A computer virus becomes active when its malicious code is executed on a host system, typically triggered by a user's action or a system event.
Here's a breakdown of how a virus goes from dormant to active:
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Initial Infection: The virus first needs to get onto a computer or device. As per the reference, common methods include:
- Opening malicious email attachments: These attachments often contain executable files disguised as documents or images.
- Clicking on infected links: These links might lead to websites that automatically download and execute the virus, or trick the user into doing so.
- Downloading infected files: Downloading software from untrusted sources can expose the device to viruses.
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Execution Trigger: Once on the system, the virus needs a trigger to activate. This trigger is often the user. Some examples:
- Opening the infected file: When a user opens an infected attachment or program, the virus code is executed.
- Running a compromised program: Some viruses attach themselves to legitimate programs. When the program is run, the virus code executes alongside it.
- Booting from an infected drive: In some cases, the virus infects the boot sector of a storage device. When the computer starts, the virus is loaded into memory and becomes active.
- Vulnerabilities in Software: Exploiting security flaws in operating systems or applications can automatically trigger virus execution without requiring explicit user interaction.
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Virus Activity: Once active, the virus can then:
- Replicate itself: It copies its code and spreads to other files, programs, or storage devices.
- Carry out its malicious payload: This could involve:
- Deleting or corrupting files.
- Stealing sensitive information (passwords, credit card details, etc.).
- Displaying unwanted advertisements or messages.
- Turning the computer into a bot to launch attacks on other systems.
- Encrypting files and demanding a ransom (ransomware).
In essence, a virus remains inactive until a specific event causes its malicious code to be executed, at which point it becomes active and begins to carry out its intended purpose. It is crucial to employ strong security measures, such as installing reputable antivirus software and practicing safe browsing habits, to prevent viruses from becoming active in the first place.
