Feeds

Cracking Windows passwords made easy

Crypto turbo boosto

  • alert
  • submit to reddit

Intelligent flash storage arrays

Cryptographic researchers have outlined techniques to greatly reduce the time it takes to crack alphanumeric Windows passwords.

Brute force attacks on such passwords have always been possible but the techniques outlined in a paper from the Swiss Federal Institute of Technology in Lausanne (EPFL) show how such passwords could be broken up to eight or 10 times more quickly than previously possible.

The technique involves building a large lookup tables that matches the hashed (encoded) versions of passwords stored in Windows with text entered by a user.

By loading such pre-calculated data stored in memory its possible to reduce the time a particular piece of crypto analysis will take. Crypto analysts like Ron Rivest have understood this time-memory trade-off since the 1980s. The Swiss researchers have simply optimised the process, developing a demo programme than can crack Windows passwords more quickly. This demo is available online here.

A paper on this work, Making a Faster Cryptanalytic Time-Memory Trade-Off, is to be presented by Philippe Oechslin and his colleagues at the Swiss Federal Institute of Technology in Lausanne during the Crypto'03 conference next month.

An abstract for the paper explains: "Using 1.4GB of data (two CD-ROMs) we can crack 99.9% of all alphanumerical passwords hashes in 13.6 seconds whereas it takes 101 seconds with the current approach using distinguished points. We show that the gain could be even much higher depending on the parameters used."

By email, Oechslin told us the researchers have since refined the techniques, bringing down the average time it takes to crack passwords to five seconds.

The research re-invigorates calls for Microsoft, in particular, to improve the cryptographic security of its passwords. Although NTHash is more secure than LANManager (the password scheme used in Win 9x) it's still insufficiently random, as the Swiss researchers have shown.

Meanwhile users shouldn't be too concerned about the issue since lifting password hash files in only possible where an attacker has control of your machine. If that happens, weak NT passwords will be the least of your worries. ®

Related Stories

Network worm uses weak Windows passwords
Cracking MS SQL Server passwords
Is SSL safe?
How to get an ATM PIN in 15 guesses
Secure phones no obstacle to wiretapping - US Govt
Citibank gags crypto researchers
109-bit Elliptic Curve Cryptography knocked over with brute force

Fab O'Really T-Shirt at Cash and Carrion
Windows NT User Obliteration

Security for virtualized datacentres

More from The Register

next story
Knock Knock tool makes a joke of Mac AV
Yes, we know Macs 'don't get viruses', but when they do this code'll spot 'em
Shellshock over SMTP attacks mean you can now ignore your email
'But boss, the Internet Storm Centre says it's dangerous for me to reply to you'
Why weasel words might not work for Whisper
CEO suspends editor but privacy questions remain
Feds seek potential 'second Snowden' gov doc leaker – report
Hang on, Ed wasn't here when we compiled THIS document
DEATH by PowerPoint: Microsoft warns of 0-day attack hidden in slides
Might put out patch in update, might chuck it out sooner
China is ALREADY spying on Apple iCloud users, claims watchdog
Attack harvests users' info at iPhone 6 launch
prev story

Whitepapers

Cloud and hybrid-cloud data protection for VMware
Learn how quick and easy it is to configure backups and perform restores for VMware environments.
Getting started with customer-focused identity management
Learn why identity is a fundamental requirement to digital growth, and how without it there is no way to identify and engage customers in a meaningful way.
Reg Reader Research: SaaS based Email and Office Productivity Tools
Read this Reg reader report which provides advice and guidance for SMBs towards the use of SaaS based email and Office productivity tools.
Intelligent flash storage arrays
Tegile Intelligent Storage Arrays with IntelliFlash helps IT boost storage utilization and effciency while delivering unmatched storage savings and performance.
The next step in data security
With recent increased privacy concerns and computers becoming more powerful, the chance of hackers being able to crack smaller-sized RSA keys increases.