In computing, a computer virus is a malicious program developed by programmers that infects a computer with the purpose of the device perform a certain action, usually surreptitiously and without the user’s knowledge. It can damage the file system, steal or hijack information or make copies of itself and try to spread to other computers using various means.
From this point, this article will discuss this important issue, which should not be in any way taken lightly, because we can be victims of a truly difficult situation.
One of the first known viruses, the boot viruses infect the operating system boot partition. The virus is activated when the computer is turned on and the operating system is loaded.
Time Bomb or Time Bomb
The virus known as “Time bomb” are scheduled to be triggered at certain times, defined by its creator. Once it infected a certain system, the virus will activate and only cause damage on predefined date. Some viruses became famous as “Friday the 13th” and “Michelangelo”.
In order to create virus from spreading as quickly as possible, the developers sometimes leave aside the possibility of damaging the system for the virus to replicate faster, and therefore do their job more efficiently. In this way its creators take greater visibility on the Internet.
This type of virus became increasingly perfect, there is a version that in attacking a computer, not only replicates, it also spreads via the Internet by sending the e-mails registered in the e-mail client such as Thunderbird and others, infecting other computers when users open these emails, restarting the cycle.
Trojans or Trojan horses
Certain viruses bring inside a separate code, which allows a person access the infected device to collect data and send it over the Internet to a stranger, without the user’s knowledge of this computer.
These codes are called Trojans or Trojan horses. Initially, Trojan horses allowed infected computer could receive external commands, without the user’s knowledge. Thus the invader could read, copy, delete and alter system data.
Trojan horses currently watch the infected PC to steal confidential user data, such as bank passwords. In the past, viruses were the most important way to enter a Trojan to a PC, taking advantage of its high capacity for replication.
Today, Trojan horses do not need a virus to gain access to a PC, it is sufficient that the user downloads a file from the Internet and run. This practice is very effective, because of the huge amount of fraudulent e-mails that come to the user mailboxes.
These e-mails usually contain a web address to download, without user consent, the Trojan horse, instead of a legitimate file. This practice is called phishing.
Currently, most banking Trojans simulate webs, “fishing” the password typed by users of infected computers. Fortunately there are different ways to know if you are infected with a Trojan and how to eliminate it from your PC.
The hijackers are programs or scripts that “kidnap” Internet browsers, primarily Internet Explorer. However, other browsers without updating or unprotected can also fall into the trap. When that happens, the hijacker changes the browser home page and prevents users from changing displays advertising pop-ups or new windows, install toolbars in the browser and can prevent access to certain sites (such as antivirus software sites, for instance).
Basically, a keylogger is software that is capable of record the keystrokes of the user, storing them in a file and then send to your developer. After they are executed, usually keyloggers are hidden in the operating system, so that the victim does not aware of this being watched.
Keyloggers currently are developed for illicit purposes, such as stealing bank passwords. These keyloggers are also used by more advanced users to obtain personal passwords, such as email accounts and chat accounts, among others.
There are types of keyloggers that capture the screen of the victim, with the purpose of knowing everything the victim is doing on your computer, giving the attacker a simpler way of knowing that stealing.
The zombie state occurs when a computer is infected and is being controlled by other people. In this manner can be used to spread viruses, keyloggers, and others invasive procedures.
Usually this situation occurs because the computer has a firewall and / or operating system outdated. According to studies, a computer that is on the Internet in these conditions has almost a 50% chance of becoming a zombie machine, usually for criminal purposes.
Macro viruses are one of the most dangerous virus types, but nevertheless goes almost unnoticed for all users who develop their activities using software such as Microsoft Office suite. The so-called macro viruses are a type of malware that is designed to run on those little scripts known as macros, very common in office software suites, and are used to automate or to get easier tasks that would otherwise be much more complex performing.
These macros are used by virus writers to include code that when executed, allows to attacker open a door that is used to steal information, or infect through expansion into other system files with illegal objectives.
New devices, new problems
There is much talk of prevention against computer viruses on personal computers, but few people know that today many of the devices have internet access. This includes mobile phones, handhelds, tablets, notebooks, VoIP phone, Mp3 Players and much more devices.
At present there are viruses that can affect performance and damage this devices, and are not isolated cases. With the large number of communications and entertainment devices on the market today, it was only a matter of time before hackers and developers begin to dump their efforts in trying to break the safety of these devices.
Fortunately, big companies learned the lesson and today operating systems such as Android and iOS are much safer, and include file protection systems through permission.