Finding Disabled Accounts In Active Directory

When using Active Directory (AD) as a source of user data, it’s useful to filter out disabled accounts. Unfortunately, AD has a lot of different security-related settings glomed together in the userAccountControl attribute. Which means there’s no single attribute/value combination you can use to ignore disabled accounts.

The decimal value you see for userAccountControl isn’t terribly useful, but display it in binary and each bit position has a meaning. The userAccountControl value is just the number with a bunch of bits set. Numbering the bits from left to right, here is what each one means.

Bit # Meaning
0 Unused – must be 0
1 Unused – must be 0
2 Unused – must be 0
3 Unused – must be 0
4 Unused – must be 0
5 ADS_UF_PARTIAL_SECRETS_ACCOUNT
6 ADS_UF_NO_AUTH_DATA_REQUIRED
7 ADS_UF_TRUSTED_TO_AUTHENTICATE_FOR_DELEGATION
8 ADS_UF_PASSWORD_EXPIRED
9 ADS_UF_DONT_REQUIRE_PREAUTH
10 ADS_UF_USE_DES_KEY_ONLY
11 ADS_UF_NOT_DELEGATED
12 ADS_UF_TRUSTED_FOR_DELEGATION
13 ADS_UF_SMARTCARD_REQUIRED
14 Unused – must be 0
15 ADS_UF_DONT_EXPIRE_PASSWD
16 Unused – must be 0
17 Unused – must be 0
18 ADS_UF_SERVER_TRUST_ACCOUNT
19 ADS_UF_WORKSTATION_TRUST_ACCOUNT
20 ADS_UF_INTERDOMAIN_TRUST_ACCOUNT
21 Unused – must be 0
22 ADS_UF_NORMAL_ACCOUNT
23 Unused – must be 0
24 ADS_UF_ENCRYPTED_TEXT_PASSWORD_ALLOWED
25 ADS_UF_PASSWD_CANT_CHANGE
26 ADS_UF_PASSWD_NOTREQD
27 ADS_UF_LOCKOUT
28 ADS_UF_HOMEDIR_REQUIRED
29 Unused – must be 0
30 ADS_UF_ACCOUNT_DISABLE
31 Unused – must be 0

Bit #30 indicates if the account is disabled — 1 if the account is disabled, 0 if the account is enabled. Simple and direct approach is to “and” the attribute value with 0b10 to extract just the bit we care about. When the and operation returns 0, the account is enabled. When it returns 2 (0x10), the account is disabled.

 

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