Default Accounts

What the technique is

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, the root user account in ESXi, and the default service account in Kubernetes. Default accounts are not limited to client machines; rather, they 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. Default accounts may be created on a system after initial setup by connecting or integrating it with another application. For example, when an ESXi server is connected to a vCenter server, a default privileged account called vpxuser is created on the ESXi server. […]

What MITRE says you would watch

• AN1283

  Detection of default account usage such as Guest or Administrator performing interactive or remote logons on systems outside of installation or maintenance windows.

• AN1284

  Monitoring for SSH logins from default accounts such as 'root', especially when login is via password and not key-based authentication.

• AN1285

  Use of known default service accounts or root-level cloud accounts performing authentication or changes to IAM policy.