Feeds

Skype: XSS vuln fix is on the way

Backend backdoor to be firmly plugged

Website security in corporate America

Updated Skype has promised to fix a cross-site scripting flaw that exposes Windows users of VoIP technology to potential attack.

The flaw was discovered by independent security researcher Levent Kayan, who warned that a hacker might be able to enter a string of JavaScript code into the "mobile phone" field. This would enable a hacker – provided he or she could trick a victim into adding them as a contact – to compromise the user's Skype account (or "trivially hijack session IDs", as Kayan puts it). Kayan (who has published a video on the bug) adds that the vulnerability also creates a possible mechanism to attack "underlying software and operating systems", a contention strongly disputed by Skype.

Skype said that the bug isn't very serious because it only allows access to the Skype home area, an area of the VoIP client that displays web content. Restrictions on web clients means that the flaw can't be used to inject malware, Skype contends. "The person reporting the bug has only demoed a simple javascript prompt, which is a long leap to loading malware, and the web area is not connected to a Skype account," Skype said.

Despite saying the bug is no big deal Skype promised an update address the vulnerability by the end of the week.

The server-side bug created a possible mechanism for miscreants to redirect Skype users to potentially malicious websites, providing they successfully tricked users into adding them as a contact, as the VoIP outfit explains in an update to its official security blog.

Skype for Windows is not correctly validating some fields of your contacts' profiles. What this means is if one of your Skype contacts has put some specific strings into their profile, it could result in your Skype Home area being redirected to another web page or a message being displayed.

In order for someone to cause these messages to be popped up or to redirect you to a website, they would first have to be one of your accepted Skype contacts. However, this vulnerability should not be there and there is a fix, which we are finalising testing of, that is due to be pushed out early next week.

Cross Site Scripting (XSS) flaws, in general, can be used to present content or pop-ups from potentially hostile websites as if the content had originated from other domains. The class of vulnerability is sometimes used as an adjunct to more highly evolved and subtle phishing scams.

Skype said the necessary fix will be applied without troubling its users with software updates, indicating the bug can be resolved by an update to backend systems alone. ®

Updated to Add

Skype have supplied us with a statement regarding this issue in which the firm says:

The XSS issue relates to the Skype home area of the Skype client. This area provides information on your most frequent contacts and their mood messages. It is correct that the fact that your friends could perform an XSS attack could result in them being able to get a web session token or cookie. But this token is extremely limited in what it can do.

It is totally separate to a Skype logon session, i.e. the account itself. In no way does it allow for hijacking of accounts, resetting of passwords [etc].

The Skype home area is an area of the client that displays web content. As such it has all the protections of standard web clients which prohibit the accessing of local systems or executing arbitrary code.

Protecting users from Firesheep and other Sidejacking attacks with SSL

More from The Register

next story
Hackers pop Brazil newspaper to root home routers
Step One: try default passwords. Step Two: Repeat Step One until success
UK.gov lobs another fistful of change at SME infosec nightmares
Senior Lib Dem in 'trying to be relevant' shocker. It's only taxpayers' money, after all
Spies would need SUPER POWERS to tap undersea cables
Why mess with armoured 10kV cables when land-based, and legal, snoop tools are easier?
TOR users become FBI's No.1 hacking target after legal power grab
Be afeared, me hearties, these scoundrels be spying our signals
'Kim Kardashian snaps naked selfies with a BLACKBERRY'. *Twitterati gasps*
More alleged private, nude celeb pics appear online
Snowden, Dotcom, throw bombs into NZ election campaign
Claim of tapped undersea cable refuted by Kiwi PM as Kim claims extradition plot
Freenode IRC users told to change passwords after securo-breach
Miscreants probably got in, you guys know the drill by now
THREE QUARTERS of Android mobes open to web page spy bug
Metasploit module gobbles KitKat SOP slop
BitTorrent's peer-to-peer chat app Bleep goes live as public alpha
A good day for privacy as invisble.im also reveals its approach to untraceable chats
prev story

Whitepapers

Secure remote control for conventional and virtual desktops
Balancing user privacy and privileged access, in accordance with compliance frameworks and legislation. Evaluating any potential remote control choice.
WIN a very cool portable ZX Spectrum
Win a one-off portable Spectrum built by legendary hardware hacker Ben Heck
Storage capacity and performance optimization at Mizuno USA
Mizuno USA turn to Tegile storage technology to solve both their SAN and backup issues.
High Performance for All
While HPC is not new, it has traditionally been seen as a specialist area – is it now geared up to meet more mainstream requirements?
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.