Cracking Windows passwords in 5 seconds (Cool concept, unless you, you know, use Windows)

SecurityFocus BUGTRAQ Mailing List ^ | July 22, 2003 | Philippe Oechslin

[Timesink]

To: BugTraq

Subject: Cracking windows passwords in 5 seconds

Date: Jul 22 2003 8:37PM

Author: Philippe Oechslin

As opposed to unix, windows password hashes can be calculated in advance because no salt or other random information si involved. This makes so called time-memory trade-off attacks possible. This vulnerability is not new but we think that we have the first tool to exploit this.

At LASEC (lasecwww.epfl.ch) we have developed an advanced time-memory trade-off method. It is based on original work which was done in 1980 but has never been applied to windows passwords. It works by calculating all possible hashes in advance and storing some of them in an organized table. The more information you keep in the table, the faster the cracking will be.

We have implemented an online demo of this method which cracks alphanumerical passwords in 5 seconds average (see http://lasecpc13.epfl.ch/ntcrack). With the help of 0.95GB of data we can find the password after an average of 4 million hash operation. A brute force cracker would need to calculate an average of 50% of all hashes, which amounts to about 40 billion hases for alphanumerical passwords (lanman hash).

More info about the method can be found at in a paper at http://lasecwww.epfl.ch/php_code/publications/search.php?ref=Oech03.

Philippe Oechslin

[Pan_Yans Wife]

That's like to old saying that a locked door only keeps honest people from breaking into your home.

[CyberCowboy777]

Any secure 2k Domain is not going to have *real* data on a workstation. Data will be secure within a database with file and network security. Most users will have no access to the data and limited access to network 'sites'.

We happen to run a mixture of Intranet apps and local apps with data connections to servers of one sort or another.

Any data you might get from access to a local PC is expendable.

A windows network does not mean locally stored data with no network security outside user and file level protections.

[Southack]

Precisely.

[CyberCowboy777]

Would I use a 2K/Active Directory/SQL system for a bank?

no.

But I would not use a Unix system for a paper mill.

No one system fits all industry and business and some are inherently more open for purpose and 'other' precautions must be taken.

[Southack]

Indeed.