- Login to a different admin account.
- Delete your account, choosing "Don't change the home folder" option.
- Open Terminal and rename your home folder, eliminating the " (Deleted)" part -- sudo mv "/Users/yourshortname (Deleted)" /Users/yourshortname
- Unbind your machine (Login Options tab, at the bottom)
- Create a new account with the same short name.
- Use the existing folder, when you're prompted.
An update to my comment of Sep 6 at 15:24 and part of #4 -- Apple has just issued a supplemental update that fixes this loophole. The text of their security announcement is:
APPLE-SA-2013-10-03-1 OS X v10.8.5 Supplemental Update
OS X v10.8.5 Supplemental Update is now available and addresses the
Directory Services Available for: OS X Mountain Lion v10.8 to v10.8.5
Impact: A local user may modify Directory Services records with
Description: A logic issue existed in Directory
Services's verification of authentication credentials allowing a local
attacker to bypass password validation. The issue was addressed
through improved credential validation. CVE-ID CVE-2013-5163 : the
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