Virus

A computer virus is a type of malicious software (malware) that attaches itself to legitimate programs or files and spreads by infecting other files or systems. Viruses require user action to execute and propagate, such as opening an infected file or running a compromised program.

How Viruses Work

• Infection: Virus code is inserted into a host file or program
• Activation: User executes the infected file, triggering the virus
• Replication: Virus spreads to other files, programs, or systems
• Payload: May delete data, corrupt files, or perform other malicious actions

Types of Viruses

• File Infector: Attaches to executable files
• Macro Virus: Infects documents with macros (e.g., Word, Excel)
• Boot Sector Virus: Infects the master boot record of storage devices
• Polymorphic Virus: Changes its code to evade detection
• Metamorphic Virus: Rewrites its own code with each infection

Symptoms of Infection

• Slow system performance
• Unexpected error messages
• Corrupted or missing files
• Frequent crashes or reboots

Prevention and Detection

1. Use Antivirus Software: Regularly update and scan systems
2. Patch Systems: Keep operating systems and applications up to date
3. User Awareness: Educate users about safe computing practices
4. Backup Data: Maintain regular backups to recover from infections

Incident Response

• Isolate infected systems
• Remove the virus using security tools
• Restore from clean backups
• Investigate the source and method of infection

Related Concepts

• Worm: Self-replicating malware
• Trojan: Disguised malware
• Antivirus: Detection and removal tool

Conclusion

Viruses remain a significant threat to individuals and organizations. Prevention, detection, and user education are key to minimizing the risk and impact of virus infections.