#How does worm virus work software#
#How does worm virus work code#

Others write Word documents purporting to contain passwords for porn sites and infect them with macro viruses.

#How does worm virus work software#

Everyone loves free stuff, and virus writers often infect pirated software in order to spread their work. Social engineering has always played a huge part in spreading viruses. This virus is thought by some to be the most widespread virus infection of all time. This is how the Concept virus of 1995 worked. If the macro is malicious, you're in trouble. Office documents allow you to embed macros written in Word Basic that run automatically when you open the file.

With the rise in popularity of Microsoft Office in the early 1990s, virus programmers began to use another non-resident virus technique.

Finally, the virus hands control to the application as if nothing had happened.Д«ecause of this, reinstalling a fresh copy of an infected application on a system infested with a non-resident virus makes little difference, because it can quickly become reinfected by other applications. It then hands control to the infection propagator, which infects the found executables. When the user starts an infected application, the target locator runs first and finds other executables to infect. These attach themselves to executables and wait for them to be run. Unlike today, early antivirus software didn't always check RAM properly for resident infections before scanning files, so opening executables to scan them could also infect them.ДЄs well as resident viruses, there are also 'non-resident' viruses.

#How does worm virus work code#

Infection itself is handled by code called the 'infection propagator'. When this happens, the target locator knows that the file in question can be infected. The target locator in a resident virus waits for the OS to perform a specific task. The subroutine within Elk Cloner that watched for a new floppy disk insertion is now generally known as a 'target locator' (or sometimes a 'finder module'). This was the virus's 'payload'.Д®LK CLONER: Ironically, one of the first 'viruses' was written for the Apple II With every fiftieth boot of an infected machine, Elk Cloner would display a little poem. When a second user booted his own machine with the copied disk, the virus would run on that system, too. This form of operation makes it a 'resident' virus. When the machine booted up using an infected floppy disk, it would run as part of the operating system and then stay running, watching for the insertion of any subsequent disks. One of the first such viruses was Elk Cloner, which was written in 1981 by a 15-year-old high school student from Pittsburgh, Rich Skrenta.Д®lk Cloner lived in the boot sector of Apple II system disks. When the first modern viruses hit home computers in the 1980s, the infection vector was the boot sector of floppy disks. In a similar way, computer viruses need to be shifted from one place to another by users, accidentally or not. Human viruses such as influenza, for example, require poor hygiene to help them spread. That is, they can't escape the Petri dish and spread by themselves. There's a saying in nursing that 'germs don't jump'.