How to Know If a Threat Actor Has Accessed Your Server

The article explains how to spot signs that a server has been compromised and when suspicious activity becomes evidence of unauthorized access.

Common warning signs include abnormal logins, new or backdoor accounts, unexpected processes, and changes to system files or configs.

Suspicious SSH/RDP activity, privilege escalation via sudo or wheel, and altered systemd, PAM, or sshd_config files can indicate deeper compromise.

Unusual network traffic, API token abuse, reverse shells, webshells, cryptominers, and C2 connections are strong indicators of malicious control.

Detecting compromise early helps limit data theft, stop persistence, and reduce the impact before attackers fully take over.