Definition:
A computer virus is a type of malicious software that, when executed, replicates itself by modifying other computer programs and inserting its own code. It often spreads to other computers through files or documents that are shared or downloaded.
Key Points:
Propagation:
- File Infectors: Infect executable files or scripts.
- Macro Viruses: Target macros within documents (e.g., Microsoft Word or Excel).
- Boot Sector Viruses: Infect the master boot record of a hard drive or removable device.
Transmission:
- Email Attachments: Infected files sent as email attachments.
- Downloads: Downloading malicious software or files from untrustworthy sources.
- Removable Devices: USB drives or CDs that contain infected files.
- Web Links: Clicking on malicious links or visiting compromised websites.
Symptoms:
- Slow Computer Performance: Unusual slowdown of the system.
- Unexpected Pop-ups: Frequent pop-up ads or messages.
- Unwanted System Behavior: Programs opening or closing unexpectedly.
- Unrecognized Programs: New, unknown software appearing on the device.
- File Corruption: Files becoming inaccessible or corrupted.
Protection:
- Antivirus Software: Use reliable antivirus solutions that are regularly updated.
- Firewalls: Block unauthorized access to your computer.
- Software Updates: Keep all software, especially the operating system, up-to-date.
- Safe Practices: Avoid opening email attachments from unknown senders or downloading files from suspicious websites.
Removal:
- Full System Scan: Use antivirus software to scan and clean the entire system.
- Quarantine or Delete: Infected files should either be isolated or removed.
- System Restore: Return the computer to a previous state, before the virus infection.
Notable Viruses:
- ILOVEYOU (2000): Spread via email and targeted Microsoft Outlook.
- Code Red (2001): Exploited Microsoft IIS servers.
- Slammer/Sapphire (2003): Caused a significant internet slowdown.
- Conficker (2008): Targeted Windows OS and exploited weaknesses in the OS.
Challenges:
- Polymorphic Viruses: Change their appearance with each infection, making detection challenging.
- Armored Viruses: Designed to make disassembling difficult for analysts.
- Stealth Viruses: Hide from antivirus software by intercepting its requests to the operating system.
Conclusion:
Computer viruses are continually evolving, posing a persistent threat to individual users and organizations. Vigilance, combined with the use of trusted security solutions and safe computing habits, remains crucial in defending against these malicious entities.