Stealth virus (computers)

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In computer science, a stealth virus is a file virus, that uses special techniques to hide its presence from users and virus scanners. This is achieved by intercepting the read request to the file and returning the content of the original read request to the uninfected file.Once the computer has been infected, the virus can make modifications to allow the computer to appear that it has not lost any memory and/or that the file size has not changed.

When an antivirus program tries to detect the virus, the stealth virus feeds the antivirus program a clean image of the file or boot sector.