A cybersecurity incident response team at a large company receives notification that malware is present...

The first step in responding to a cybersecurity incident, particularly when malware is detected, is to contain the impacted hosts. This action prevents the spread of malware to other parts of the network, limiting the potential damage while further investigation and remediation actions are planned.

References = CompTIA Security+ SY0-701 study materials, particularly on incident response procedures and the importance of containment in managing security incidents​​.