Explanation
Incident management (IM) is a necessary part of a security program. When effective, it mitigates business impact, identifies weaknesses in controls, and helps fine-tune response processes.
In this question, an attack has been identified and confirmed. When a server is compromised or used to commit a crime, it is often necessary to seize it for forensics analysis. Security teams often face two challenges when trying to remove a physical server from service: retention of potential evidence in volatile storage or removal of a device from a critical business process.
Evidence retention is a problem when the investigator wants to retain RAM content. For example, removing power from a server starts the process of mitigating business impact, but it also denies forensic analysis of data, processes, keys, and possible footprints left by an attacker.
A full a bit level image, including RAM should be taken of one or more of the Linux servers. In many cases, if your environment has been deliberately attacked, you may want to take legal action against the perpetrators. In order to preserve this option, you should gather evidence that can be used against them, even if a decision is ultimately made not to pursue such action. It is extremely important to back up the compromised systems as soon as possible. Back up the systems prior to performing any actions that could affect data integrity on the original media.