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Resident virus

(also memory-resident virus)

Resident virus definition

A resident virus is malware that embeds in the computer memory, enabling it to infect other computer files without even being executed. It does this by loading its replication module into the RAM. In turn, the operating system can trigger it whenever it loads or performs functions, making the memory-resident virus one of the worst types of computer viruses. It can attach to antivirus applications, affect the entire system, and interfere with its regular operation.

Resident virus examples

  • Meve. A memory-resident virus that infects the MBR of the hard drive, disabling the computer from booting.
  • CMJ. A resident virus that infects executable files and can cause slow performance and system crashes.
  • Jerusalem. A virus that infects executable computer files, known for its ability to cause system crashes and display messages on the infected computer’s screen.
  • CMOS De-Animator. A memory-resident virus that affects the CMOS memory of the BIOS and overwrites its contents, causing the computer to display error messages when it’s booting or even failing to boot.

Preventing resident virus attacks

  • Maintain up-to-date, reputable antivirus software.
  • Enable automatic updates for your OS, web browsers, and other software.
  • Avoid visiting unknown links and opening or downloading attachments from unknown sources.
  • Utilize a firewall and restrict unauthorized access to your device.
  • Avoid using admin access daily.