A computer virus doesn't technically activate "on its own" but rather through the execution of a host program it has infected.
The Mechanism of Virus Activation
Here's a breakdown of how a virus gets its code running:
- Infection: A virus first needs to infect a host program. This typically happens when you download an infected file, visit a compromised website, or open a malicious email attachment.
- Code Insertion: As stated in the provided reference, "The virus writes its own code into the host program". This means the virus’s malicious code is embedded within the program's existing code.
- Execution Trigger: When the user runs the infected host program, the virus's code is executed first. This happens because the virus usually modifies the entry point of the host program to point towards its code.
- Activation and Damage: Once the virus code runs, it can perform its intended malicious actions, such as:
- Replicating itself and infecting other files.
- Deleting or corrupting files.
- Stealing personal data.
- Slowing down your computer's performance.
Why It's Not "On Its Own"
The key point is that a user action is required to execute the infected host program. The virus can’t do anything unless that program runs.
Summary Table
| Action | Description |
|---|---|
| Infection | Virus inserts its code into a host program. |
| Execution | User runs the infected host program. |
| Activation | The virus code executes first before the host program, enabling the virus to perform malicious actions. |
| Impact | Virus replicates, damages files, steals data, etc. |
Example Scenario
Imagine you download a seemingly harmless game from a shady website. This game, unbeknownst to you, is infected with a virus.
- Infection: The virus code has been embedded inside the game's executable file.
- Execution: When you double-click to open the game, the virus code runs before the game's regular code.
- Activation: The virus activates itself by replicating and attempting to infect other programs or perform its other defined malicious actions.
Key Takeaway
While a virus can replicate and spread without further explicit user actions, its initial activation requires the execution of the infected host program, which a user must initiate. Thus, it's not truly on its own but a chain of programmed events following user execution of an infected program.
