Microsoft has released two new security updates for Windows XP which may require your immediate attention. They apply to previous OS versions of the Redmond based company as well. You find details below. Unchecked Buffer in File Decompression Functions Could Lead to Code Execution (Q329048) Date: 02 October 2002 Software: Microsoft Windows 98 with Plus! Pack, Windows Me or Windows XP Impact: Two vulnerabilities, the most serious of which could run code of attackers choice Max Risk: Moderate Unchecked Buffer in Windows Help Facility Could Enable Code Execution (Q323255) Date: 02 October 2002 Software: Microsoft Windows 98, 98SE, ME, NT4, 2000 and XP Impact: Attacker could gain control over user's system Max Risk: Critical Read more... Unchecked Buffer in File Decompression Functions Could Lead to Code Execution (Q329048) Issue: Zipped files (files having a .zip extension) provide a means to store information in a way that uses less space on a hard disk. This is accomplished by compressing the files that are put into in the zipped file. On Windows 98 with Plus! Pack, Windows Me and Windows XP, the Compressed Folders feature allows zipped files to be treated as folders. The Compressed Folders feature can be used to create, add files to, and extract files from zipped files. Two vulnerabilities exist in the Compressed Folders function: - An unchecked buffer exists in the programs that handles the decompressing of files from a zipped file. A security vulnerability results because attempts to open a file with a specially malformed filename contained in a zipped file could possibly result in Windows Explorer failing, or in code of the attackers choice being run.
- The decompression function could place a file in a directory that was not the same as, or a child of, the target directory specified by the user as where the decompressed zip files should be placed. This could allow an attacker to put a file in a known location on the users system, such as placing a program in a startup directory. Download now Unchecked Buffer in Windows Help Facility Could Enable Code Execution (Q323255) Issue: The HTML Help facility in Windows includes an ActiveX control that provides much of its functionality. One of the functions exposed via the control contains an unchecked buffer, which could be exploited by a web page hosted on an attacker's site or sent to a user as an HTML mail. An attacker who successfully exploited the vulnerability would be able to run code in the security context of the user, thereby gaining the same privileges as the user on the system. A second vulnerability exists because of flaws associated with the handling of compiled HTML Help (.chm) files that contain shortcuts. Because shortcuts allow HTML Help files to take any desired action on the system, only trusted HTML Help files should be allowed to use them. Two flaws allow this restriction to be bypassed. First, the HTML Help facility incorrectly determines the Security Zone in the case where a web page or HTML mail delivers a .chm file to the Temporary Internet Files folder and subsequently opens it. Instead of handling the .chm file in the correct zone - the one associated with the web page or HTML mail that delivered it - the HTML Help facility incorrectly handles it in the Local Computer Zone, thereby considering it trusted and allowing it to use shortcuts. This error is compounded by the fact that the HTML Help facility doesn't consider what folder the content resides in. Were it to do so, it could recover from the first flaw, as content within the Temporary Internet Folder is clearly not trusted, regardless of the Security Zone it renders in. The attack scenario for this vulnerability would be complex, and involves using an HTML mail to deliver a .chm file that contains a shortcut, then making use of the flaws to open it and allow the shortcut to execute. The shortcut would be able to perform any action the user had privileges to perform on the system. Download now