Suspicious Curl Download to Update Executable during FortiClient EMS Exploitation

ATT&CK techniques

C2

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
- T1105Ingress Tool Transfer
- T1219Remote Access Tools
Exfiltration
Impact

What it detects

This rule detects curl downloading a remote file to C:\update.exe, a staging step observed after FortiClient EMS exploitation to fetch a ScreenConnect remote-access installer. Writing a downloaded binary to a generic update path in the drive root disguises tooling as a software update. This ingress pattern indicates remote payload delivery.

Reporting behind it

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Suspicious Curl Download to Update Executable during FortiClient EMS Exploitation

Pivot detection · T1105 · 9 related

Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.

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