Feeds

Skype bug may expose users to malicious code

Skype: Does not. Researcher: Does so

Security for virtualized datacentres

Updated The latest version of Skype for Windows contains a security vulnerability that allows attackers to inject potentially dangerous code into a user's phone session, a German security researcher has reported.

The XSS, or cross-site scripting, vulnerability in Skype 5.5.0.113 is the result of the voice-over-IP client failing to inspect user-supplied phone numbers for malicious code, researcher Levent Kayan said. As a result, attackers might be able to exploit the bug to inject commands or scripts that hijack the machine running the program.

“An attacker could for example inject HTML/JavaScript code,” Kayan wrote in an advisory published on Wednesday. “It has not been verified though, if it's possible to hijack cookies or to attack the underlying operating system.” An attacker might also exploit the vulnerability to remotely execute malicious JavaScript files on external websites, he said.

Screen shot demonstrating XSS bug in Skype 5.5.0.113

A screen shot from Kayan's website showing the injection bug in action

A Skype spokeswoman disputed Kayan's account.

"We have had this reported to us by various media outlets and have confirmed that the person is mistaken, this is not a web window and while it does cause a phone number to be underlined, does nothing other than this," spokeswoman Brianna Reynaud wrote in an email.

In an email to The Register, Kayan stood his ground, insisting that at a minimum, the flaw allows an attacker to create a hyperlink on a victim's client that leads to a site of the attacker's choosing.

"According to Skype's spokeswoman, I wanted to tell you, that this is not really true what she said, because the entries in (home, office and mobile phone and even in "city") are embedded via HTML," he wrote.

Kayan said the unsafe content is displayed when users view a booby-trapped profile. The malicious profile is created by inserting a JavaScript command or web address where a phone number is expected. The reported vulnerability is eerily reminiscent of an XSS bug Kayan reported in an earlier version of Skype last month.

Such vulnerabilities open the possibility of creating self-replicating attacks if they can be used to target users contained in each victim's contact list. As each new user is exploited, the worm spreads virally by attacking a whole new set of people. A vulnerability reported in May for Mac versions of Skype was described as wormable, though there are no reports it was ever exploited in the wild. It's unclear if the current vulnerability might also allow for self-replicating attacks.

Microsoft is in the process of acquiring the popular internet-based phone service. ®

This article was updated to add comment from Skype spokeswoman and a response from Kayan.

Secure remote control for conventional and virtual desktops

More from The Register

next story
Russian hackers exploit 'Sandworm' bug 'to spy on NATO, EU PCs'
Fix imminent from Microsoft for Vista, Server 2008, other stuff
Microsoft pulls another dodgy patch
Redmond makes a hash of hashing add-on
FYI: OS X Yosemite's Spotlight tells Apple EVERYTHING you're looking for
It's on by default – didn't you read the small print?
'LulzSec leader Aush0k' found to be naughty boy not worthy of jail
15 months home detention leaves egg on feds' faces as they grab for more power
Forget passwords, let's use SELFIES, says Obama's cyber tsar
Michael Daniel wants to kill passwords dead
FBI boss: We don't want a backdoor, we want the front door to phones
Claims it's what the Founding Fathers would have wanted – catching killers and pedos
Kill off SSL 3.0 NOW: HTTPS savaged by vicious POODLE
Pull it out ASAP, it is SWISS CHEESE
prev story

Whitepapers

Forging a new future with identity relationship management
Learn about ForgeRock's next generation IRM platform and how it is designed to empower CEOS's and enterprises to engage with consumers.
Why cloud backup?
Combining the latest advancements in disk-based backup with secure, integrated, cloud technologies offer organizations fast and assured recovery of their critical enterprise data.
Win a year’s supply of chocolate
There is no techie angle to this competition so we're not going to pretend there is, but everyone loves chocolate so who cares.
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?
Intelligent flash storage arrays
Tegile Intelligent Storage Arrays with IntelliFlash helps IT boost storage utilization and effciency while delivering unmatched storage savings and performance.