Skype Aware Of XSS Vulnerability In iOS Apps, “Working Hard To Fix” It

If you’re using Skype for iOS on your iPhone or iPod touch, consider yourself warned: a cross-site scripting vulnerability looms in the “Chat Message” window in version 3.0.1 and earlier versions.

The hole allows attackers to execute malicious JavaScript code that runs when a victim views a chat message, enabling theft of information, including a user’s address book (see video below).

Skype says it is aware of the security issue, and had issued the following statement:

“We are working hard to fix this reported issue in our next planned release which we hope to roll out imminently. In the meantime we always recommend people exercise caution in only accepting friend requests from people they know and practice common sense internet security as always.”

The non-patronizing first sentence would have been sufficient, Skype.

AppSec Consulting security researcher Phil Purviance, who also made the video below, writes:

Executing arbitrary Javascript code is one thing, but I found that Skype also improperly defines the URI scheme used by the built-in webkit browser for Skype. Usually you will see the scheme set to something like, “about:blank” or “skype-randomtoken”, but in this case it is actually set to “file://”. This gives an attacker access to the users file system, and an attacker can access any file that the application itself would be able to access.

File system access is partially mitigated by the iOS Application sandbox that Apple has implemented, preventing an attacker from accessing certain sensitive files. However, every iOS application has access to the users AddressBook, and Skype is no exception.

On Twitter, Purviance says he reported the XSS vulnerability to Skype nearly a month ago.

Let’s hope a fix follows shortly now that he’s gotten media attention.