What it is
An internet worm is self-spreading malware that copies itself across networks without you clicking or installing anything. Unlike a classic virus that needs an infected file to run, a worm exploits bugs and weak settings to move automatically from one device to the next.
How it spreads - quick tour
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Scans the internet or local network for known vulnerabilities
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Uses default passwords or misconfigurations to slip in
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Drops a loader, then propagates to new targets from the infected host
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Can add payloads like ransomware or cryptominers once inside
What you may notice
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Sudden network slowdowns or bandwidth spikes
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Services crashing or machines rebooting unexpectedly
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New firewall rules or admin accounts you did not create
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Security alerts about blocked exploit attempts across many hosts
If it hits - first moves
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Isolate affected systems from the network.
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Patch the exploited vulnerability on all hosts before reconnecting.
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Run a full anti-malware scan and remove persistence tasks or services.
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Rotate admin passwords and keys from a clean machine.
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Review logs to confirm containment and find patient zero.
Prevent it
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Patch fast on internet-facing apps, VPNs, and OS services
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Disable or restrict unused ports and services
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Enforce strong, unique passwords and MFA for admin access
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Segment networks and apply egress filtering to limit spread
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Use EDR and IDS/IPS to spot scanning and exploitation early
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Keep backups offline and test restores