Feeds

Skype bug may expose users to malicious code

Skype: Does not. Researcher: Does so

Choosing a cloud hosting partner with confidence

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.

Internet Security Threat Report 2014

More from The Register

next story
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?
Russian hackers exploit 'Sandworm' bug 'to spy on NATO, EU PCs'
Fix imminent from Microsoft for Vista, Server 2008, other stuff
Edward who? GCHQ boss dodges Snowden topic during last speech
UK spies would rather 'walk' than do 'mass surveillance'
Microsoft pulls another dodgy patch
Redmond makes a hash of hashing add-on
NOT OK GOOGLE: Android images can conceal code
It's been fixed, but hordes won't have applied the upgrade
Apple grapple: Congress kills FBI's Cupertino crypto kybosh plan
Encryption would lead us all into a 'dark place', claim G-Men
'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
China is ALREADY spying on Apple iCloud users, claims watchdog
Attack harvests users' info at iPhone 6 launch
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 and how to choose the right cloud vendor
The benefits of cloud-based storage in your processes. Eliminate onsite, disk-based backup and archiving in favor of cloud-based data protection.
Three 1TB solid state scorchers up for grabs
Big SSDs can be expensive but think big and think free because you could be the lucky winner of one of three 1TB Samsung SSD 840 EVO drives that we’re giving away worth over £300 apiece.
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.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.