NIST-AC-7 Unsuccessful Logon Attempts

a. Enforce a limit of [Assignment: number] consecutive invalid logon attempts by a user during a [Assignment: time period] ; and b. Automatically [Selection (one or more of): lock the account or node for {{ insert: param, ac-07_odp.04 }} ; lock the account or node until released by an administrator; delay next logon prompt per {{ insert: param, ac-07_odp.05 }} ; notify system administrator; take other {{ insert: param, ac-07_odp.06 }} ] when the maximum number of unsuccessful attempts is exceeded.

The need to limit unsuccessful logon attempts and take subsequent action when the maximum number of attempts is exceeded applies regardless of whether the logon occurs via a local or network connection. Due to the potential for denial of service, automatic lockouts initiated by systems are usually temporary and automatically release after a predetermined, organization-defined time period. If a delay algorithm is selected, organizations may employ different algorithms for different components of the system based on the capabilities of those components. Responses to unsuccessful logon attempts may be implemented at the operating system and the application levels. Organization-defined actions that may be taken when the number of allowed consecutive invalid logon attempts is exceeded include prompting the user to answer a secret question in addition to the username and password, invoking a lockdown mode with limited user capabilities (instead of full lockout), allowing users to only logon from specified Internet Protocol (IP) addresses, requiring a CAPTCHA to prevent automated attacks, or applying user profiles such as location, time of day, IP address, device, or Media Access Control (MAC) address. If automatic system lockout or execution of a delay algorithm is not implemented in support of the availability objective, organizations consider a combination of other actions to help prevent brute force attacks. In addition to the above, organizations can prompt users to respond to a secret question before the number of allowed unsuccessful logon attempts is exceeded. Automatically unlocking an account after a specified period of time is generally not permitted. However, exceptions may be required based on operational mission or need.

• T1021 Remote Services • T1021.001 Remote Desktop Protocol • T1021.004 SSH • T1078.002 Domain Accounts • T1078.004 Cloud Accounts • T1110 Brute Force • T1110.001 Password Guessing • T1110.002 Password Cracking • T1110.003 Password Spraying • T1110.004 Credential Stuffing • T1133 External Remote Services • T1530 Data from Cloud Storage • T1556 Modify Authentication Process • T1556.001 Domain Controller Authentication • T1556.003 Pluggable Authentication Modules • T1556.004 Network Device Authentication