Unsuccessful Logon Attempts
✓ LOW ✓ MODERATE ✓ HIGHRequirements NIST SOURCE
Requirement Context
This element is part of AC-7 — Unsuccessful Logon Attempts. See the Assessment section below for the related SP 800-53A examine/interview/test procedures. No engineering interpretation has been authored for this control yet.
Requirement Context
This element is part of AC-7 — Unsuccessful Logon Attempts. See the Assessment section below for the related SP 800-53A examine/interview/test procedures. No engineering interpretation has been authored for this control yet.
Discussion (NIST Supplemental Guidance)
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.
Enhancements NIST SOURCE
AC-7(1) Automatic Account Lock WITHDRAWN
Withdrawn. Incorporated into AC-7.
AC-7(2) Purge or Wipe Mobile Device LOW MODERATE HIGH
Purge or wipe information from [mobile devices] based on [purging or wiping requirements and techniques] after [number] consecutive, unsuccessful device logon attempts.
Discussion
A mobile device is a computing device that has a small form factor such that it can be carried by a single individual; is designed to operate without a physical connection; possesses local, non-removable or removable data storage; and includes a self-contained power source. Purging or wiping the device applies only to mobile devices for which the organization-defined number of unsuccessful logons occurs. The logon is to the mobile device, not to any one account on the device. Successful logons to accounts on mobile devices reset the unsuccessful logon count to zero. Purging or wiping may be unnecessary if the information on the device is protected with sufficiently strong encryption mechanisms.
AC-7(3) Biometric Attempt Limiting LOW MODERATE HIGH
Limit the number of unsuccessful biometric logon attempts to [number].
Discussion
Biometrics are probabilistic in nature. The ability to successfully authenticate can be impacted by many factors, including matching performance and presentation attack detection mechanisms. Organizations select the appropriate number of attempts for users based on organizationally-defined factors.
AC-7(4) Use of Alternate Authentication Factor LOW MODERATE HIGH
- (a) Allow the use of [authentication factors] that are different from the primary authentication factors after the number of organization-defined consecutive invalid logon attempts have been exceeded; and
- (b) Enforce a limit of [number] consecutive invalid logon attempts through use of the alternative factors by a user during a [time period].
Discussion
The use of alternate authentication factors supports the objective of availability and allows a user who has inadvertently been locked out to use additional authentication factors to bypass the lockout.
Implementation Guidance
Original engineering commentary written for this explorer — not NIST source text and not authoritative guidance.
No engineering interpretation has been authored for AC-7 yet. This section is architected to receive it — see the Requirements and Assessment sections above for the authoritative NIST source content in the meantime.
Assessment
Assessment Objectives
- the number of consecutive invalid logon attempts by a user allowed during a time period is defined;
- the time period to which the number of consecutive invalid logon attempts by a user is limited is defined;
- one or more of the following PARAMETER VALUES is/are selected: {lock the account or node for <AC-07_ODP[04] time period>; lock the account or node until released by an administrator; delay next logon prompt per <AC-07_ODP[05] delay algorithm>; notify system administrator; take other <AC-07_ODP[06] action>};
- time period for an account or node to be locked is defined (if selected);
- delay algorithm for the next logon prompt is defined (if selected);
- other action to be taken when the maximum number of unsuccessful attempts is exceeded is defined (if selected);
- a limit of <AC-07_ODP[01] number> consecutive invalid logon attempts by a user during <AC-07_ODP[02] time period> is enforced;
- automatically <AC-07_ODP[03] SELECTED PARAMETER VALUES> when the maximum number of unsuccessful attempts is exceeded.
Examine
[SELECT FROM: Access control policy; procedures addressing unsuccessful logon attempts; system design documentation; system configuration settings and associated documentation; system audit records; system security plan; other relevant documents or records].
Interview
[SELECT FROM: Organizational personnel with information security responsibilities; system developers; system/network administrators].
Test
[SELECT FROM: Mechanisms implementing access control policy for unsuccessful logon attempts].
Overlays
STIGs & CCIs
No STIG checks or CCI mappings are currently loaded for AC-7. This section is architected to display, per product: STIG ID, Finding ID, Severity, Title, Description, Check, Fix, CCI, and NIST control mapping — but nothing is populated here until a real DISA STIG/CCI dataset is ingested.
Learn more about STIG/CCI integration →Evidence
Categorized from the SP 800-53A "Examine"/"Test" artifact list above by keyword — not an authoritative NIST evidence list.
Policy
- Access control policy
- system security plan
Configuration
- system design documentation
- system configuration settings and associated documentation
Testing
- Mechanisms implementing access control policy for unsuccessful logon attempts
Other Records
- procedures addressing unsuccessful logon attempts
- system audit records
- other relevant documents or records