Feeds

Cisco and Juniper 'clientless' VPNs expose netizens

No cure for authentication bypass

SANS - Survey on application security programs

Virtual private networking software from Cisco Systems, Juniper, and other manufacturers can make users susceptible to a variety of web-based attacks, the US Computer Emergency Readiness Team warned on Monday.

So-called clientless SSL VPN products, which provide browser-based access to intranets, email and other internal resources, expose users to attacks that allow eavesdroppers to view passwords and keystrokes. Of the 90 companies known to market products that use the technology, Cisco, Juniper, SafeNet and Sonic Wall are known to be affected, while it's unclear if an additional 77 are vulnerable.

The weakness can be exploited only in attacks that are narrowly targeted at a particular website or domain, so there's not much chance of attack code going public that automates the process. But given the wealth of proprietary information hiding behind the typical VPN, it can nonetheless be used by determined attackers to bypass a website's authentication.

"It does look like a legitimate concern," said independent hacker Chris Paget. "I would be quite concerned if my site was working in the way described in the advisory. It's definitely a vulnerability and definitely something people should be aware of."

Clientless SSL subverts what's known as the same origin policy. That's the fundamental tenet of web security that forbids javascript, cookies and other content on one domain name from being available to a separate internet address.

Clientless SSL VPNs allow users to tunnel through a website that's protected by secure sockets layer encryption when accessing webmail, intranets and other sites. In the process, third-party hyperlinks and cookies are converted so they can be used by the VPN. Attackers can cause the content to be altered in a way that allows session IDs used to authenticate users to be stolen or modified.

"By convincing a user to view a specially crafted web page, a remote attacker may be able to obtain VPN session tokens and read or modify content (including cookies, script, or HTML content) from any site accessed through the clientless SSL VPN," the CERT advisory stated. "This effectively eliminates same origin policy restrictions in all browsers."

The technique can be used to subvert domain-based content restrictions in Internet Explorer security zones and the NoScript addon for Firefox.

There is no solution to the weakness, the advisory warns. "Depending on their specific configuration and location in the network, these devices may be impossible to operate securely." Given the severity of the advisory, it would behoove clientless SSL VPN users to check with their supplier to find out if their particular implementation is vulnerable.

The issue was discovered by researchers David Warren and Ryan Giobbi, with help from Michael Zalewski. The advisory is here. ®

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
Samsung Galaxy S5 fingerprint scanner hacked in just 4 DAYS
Sammy's newbie cooked slower than iPhone, also costs more to build
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
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
Call of Duty 'fragged using OpenSSL's Heartbleed exploit'
So it begins ... or maybe not, says one analyst
NSA denies it knew about and USED Heartbleed encryption flaw for TWO YEARS
Agency forgets it exists to protect communications, not just spy on them
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.