Computer virus are programs or parts of code that are installed or run on your computer without your consent, in most cases, due to ignorance.
Malware, is the term used to encompass this type of codes, formed by the union of the words malicious and software. Nowadays they can take any form, from an image, a PDF document or just an internet link, and receive it from anywhere. You can check another article talking about this, https://avertigoland.com/2021/05/real-time-map-of-ddos-attacks/.
The main methods of infection today are:
- Social Networks. Access to infected messages.
- Fraudulent websites.
- Download infected freeware.
- P2P networks (Emule, torrent). Download infected files.
- Malicious applications can be in both the message body and attachments.
- Removable media from USB data storage, CD, etc..
How a virus attack?
Once the virus is added to a program, it will remain inactive until some circumstance causes the computer or device to execute its code. For a virus to infect a computer, the infected program must be run, which will cause the virus code to run. In other words, the virus could remain inactive on your computer, without showing any great signs or symptoms.
However, once the virus infects your computer, it can infect others on the same network. Viruses can perform devastating and annoying actions, for example:
- Steal passwords or data.
- Record keystrokes.
- Damage files.
- Send spam (spam or junk mail)to your contacts
- Take control of your computer.
While some viruses may have a joking aim and effect, others can generate harmful and important results, for example, erasing data or causing permanent damage to the hard drive. Today, however, the vast majority are designed to get personal data and get money.
How does it work?
Once you run the file, the virus code is hosted on your computer infecting it, even if you close the open program the virus will continue to run in the background, then it takes control of the basic services of the operating system, adding that piece of code to other programs or publications on networks or emails.
How do computer virus spread?
Viruses can be spread by attachments in text messages or e-mails, internet file downloads, social media scam links, and even mobile viruses can infect mobile devices and smartphones by downloading suspicious apps.
Ways to classify
There are several ways to classify viruses, I will talk about 3 of them.
Depending on the element they infect
In this case we can talk about:
- Boot or boot sector viruses.
- File or file virus.
- Virus Script.
- Virus macro.
- Multiple Viruses.
- Sobreescritura virus.
Computer virus according to how they carry out attacks
In this case we can talk about:
- Direct acting . These viruses do not remain resident in memory, at the time of execution they try to replicate, they will look for files located in the same directory to infect them. They often need a specific or specific condition to be met in order to take action. Each time they run, they can be installed in a different location with the aim of infecting different files, although they are most commonly located in the root directory.
- Resident. when you run the program or open a document that contains this type of virus it will be hosted in the ram of your computer and will infect all those files and programs that are loaded into ram
Virus depending on the damage they cause or the function for which they were created
We can talk about:
- Time Bomb or TimeBomb. Some viruses became famous, such as ‘Friday the 13th’ and ‘Michelangelo’. They are viruses that are activated at a certain point in time.
- Trojans or Trojan horses.
- Backdoors. It is a backdoor Trojan capable of allowing access to our machine by an intruder.
- Password Stealers.
- Banking Trojan (Trojan-Banker).
- Adware. These are advertising windows.
- Rogue. They are viruses which make you believe that you have a virus to pay for something you don’t need because there is no such threat.
- Los Hijackers.
- Viruses in other media.