d-PIT is aware of a class of vulnerabilities related to how some Windows applications may load external dynamic link libraries (DLLs). When an application loads a DLL without specifying a fully qualified path name, Windows will attempt to locate the DLL by searching a defined set of directories. If an application does not securely load DLL files, an attacker may be able to cause the affected application to load an arbitrary library.

By convincing a user to open a file from a location that is under an attacker's control, such as a USB drive or network share, a remote attacker may be able to exploit this vulnerability. Exploitation of this vulnerability may result in the execution of arbitrary code. Additional information regarding this vulnerability can be found in d-PIT Vulnerability Note VU#707943. d-PIT encourages users and administrators to review the vulnerability note and consider implementing the following workarounds until fixes are released by affected vendors

• disable loading libraries from WebDAV and remote network shares
• disable the WebClient service
• block outgoing SMB traffic

Update: Microsoft has released Fix it tool 50522 to assist users in setting the registry key value introduced with Microsoft support article 2264107 to help reduce the risks posed by the DLL loading behavior described in VU#707943. Users and administrators are encouraged to review Microsoft support article 2264107, the Microsoft Security Research & Defense TechNet blog entry, and to consider using the Fix it tool to help reduce the risks. Users should be aware that setting the registry key value as described in the support article or via the Fix it tool may reduce the functionality of some third-party applications.

d-PIT will provide updates when additional details become available.




Relevant URLs:     http://blogs.technet.com/b/srd/archive/2010/08/31/an-update-on-the-dll-preloading-remote-attack-vector.aspx
                          http://support.microsoft.com/kb/2264107