Feeds

Skype bug may expose users to malicious code

Skype: Does not. Researcher: Does so

SANS - Survey on application security programs

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.

High performance access to file storage

More from The Register

next story
Obama allows NSA to exploit 0-days: report
If the spooks say they need it, they get it
Samsung Galaxy S5 fingerprint scanner hacked in just 4 DAYS
Sammy's newbie cooked slower than iPhone, also costs more to build
Putin tells Snowden: Russia conducts no US-style mass surveillance
Gov't is too broke for that, Russian prez says
Snowden-inspired crypto-email service Lavaboom launches
German service pays tribute to Lavabit
Mounties always get their man: Heartbleed 'hacker', 19, CUFFED
Canadian teen accused of raiding tax computers using OpenSSL bug
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
prev story

Whitepapers

Top three mobile application threats
Learn about three of the top mobile application security threats facing businesses today and recommendations on how to mitigate the risk.
Combat fraud and increase customer satisfaction
Based on their experience using HP ArcSight Enterprise Security Manager for IT security operations, Finansbank moved to HP ArcSight ESM for fraud management.
The benefits of software based PBX
Why you should break free from your proprietary PBX and how to leverage your existing server hardware.
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.
SANS - Survey on application security programs
In this whitepaper learn about the state of application security programs and practices of 488 surveyed respondents, and discover how mature and effective these programs are.