Windows Bug Leaks Microsoft Account Login Data

An issue affecting Microsoft’s Windows operating system could result in leaked user credentials if Internet Explorer and Edge are being used, researchers discovered.

The bug is by no means new, as it was initially reported almost two decades ago, when Aaron Spangler found it in WinNT/Win95. After the initial report in 1997, researchers discussed the bug at last year’s annual Black Hat security conference. However, neither researchers nor Microsoft thought of it as a great issue until now.

What changed in the meantime is the fact that researchers discovered that the bug can leak Microsoft account credentials, including passwords. ValdikSS from the Russian provider ProstoVPN reveals that, because Windows 8 and later allow users to login with Microsoft accounts, the issue becomes a great security concern.

The vulnerability was shown to have wider implications, as it could compromise all of the services a user has connected to their Microsoft account, such as OneDrive, Outlook, Skype, Xbox Live, Office 365, MSN, Windows Mobile, and Bing.

An attacker can exploit the issue by setting up a network share and tricking the user to visit any IP address of that share. The flaw can be exploited by embedding an image into a website if the victim uses Internet Explorer or Edge, or by sending the network share into an email, if the victim uses Microsoft Outlook.

If successful, the attack leaks user’s login name and the NTML hash of the password and Windows domain. If the password is weak, however, the hash can be cracked in a matter of seconds.

To stay protected, users should employ strong passwords that are difficult to crack, and should also consider resetting the password if they suspect a compromise.

Moreover, users are advised to stop using Microsoft software capable of accessing network shares over the Internet, including Internet Explorer, Edge or Outlook. Not using a Microsoft login on a local Windows machine also prevents this attack from being successful.

Related: Researcher Gets $13,000 for Microsoft Authentication Flaw

Related: Windows Information Protection to Address Data Leaks in Windows 10