This morning The Next Web reported on an exploit where Skype’s password reset web page could be used to hijack a user’s Skype account using only the password associated with the account. So… if you could guess someone’s email address (which can often be found through a Google search), you could effectively take over their Skype account.
Microsoft/Skype has DISABLED this feature while they investigate further so it appears that for the moment the security risk is limited.
However, it may be wise to watch closely the email account associated with your Skype ID for the next bit to see if any random password reset messages are sent to your account. Odds are that attackers will be sniffing around trying to see if there is any other way to exploit the apparent vulnerability.
The Next Web team reports that they were able to reproduce the attack on two Skype accounts of willing victims, confirming that the vulnerability was indeed real. They also reported the issue to Skype and worked with folks there.
The vulnerability is interesting in that it shows the complexity of modern communication applications. Skype is for the most part a desktop/mobile application, but yet it does rely on a centralized cloud-based service for authentication/passwords, etc. A vulnerability in the web interface for that central service then weakens the security of the overall system.
The “good” news for Microsoft/Skype is that because this appears to be a vulnerability in the web interface of the centralized system, this is probably something relatively easy for them to fix – and without requiring any client updates.
Kudos to Microsoft/Skype for reacting quickly to minimize the risk and we look forward to the issue being addressed.
UPDATE #1: Skype has issued a brief statement on their “heartbeat” web site with the same text that has been quoted in several articles.
UPDATE #2: The Verge has an article out now where many people in the comments are suggesting you change the email address associated with your Skype account to something less likely to be guessed. While Microsoft seems to have removed the immediate attack vector and this change is no longer critical to do, it may be something some of you may want to consider.
UPDATE #3: There’s a long Hacker News thread on this issue that also includes a link to an article walking through the exploit step-by-step as well as walking through links to protect your account. Note that because of the steps Microsoft has taken the exploit steps no longer work.