There are several ways to gain SYSTEM-level access on a host, including but not limited to:

• Remote Windows exploits such as MS08-067, EternalBlue, or BlueKeep.
• Abusing a service running in the context of the SYSTEM account, or abusing the service account SeImpersonate privileges using Juicy Potato. This type of attack is possible on older Windows OS' but not always possible with Windows Server 2019.
• Local privilege escalation flaws in Windows operating systems such as the Windows 10 Task Scheduler 0-day.
• Gaining admin access on a domain-joined host with a local account and using Psexec to launch a SYSTEM cmd window

By gaining SYSTEM-level access on a domain-joined host, you will be able to perform actions such as, but not limited to:

• Enumerate the domain using built-in tools or offensive tools such as BloodHound and PowerView.
• Perform Kerberoasting / ASREPRoasting attacks within the same domain.
• Run tools such as Inveigh to gather Net-NTLMv2 hashes or perform SMB relay attacks.
• Perform token impersonation to hijack a privileged domain user account.
• Carry out ACL attacks.