Definition:
A computer worm is a standalone malware that replicates itself in order to spread to other computers. Unlike a virus, it does not need to attach itself to a program or file and doesn’t require human intervention to propagate.

Key Points:

Propagation:

  • Self-replicating: Worms can duplicate themselves without a host program.
  • Network Exploitation: Often use vulnerabilities in networks to spread.
  • Email: Can send copies of themselves to all contacts in an email client.

Transmission:

  • Network Protocols: Can exploit vulnerabilities in protocols like SMB.
  • Instant Messaging: Can spread via links or files sent over IM.
  • File-sharing Platforms: Sharing infected files unknowingly.

Symptoms:

  • Network Congestion: High network activity due to mass replication.
  • Decreased Performance: Consumes system’s resources.
  • Unauthorized Emails: Sending out mass emails without user’s knowledge.
  • File Modifications: Some worms may alter or delete files.

Protection:

  • Firewalls: Block unauthorized access and contain worm’s spread.
  • Regular Patching: Ensure software and OS are updated to close vulnerabilities.
  • Antivirus and Anti-malware: Use solutions that detect and remove worms.
  • Safe Practices: Avoid clicking on unknown links or downloading suspicious attachments.

Removal:

  • Disconnect from Network: Prevents further spread.
  • Scan and Clean: Use trusted security solutions to detect and eliminate the worm.
  • Patch Vulnerabilities: Update software to ensure worm cannot exploit the same vulnerability again.

Notable Worms:

  • Morris Worm (1988): One of the first worms to spread across the internet, it exploited vulnerabilities in UNIX.
  • Code Red (2001): Targeted Microsoft IIS web servers and defaced websites.
  • Blaster (2003): Exploited a Windows vulnerability, causing network congestion.
  • Conficker (2008): Utilized various methods to spread and infected millions of computers.

Challenges:

  • Rapid Spread: Due to autonomous replication, worms can spread extremely quickly.
  • Zero-Day Exploits: Worms using unknown vulnerabilities are difficult to defend against until patches are released.
  • Payload Delivery: Some worms carry payloads, like backdoors, turning infected systems into botnets.

Conclusion:
Worms represent a significant threat due to their ability to spread rapidly and autonomously across networks. Continuous monitoring, updating systems, and adhering to best practices are essential in combating and mitigating the impact of worms.