Converting msDS-UserPasswordExpiryTimeComputed to DateTime

The msDS-UserPasswordExpiryTimeComputed attribute in Active Directory stores the user’s password expiration time as a large integer in Windows FileTime format. This format counts 100-nanosecond intervals from January 1, 1601 (UTC). To get a readable date and time, you must convert this number to a standard datetime format using the appropriate method for your platform.

How to Convert:

• Use built-in functions like FromFileTimeUtc in PowerShell or .NET.
• In Python, add the FileTime interval (converted to microseconds) to the epoch starting at 1601-01-01.

Example in PowerShell:

[DateTime]::FromFileTimeUtc($filetimeValue)

Handling the Special “Magic” Number:
If the value equals 9223372036854775807 (the maximum 64-bit integer), it is a special indicator that the password never expires. This number is not a real timestamp and should not be converted to a date. Instead, treat it as a flag meaning “no expiration.”

Summary:

• Convert valid FileTime values to datetime for expiry information.
• Recognize 9223372036854775807 as a sentinel meaning “password never expires.” Avoid converting this sentinel to a datetime.