Account Lockout Policy - A possible threat

Most companys use an account lockout policy for their directory service like Microsoft Active Directory, LDAP-system, eDirectory or their own environment solution. Locking out accounts is helpful when it comes to password guessing attacks like brute force (https://attack.mitre.org/techniques/T1110/) or similar ones.

However: An attacker is able to use lockout policies, too.

The following scenario is not so old, but was already used in the last two years:
1. Attacker gains access to environment
2. Attacker creates its own administrative accounts
3. Attacker brute forces all other administrative accounts
👉This way, the attacker makes sure, that all legitime administrators are locked out.

This is an advanced threat and a not very common attack, yet. The solution for this is to make sure, that not all accounts are affected by the lockout policy. Instead very few dedicated emergancy accounts, which are normally not used and stored in a safe location, should be excluded from it. Those accounts (as all administrative accounts) should be monitored closely in your SIEM or logging systems.