Credentials lost inside single-threaded ASP components (168425)
The information in this article applies to:
- Microsoft Active Server Pages
- Microsoft Internet Information Server 4.0
- Microsoft Internet Information Server 5.0
This article was previously published under Q168425 We strongly recommend that all users upgrade to Microsoft Internet Information Services (IIS) version 6.0 running on Microsoft Windows Server 2003. IIS 6.0 significantly increases Web infrastructure security. For more information about IIS security-related topics, visit the following Microsoft Web site: SYMPTOMS
If a single-threaded Active Server Pages (ASP) component tries to access
resources on a remote machine, access may denied to these resources. One
example of this scenario would be a Visual Basic 4.0 OLE DLL calling the
DIR command on a UNC path. In this scenario, a "Path Not Found" error is
returned.
CAUSE
This problem is caused by a limitation in the way Internet Information
Server (IIS) uses NT threads to manage single-threaded objects. Because of
this limitation, the security credentials are not propagated between
threads. As a result, the single-threaded component is operating in the
security context of the SYSTEM account. When you try to access resources
on other machines, the SYSTEM account is not recognized and access is
denied.
RESOLUTION
There are two common workarounds for this problem:
- Components that have their ThreadingModel registry key set to either
"Apartment" or "Both" do not have this problem. Therefore the best
solution is to create components that use Apartment model threading.
Because Visual Basic 4.0 produces only single-threaded objects, you need
to create your components with another tool such as Visual Basic 5.0 or
Visual C++.
- A final workaround is to add impersonation code to your component so
that it inherits the security credentials of another user that has
access to the desired resources. This approach has some limitations and
is not recommended.
STATUS
This behavior is by design.
REFERENCES
For the latest Knowledge Base articles and other support information on
Visual InterDev and Active Server Pages, see the following page on the
Microsoft Technical Support site:
| Modification Type: | Minor | Last Reviewed: | 6/30/2006 |
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| Keywords: | kberrmsg kbprb kbSecurity kbThread kbWebServer KB168425 |
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