Find sigma rule 
Attack: Valid Accounts: Default Accounts
Adversaries may obtain and abuse credentials of a default account as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Default accounts are those that are built-into an OS, such as the Guest or Administrator accounts on Windows systems. Default accounts also include default factory/provider set accounts on other types of systems, software, or devices, including the root user account in AWS and the default service account in Kubernetes.(Citation: Microsoft Local Accounts Feb 2019)(Citation: AWS Root User)(Citation: Threat Matrix for Kubernetes)
Default accounts are not limited to client machines, rather also include accounts that are preset for equipment such as network devices and computer applications whether they are internal, open source, or commercial. Appliances that come preset with a username and password combination pose a serious threat to organizations that do not change it post installation, as they are easy targets for an adversary. Similarly, adversaries may also utilize publicly disclosed or stolen Private Keys or credential materials to legitimately connect to remote environments via Remote Services.(Citation: Metasploit SSH Module)
MITRE
Tactic
- privilege-escalation
- defense-evasion
- persistence
- initial-access
technique
- T1078.001
Test : Enable Guest account with RDP capability and admin privileges
OS
- windows
Description:
After execution the Default Guest account will be enabled (Active) and added to Administrators and Remote Desktop Users Group, and desktop will allow multiple RDP connections.
Executor
command_prompt
Sigma Rule
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proc_creation_win_susp_add_user_remote_desktop_group.yml (id: ffa28e60-bdb1-46e0-9f82-05f7a61cc06e)
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proc_creation_win_net_execution.yml (id: 183e7ea8-ac4b-4c23-9aec-b3dac4e401ac)
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proc_creation_win_susp_local_system_owner_account_discovery.yml (id: 502b42de-4306-40b4-9596-6f590c81f073)
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proc_creation_win_net_user_add.yml (id: cd219ff3-fa99-45d4-8380-a7d15116c6dc)
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registry_set_terminal_server_tampering.yml (id: 3f6b7b62-61aa-45db-96bd-9c31b36b653c)