Final answer:
The computer is likely infected with fileless malware, which operates in memory and uses legitimate scripts like PowerShell to execute commands. This type of malware is difficult to detect and requires a comprehensive response strategy.
Step-by-step explanation:
If a security analyst receives a notification of possible malware that used Windows PowerShell to create new malicious processes in the computer's memory, the computer is likely infected with a form of malware known as fileless malware. This type of malware resides primarily in memory and utilizes existing legitimate programs or scripts, like PowerShell, to execute its actions. The attack is particularly concerning because it can often evade detection by conventional antivirus software that scans for files on the disk, as fileless malware leaves fewer traces and may not install new files on the system's hard drive.
Upon identifying that PowerShell was used to generate malicious processes, the security analyst must initiate an incident response protocol, which would typically include isolating the infected machines, conducting a thorough forensic analysis to understand the scope and mechanism of the attack, and then proceeding with the remediation actions to clear the infection and restore any affected systems or data. Beyond immediate response, addressing such threats would also involve updating the organization's cybersecurity strategies, such as improving behavioral-based detection mechanisms and ensuring proper monitoring of the use of administrative tools like PowerShell.