Lithnet Password Protection for AD
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v1.1
v1.1
  • Home
    • About Lithnet Password Protection
  • Setup
    • Getting started
    • Downloads
    • Setup requirements
    • Installation
    • Creating a new store
    • Load compromised passwords into the store
    • Configure group policy
    • Testing the password filter
  • Auditing
    • Audit existing passwords
  • Help & Support
    • Testing the password filter
    • Troubleshooting steps
    • Frequently asked questions
    • Getting support
    • Change log
  • Advanced Help
    • Powershell reference
      • Add-BannedWord
      • Add-CompromisedPassword
      • Get-PasswordFilterConfig
      • Get-PasswordFilterPolicy
      • Get-PasswordFilterResult
      • Import-BannedWordHashes
      • Import-BannedWords
      • Import-CompromisedPasswordHashes
      • Import-CompromisedPasswords
      • Open-Store
      • Remove-BannedWord
      • Remove-CompromisedPassword
      • Set-PasswordFilterConfig
      • Sync-HashesFromHibp
      • Test-IsADUserPasswordCompromised
      • Test-IsBannedWord
      • Test-IsCompromisedPassword
    • Normalization Rules
    • Event logging and reporting
    • Configuring a length based complexity policy
    • Configuring a points based complexity policy
    • Understanding the store
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  1. Advanced Help

Normalization Rules

The password filter provides the option of using a normalization technique, that when enabled, allow you to prevent the use of common character substitutions and patterns that can lead to easily guessable passwords.

If you take the example P@ssw0rd - a simple variant of the word password with some well-known substitutions. While the symbol, number, and uppercase letter are enough to keep most complexity filters happy, these well-known substitutions provide no additional difficulty to modern password cracking tools. Users will commonly make predictable modifications to dictionary words such as the common Winter2018. Adding winter to the banned store prevents the use of Winter2018, Winter2019 and all other variants into the future.

The normalization process applied to the string is as follows

  1. Lower case the string according to the invariant culture rules

  2. Remove all whitespace from the string

  3. Remove the following leading and trailing symbols and numbers from the string

0123456789!@#$%^&*(){}[];:"'<>,.?\/+_=-~`
  1. Substitute the following characters found in the string

character
substitution

_

.

+

$

s

0

o

4

a

3

e

@

a

^

a

(

c

6

g

1

i

7

t

8

b

2

z

!

i

Examples

The following table highlights some normalization results on common patterns

Input
Normalized output

P@55w0rd!123

password

Winter2017!

winter

Lithnet123!

lithnet

r3qu1r3m3nt5

requirements

PreviousTest-IsCompromisedPasswordNextEvent logging and reporting

Last updated 2 years ago