Microsoft Windows 2000/XP/2003/Vista ReadDirectoryChangesW informaton leak

2007-02-22T00:00:00
ID SECURITYVULNS:DOC:16139
Type securityvulns
Reporter Securityvulns
Modified 2007-02-22T00:00:00

Description

Title: Microsoft Windows 2000/XP/2003/Vista ReadDirectoryChangesW informaton leak Author: 3APA3A, http://securityvulns.com Affected: Microsoft Windows 2000,XP,2003,Vista Exploitable: Yes Type: Remote (from local network), authentication required (NULL session was not tested). Class: Information leak CVE: CVE-2007-0843

Intro:

It's very simple yet interesting vulnerability. ReadDirectoryChangesW() API allows application to monitor directory changes in real time. bWatchSubtree parameter of this functions allows to monitor changes within whole directory tree with a root in monitored directory. To monitor changes directory must be open with LIST access. Function returns the list of modified files with a type of modification. File modification refers to any modification of file record in directory.

Vulnerability:

ReadDirectoryChangesW() doesn't check user's permissions for child directories.

Impact:

Any unprivileged user with LIST access to parent directory can monitor any files in child directories regardless of files permissions. Because by default Windows updates access time of any accessed files on NTFS volumes, it makes it possible for user to gather information about NTFS-protected files, their names and time of access to the files (reading, writing, creation, deletion, renaming, etc). Filenames may contain sensitive information or leak information about user's behavior (e.g. cookies files).

Exploit:

http://securityvulns.com/files/spydir.c

Usage example:

spydir \\corpsrv\corpdata

I believe you find this utility useful regardless of this security issue. It shows names of accessed/modified files for given directory in real time (it seems there are non-security bugs in ReadDirectoryChangesW implementations, e.g. you can not see non-ASCII names and some changes are missing).

Compiled version can be downloaded from http://securityvulns.com/soft/

Workaround:

Avoid creation of more secure folder in less secure ones. Avoid using sensitive data in documents naming.

Vendor (Microsoft):

January, 17 2006 Initial vendor notification January, 18 2006 Vendor reply (assigned) January, 26 2006 2nd vendor notification February, 7 2006 3rd vendor notification February, 9 2006 Vendor accepted vulnerability as "service pack class" for Windows XP and Windows 2003. February, 9 2006 Accepted to wait until SP February, 22 2006 Vendor gives SP timelines (late 2006 for W2K3 SP2 and 2007 for XP SP3) February, 22 2007 Public release, because Windows Vista is released with same vulnerability.