Feeds

Marlinspike demos MS-CHAPv2 crack

‘The strength of a single DES encryption’ not enough

SANS - Survey on application security programs

Security researcher Moxie Marlinspike has turned his attention to VPNs based on Microsoft’s MS-CHAPv2 protocol, demonstrating software at Defcon that can capture and crack passwords.

Chapcrack parses the credential information out of MS-CHAPv2 handshakes, which are then sent to Cloudcracker. Cloudcracker will then return a packet that can be decrypted by Chapcrack to recover the password.

As noted by ThreatPost, MS-CHAPv2 is an old protocol that should have been replaced, but hasn’t: criticisms go back as far as 1999.

Marlinspike writes in this blog post, “It shows up most notably in PPTP VPNs, and is also used quite heavily in WPA2 Enterprise environments”.

There is, he writes, “only one unknown in the entire protocol – the MD4 hash of the user’s passphrase, which is used to construct three separate DES keys”. Since the MD4 hash of a user’s password “is enough to authenticate as them”, Marlinspike and collaborator David Hulton of Pico computing made this the focus of Chapcrack.

While El Reg doesn’t propose reproducing Marlinspike’s technical explanation in full, it’s worth a read, if only for the reasoning behind how the attack works: from what looks like a seriously difficult computational task, he and Hulton winnow the problem down to a complexity of 256: “the security of MS-CHAPv2 can be reduced to the strength of a single DES encryption” [original emphasis].

Pico Computing’s key contribution to the effort is in the form of an FPGA-based box that can “crack any MS-CHAPv2 handshake in less than a day”, Marlinspike writes.

Marlinspike says that MS-CHAPv2 should be purged from the Internet, advising that PPTP traffic “should be considered unencrypted”, and that MS-CHAPv2 enterprise users should begin migrating – now. ®

Combat fraud and increase customer satisfaction

More from The Register

next story
Parent gabfest Mumsnet hit by SSL bug: My heart bleeds, grins hacker
Natter-board tells middle-class Britain to purée its passwords
Obama allows NSA to exploit 0-days: report
If the spooks say they need it, they get it
Web data BLEEDOUT: Users to feel the pain as Heartbleed bug revealed
Vendors and ISPs have work to do updating firmware - if it's possible to fix this
Samsung Galaxy S5 fingerprint scanner hacked in just 4 DAYS
Sammy's newbie cooked slower than iPhone, also costs more to build
Mounties always get their man: Heartbleed 'hacker', 19, CUFFED
Canadian teen accused of raiding tax computers using OpenSSL bug
Snowden-inspired crypto-email service Lavaboom launches
German service pays tribute to Lavabit
One year on: diplomatic fail as Chinese APT gangs get back to work
Mandiant says past 12 months shows Beijing won't call off its hackers
prev story

Whitepapers

Designing a defence for mobile apps
In this whitepaper learn the various considerations for defending mobile applications; from the mobile application architecture itself to the myriad testing technologies needed to properly assess mobile applications risk.
3 Big data security analytics techniques
Applying these Big Data security analytics techniques can help you make your business safer by detecting attacks early, before significant damage is done.
Five 3D headsets to be won!
We were so impressed by the Durovis Dive headset we’ve asked the company to give some away to Reg readers.
The benefits of software based PBX
Why you should break free from your proprietary PBX and how to leverage your existing server hardware.
Securing web applications made simple and scalable
In this whitepaper learn how automated security testing can provide a simple and scalable way to protect your web applications.