Windows passwords broken in seconds

NEWS

Swiss researchers released a paper on Tuesday outlining a way to speed the cracking of alphanumeric Windows passwords, reducing the time to break such codes to an average of 13.6 seconds from 1 minute 41 seconds. The method involves using large lookup tables to match encoded passwords to the original text entered by a user, thus speeding the calculations required to break the codes. Called a time-memory trade-off, the situation means that an attacker with an abundance of computer memory can reduce the time it takes to break a secret code. The results highlight a fact about which many security researchers have worried: Microsoft's manner for encoding passwords has certain weaknesses that make such techniques particularly effective, Philippe Oechslin, a senior research assistant and lecturer at the Cryptography and Security Laboratory of the Swiss Federal Institute of Technology in Lausanne (EPFL), wrote in an email to CNET News.com. "Windows passwords are not very good," he wrote. "The problem with Windows passwords is that they do not include any random information." Oechslin outlined a way to take advantage of that lack of randomness on Tuesday when he published a paper and a Web demonstration of the technique. The research builds on previous work showing that encryption algorithms can be sped up with the help of large lookup tables. Increasing the size of the lookup tables reduces the amount of time, on average, that it takes to search for a password. The researcher used a 1.4GB lookup table and a single computer with an AMD 2500+ processor and 1.5GB RAM to offer people a way to test the process online. Oechslin said he hadn't notified Microsoft of the issue before publishing his paper. He said his research has been more about creating efficient time-memory trade-offs, not about breaking Microsoft passwords. "This is not a new vulnerability," he said. "It is only the first time that it has been worked in so much detail. Microsoft passwords are just a nice example to demonstrate the theoretical results." Microsoft has used two encoding schemes, also known as hashing functions, to encrypt passwords. The first, known as LANManager or LANMan, was used by Windows 3.1, 95, 98, Me and early NT systems to secure passwords that were used to connect to early Windows networks. The LANMan scheme has several weaknesses, including converting all characters to uppercase, splitting passwords into 7-byte chunks, and not using an additional random element known as "salt." While the more recent NTHash fixes the first two weaknesses, it still does not use a random number to make the hashes more unique. The result: the same password encoded on two Windows machines will always be the same. That means that a password cracker can create a large lookup table and break passwords on any Windows computer. Unix, Linux and the Mac OS X, however, add a 12-bit salt to the calculation, making any brute force attempt to break the encryption take 4,096 times longer or require 4,096 times more memory. While an attacker would need administrator rights to a system to grab the file that contains the password hashes, the file is still valuable, said David Dittrich, a senior security researcher at University of Washington. "The object is to use rights you have gained on one resource to break into other systems," he said. "If you have broken into a server and you have a hash, you can escalate your privilege and slowly move your way through the network. If you can get your hands on the hash, then 'game over.'" Users can protect themselves against the attack by adding non-alphanumeric characters to a password. Including other symbols besides alphanumeric characters adds complexity to the process of breaking passwords and that means the cracker needs more time or more memory or both. Oechslin, for example, has created a new version of his program using 20GB of lookup tables that can break passwords made of numbers, letters and 16 other characters in an average of 30 seconds for large batches of passwords. "To make things more complex, we could have generated a set of data half as big (10GB), which would (have broken) the same passwords faster, but we would have spent multiple times the amount of work calculating this data," he wrote. "So there is another trade-off, namely between precalculation time and memory or cracking time."

For all security-related news, including updates on the latest viruses, hacking exploits and patches, check out ZDNet UK's Security News Section. Let the editors know what you think in the Mailroom.

Talkback

how can I buy this crack password CD?

via Facebook 30 June, 2005 23:46

I forget my computer lock password. So, I need broken password software.

Min Thu Wai 11 August, 2010 10:52

Post your comment

In order to post a comment you need to be registered and logged in.

You can also log in with Facebook. Log in or create your ZDNet UK account below

By signing up for this service, you indicate that you agree to our Terms and Conditions and have read and understood our Privacy Policy. Questions about membership? Find the answers in the Community FAQ

ZDNet UK Live

Make that 13 people now - I got refused today at Manchester airport. I thought I was up to date on this legislation - I knew of the EU ruling from...

25 minutes ago by bootlegger on UK airport body scans will not be opt out

Don't forget to check out apps like GoodReader or SlideShark either, they're indispensible for people on the go in presentation situations. Best...

3 hours ago by tinycg on Four top iPad apps for people on the move

Well it seems there is something a number of us agree on. Why is the Ubuntu Unity launcher so ugly? I thought perhaps it was something to do with...

8 hours ago by TerryRK on A tale of two distros: Ubuntu and Linux Mint

Duplicate comments are not made intentionally. Its very good to know that now you are keeping check on this problem because sometimes a commenter...

