A new flaw has been found that will slow down and crash Windows 8.1, Windows 7 and Vista (Vista is out of support) systems. Attackers could use this flaw to attack other users’ computers by using one of the special filenames as an image source; the browser would try to access the bad file, and Windows would promptly fall over.
The flaw allows a malicious user to use a website and try to load an image file with the “$MFT” name in the directory path. Microsoft Windows uses “$MFT” for particular metadata files that are used by NTFS file system, and Windows 7 and Windows 8 crash to handle this directory name correctly.
The “$MFT” file exists in the main directory of each NTFS volume, but the NTFS driver handles it in particular ways, and it’s hidden and inaccessible for viewing to most software. Tries to open the file are usually blocked, but in a move evocative of the Windows 9x flaw, if the filename is used as if it were a directory name, for example, attempting to open the file “c:\$MFT\123” then the NTFS driver takes out a lock on the file and never releases it. This blocks any and all other tries to reach the file system, every program will begin to hang, making the machine also hang and unusable until it is rebooted.
The flaw has been reported to Microsoft, but until now it has not told when the problem will be patched.