Clear it in 3 steps
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Start the environment
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Investigate the target
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Submit the flag
Analyze the network-connection record `netstat_dump.txt` to identify the suspicious C&C connection. The single ESTABLISHED connection to a public IP on a non-standard port holds the flag.
Focus on ESTABLISHED connections
Find the one whose remote is a public IP on a non-standard port (not 80/443)
That single connection is the C2 link, and its line holds the flag