17 hours ago by Freebies202 on Microsoft fixes blog comments, speeds up blogs with open source

"the very significant number of users" and "many (most) of us" - you have no evidence for these statements. It is a fact that most users are saying...

1 day ago by kevinmchapman on A tale of two distros: Ubuntu and Linux Mint

Another grammar faux pas is the improper use of "you". When sitting down down in a restaurant, for example, I get cringe when the waitress...

1 day ago by Marg Menzies Harrison via Facebook on 10 flagrant grammar mistakes that make you look stupid

And NOW, folks, for Canonical's next trick... Kubuntu is late. Here's a pencil. Draw your own conclusions. cf.:...

1 day ago by zdnetukuser on Linux Minterface

@kevinmchapman. The discussion here reflects the very significant number of users who really do like the traditional menu system and who wish to...

1 day ago by Moley on A tale of two distros: Ubuntu and Linux Mint

Er, no... It is an efficient means of finding the application/file/setting you need in one place. The icons are a simply a fallback for when you...

1 day ago by kevinmchapman on A tale of two distros: Ubuntu and Linux Mint

Isn't the provision of a text based search an admission by the developers that the mass of icons approach does not work? I don't need to use a...

1 day ago by TerryRK on A tale of two distros: Ubuntu and Linux Mint

"Unity and GNOME 3 both abandon the old text-based cascading menus in favour of a graphical icon-driven system." Point truly missed. Both use a...

1 day ago by kevinmchapman on A tale of two distros: Ubuntu and Linux Mint

whs001 - Thank you, I'm glad you liked the article. I absolutely agree with you on your first point. I should perhaps have made it clearer that...

1 day ago by TerryRK on A tale of two distros: Ubuntu and Linux Mint

If we allow corporate interest to dictate the way our government circumvents due process against foreign entities then we should accept the same...

1 day ago by via Facebook on ACTA stumbles in Germany

I totally dislike pirating of works, I fear that artists will be deterred from creating works if they think that they are going to get ripped off....

1 day ago by GHar123 on ACTA stumbles in Germany

How dare film makers, artists or anybody that invests in creativity stop us pirating their works for free. I want to be able to walk into my local...

2 days ago by JCB33 on ACTA stumbles in Germany

@GrueMaster. I prefer horses for courses rather than one size fits all. I, and I suspect most other computer users, do not really wish to have...

2 days ago by Moley on A tale of two distros: Ubuntu and Linux Mint

The product that scares me every time I have to use it is the Office 2007 version of Excel. The first bug that I found was applying the median...

2 days ago by greycynic on Ten flawed products that derail productivity

Nice review and very informative. One thing I'd like to add (in reply to whs001's 1st question), the main reason to have the same interface from...

2 days ago by GrueMaster on A tale of two distros: Ubuntu and Linux Mint

I'be been using Mint 12 since the RC came out, and I am far more happy with the Cinnamon, the Mate, and, yes (with extensions), theGnome 3...

2 days ago by Frederick Wrigley via Facebook on A tale of two distros: Ubuntu and Linux Mint

Excellent article. One small correction, though--although a fresh installation of Linux Mint 12 will, indeed, provide the user with a version of...

2 days ago by bdantas on A tale of two distros: Ubuntu and Linux Mint

Featured white papers

Latest jobs

Windows passwords broken in seconds

Daily Newsletters

Topics

Related stories

IT users in password hell

RSA: Split passwords make secrets safer

Worms target lazy passwords

Heart of England NHS begins massive digitisation plan

Hard-drive woes hit PC shipments in fourth quarter

Talkback

Post your comment

ZDNet UK Live

Latest in IT Strategy

Heart of England NHS begins massive digitisation plan

Hard-drive woes hit PC shipments in fourth quarter

Featured white papers

Latest jobs

PHP Web Developer - html, css, javascript

Java Developer, Online Gaming, London

Quant Dev, Hedge Fund, FX, Excel VBA

Inside ZDNet UK

A tale of two distros: Ubuntu and Linux Mint

2012 Predictions: VCE FastPath, VI SAN Probe & Hadoop

BlackBerry Bold 9790

Make faster, smarter decisions using BI

Ten factors that make Ubuntu 11.10 a hit

Toshiba Portégé Z830-10P Review

BT's archive: Pictures from the vault

News & Analysis

Reviews

Blogs

Resources

About Us

Member Services

Special Features

Advertising Features

ZDNet UK / News and Analysis / Business of IT / IT Strategy

Windows passwords broken in seconds

Daily Newsletters

Topics

Related stories

Talkback

Post your comment

Get ZDNet UK's daily newsletter

Enter your email address to sign up

ZDNet UK Live

Latest in IT Strategy

Featured white papers

Latest jobs

Inside ZDNet UK

Resources

About Us

Member Services

Special Features

Advertising Features