protect you from advanced attacks such as these.

  HOW YOU CAN GET INFECTED: The usual methods described beforehand work in this case as well:

• drive-by downloads
• malvertising
• spam
• through email attachments
• software or music downloads
• unsafe instant messages
• peer 2 peer downloads
• routine forms that need to be filled in, etc.

The difference is that, once you get infected, there’s very little you’ll be able to do to stop the infection and mitigate its effects.