A resident virus is a type of malware that embeds itself in a computer's memory and remains active, even after the original infected program is no longer running. It's called "resident" because it "resides" in the RAM.
Here's a more detailed breakdown:
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Persistence: Unlike non-resident viruses that infect files and then terminate, a resident virus stays active in the system's memory. This allows it to infect other files that are accessed or executed.
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Stealth: These viruses often employ techniques to hide their presence, making them difficult to detect by traditional antivirus software. They might attach themselves to system processes or anti-virus applications themselves, allowing them to infect files even when they're scanned.
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Infection Mechanism: When a resident virus is loaded into memory, it can intercept system calls related to file access. Whenever the operating system tries to open, execute, or copy a file, the resident virus can insert its malicious code into that file.
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Impact: Resident viruses can cause a wide range of problems, including:
- File corruption
- System instability
- Data theft
- Performance degradation
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Example scenario: Consider a resident virus attaching itself to an antivirus program. Each time the antivirus program scans a file, the virus has the opportunity to infect that file, even if the original source of the infection has been removed.
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Detection and Removal: Due to their stealth and persistent nature, resident viruses can be challenging to remove. Specialized anti-malware tools, boot-time scans, and even manual removal techniques might be required. Keeping your antivirus definitions updated is crucial.
In summary, a resident virus is a dangerous type of malware that resides in memory and persistently infects files, often evading detection and causing significant damage to a computer system.
