Certain DOS reserved filenames may cause ColdFusion to display the physical web root
directory when ColdFusion is used with Microsoft IIS.
Originally Posted: May 9, 2002
Last Updated: May 9, 2002
Summary
Certain DOS reserved filenames, such as NUL or PRN, can cause ColdFusion to display the path to the
web root directory in an error message.
For example:
Error Diagnostic Information
Cannot open CFML file
The requested file "c:\inetpub\wwwroot\NUL.cfm" cannot be found.
When two or more periods are used in the filename, a different message is displayed:
Error Diagnostic Information
The template specification, 'c:\InetPub\wwwroot\NUL..cfm', is illegal.
Information about the web root location does not by itself grant unauthorized access.
This information could potentially be useful in conjunction with some other vulnerability,
especially if the web root has been changed from the default location: c:\Inetpub\wwwroot.
Issue
Two solutions are available to prevent IIS from passing DOS reserved filenames to ColdFusion for processing.
- Install and configure the Microsoft URLScan Security Tool
- Change IIS properties to check that files exist
Method 1 - The Microsoft URLScan utility
The URLScan IIS Security Tool and instructions is available
at
http://www.microsoft.com/technet/security/tools/URLscan.asp
To configure URLScan to prohibit DOS reserved filenames, add the following entries to the urlscan.ini file
located in C:\WINNT\system32\inetsrv\urlscan.
| [DenyUrlSequences] |
| /NUL. | ; Don't allow DOS reserved filenames as valid files |
| /COM1. |
| /COM2. |
| /COM3. |
| /LPT1. |
| /LPT2. |
| /PRN. |
| /AUX. |
Method 2 - IIS Check that file exists
In the IIS Properties dialog:
| choose: | Master Properties for [WWW Service] |
| select: | [Edit] |
| select: | [Home Directory] tab |
| select: | [Configuration] button |
| find: | Application Mappings for:.cfm C:\CFUSION\bin\iscf.dll ALL |
| select: | [Edit] |
| enable: | [Check that file exists] checkbox |
| select: | [OK] |
When prompted - apply this change to all virtual directories which
can contain ColdFusion templates |
Repeat this procedure to change the Application Mappings for:
.dbm C:\CFUSION\bin\iscf.dll ALL |
This second method may have two disadvantages:
- The IIS error page will display for non-existent template, instead of the ColdFusion error page
- CFGRAPH cannot be used to create graphs as .jpg (JPEG) files
Affected Software Versions
- ColdFusion Server for Windows 4.x , 5 (All Editions)
What Macromedia is Doing
Macromedia has notified customers of the security issues through standard
communication channels.
What Customers Should Do
Customers are advised to implement one of the two methods described if disclosure of the
IIS web root is a security concern.
Revisions
May 9, 2002 -- Bulletin first created.
Reporting Security Issues
Credit
Macromedia would like to thank KPMG in Frederiksberg, Denmark for bringing this to our attention.
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