What it is
Remcos is a Windows remote access tool (RAT) sold by Breaking Security that’s widely abused by threat actors. Once on a system, it gives remote control: keylogging, screen capture, file exfiltration, command execution, and persistence. Campaigns often deliver it through phishing attachments or cracked software. Background and removal notes: https://gridinsoft.com/threats/remcos
Why it matters
A live RAT means the attacker can watch, steal, and act in real time - from grabbing credentials to deploying more malware or moving laterally.
How it works
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Entry: phishing docs/archives with scripts or droppers; sometimes exploit kits.
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Establish: drops into AppData/ProgramData, sets Run keys or Scheduled Tasks.
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Control: beacons to a C2, receives commands, records keys/screens, and exfiltrates data.
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Expand: downloads additional payloads (stealers, ransomware) as instructed.
Red flags
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Suspicious tasks or Run keys launching random-named EXEs from user folders.
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Firewall prompts for unknown apps; steady outbound to dynamic DNS or unusual ports.
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EDR detections for keylogging, clipboard grabs, or screen capture APIs.
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New archives/scripts arriving via email right before symptoms start.
Prevent it
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Block macro-enabled docs and executable attachments; use attachment sandboxing.
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Enforce phishing-resistant MFA; reset passwords and revoke sessions from a clean device after cleanup.
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Monitor for new Scheduled Tasks, Run keys, and unusual outbound connections.
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Keep systems patched and run reputable anti-malware; isolate and reimage if integrity is uncertain.