Adversaries may obtain and abuse credentials of a domain account as a means of gaining Initial Access, Persistence, Privilege Escalation, or Defense Evasion. Domain accounts are those managed by Active Directory Domain Services where access and permissions are configured across systems and services that are part of that domain. Domain accounts can cover users, administrators, and services.
Adversaries may compromise domain accounts, some with a high level of privileges, through various means such as OS Credential Dumping or password reuse, allowing access to privileged resources of the domain.
Integrating multi-factor authentication (MFA) as part of organizational policy can greatly reduce the risk of an adversary gaining control of valid credentials that may be used for additional tactics such as initial access, lateral movement, and collecting information. MFA can also be used to restrict access to cloud resources and APIs.
|Privileged Account Management
Audit domain account permission levels routinely to look for situations that could allow an adversary to gain wide access by obtaining credentials of a privileged account. Do not put user or admin domain accounts in the local administrator groups across systems unless they are tightly controlled and use of accounts is segmented, as this is often equivalent to having a local administrator account with the same password on all systems. Follow best practices for design and administration of an enterprise network to limit privileged account use across administrative tiers. Limit credential overlap across systems to prevent access if account credentials are obtained.
Applications may send push notifications to verify a login as a form of multi-factor authentication (MFA). Train users to only accept valid push notifications and to report suspicious push notifications.
|Logon Session Creation
Monitor for suspicious account behavior across systems that share accounts, either user, admin, or service accounts. Examples: one account logged into multiple systems simultaneously; multiple accounts logged into the same machine simultaneously; accounts logged in at odd times or outside of business hours. Activity may be from interactive login sessions or process ownership from accounts being used to execute binaries on a remote system as a particular account.
A remote desktop logon, through Remote Desktop Protocol, may be typical of a system administrator or IT support, but only from select workstations. Monitoring remote desktop logons and comparing to known/approved originating systems can detect lateral movement of an adversary.
Multiple users logged into a single machine at the same time, or even within the same hour, do not typically occur in networks we have observed.Logon events are Windows Event Code 4624 for Windows Vista and above, 518 for pre-Vista. Logoff events are 4634 for Windows Vista and above, 538 for pre-Vista. Logon types 2, 3, 9 and 10 are of interest. For more details see the Logon Types table on Microsoft’s Audit Logon Events page.
Analytic 1 - Remote Desktop Logon
Analytic 2 - Simultaneous Logins on a Host
|Logon Session Metadata
Correlate other security systems with login information (e.g., a user has an active login session but has not entered the building or does not have VPN access).
|User Account Authentication
Monitor for an attempt by a user to gain access to a network or computing resource, often by the use of domain authentication services, such as the System Security Services Daemon (sssd) on Linux