MORE INFORMATION
Microsoft highly recommends that customers evaluate the degree of risk that this vulnerability poses to their systems and determine whether to download and install the fix.
This fix corrects the vulnerability by restricting ViewCode.asp to viewing only files in the current directory. However, Web site operators who do not have a need to provide the file viewing capability may choose to remove all copies ViewCode.asp from the server altogether.
Environment in Which ViewCode.asp May Cause Security Risk
The security exposure is limited to the situation in which all of the following is true:
- Servers that have the sample sites installed.
- The sample sites are not protected by ACLs.
- Sensitive data exists on the same logical drive as ViewCode.asp.
- Files containing sensitive data allow the "Everyone" user group read or greater access in the ACL.
- Malicious users know the path and filename of files that contain sensitive data.
Installing the Fix
The fix installation program, Update.exe, automatically replaces existing ViewCode.asp files.
NOTE: Common_viewcode.asp is used to replace the "common" ViewCode.asp file in the six directories listed below. PubSys_viewcode.asp is used to replace the existing ViewCode.asp in the Publishing sample (\Microsoft Site Server\SiteServer\Publishing).
Versions and Locations of ViewCode.asp
A complete installation of Site Server 3.0 will install various copies of ViewCode.asp in different directories. Therefore, if you to choose to remove it, perform a full-disk search to locate all copies.
The following six directories contain the same version of ViewCode.asp:
- \Microsoft Site Server\Sites\Knowledge\Membership\Inspired
- \Microsoft Site Server\Sites\Knowledge\Membership\Inspiredtutorial
- \Microsoft Site Server\Sites\Samples\Knowledge\Membership\Inspired
- \Microsoft Site Server\Sites\Samples\Knowledge\Membership\Inspiredtutorial
- \Microsoft Site Server\Sites\Samples\Knowledge\Push
- \Microsoft Site Server\Sites\Samples\Knowledge\Search
However, the Publishing sample (\Microsoft Site Server\SiteServer\Publishing) contains a different version of ViewCode.asp that is customized to work specifically with the Publishing samples, which allows the samples to work as properly, but prevents a malicious user from gaining access to files outside of the sample sites.
NOTE: ViewCode.asp should always have the ACL permissions
set to Administrators only, or to a group that is limited to Web content
developers.
Code Changes in the Fix
The issue is that ViewCode.asp uses "server.mappath" without any restrictions on what is passed to this function. Because ViewCode.asp allows a user to enter a path and filename, a malicious user could gain access to, and read (read-only), any known file on the same logical disk as ViewCode.asp that is not protected (no ACLs set for it).
The code added to the InitFileReading function in ViewCode.asp is as follows (these lines of code may wrap):
'Limit function to .asp and .vbo files in current and child directories
If instr(1, strVirtualPath, "..", 1) <> 0 Then
Response.Write("<HR> The path to the requested file cannot be mapped.<HR>")
fFileError = TRUE
ElseIf instr(1, strVirtualPath, ".asp", 1) = 0 And instr(1, strVirtualPath, ".vbo", 1) = 0 Then
Response.Write("<HR> The path to the requested file cannot be mapped.<HR>")
fFileError = TRUE
ElseIf Left( strVirtualPath, 1) = "/" or Left( strVirtualPath, 1) = "\" Then
If instr(1, strVirtualPath, "/siteserver/publishing", 1) = 0 And instr(1, strVirtualPath, "/sites/knowledge/membership", 1) = 0 And instr(1, strVirtualPath, "/sites/samples/knowledge", 1) = 0 Then
Response.Write("<HR> The path to the requested file cannot be mapped.<HR>")
fFileError = TRUE
End If
End If
For the Publishing sample sites, a slightly different modification is required (these lines of code may wrap):
'Limit function to .asp, .vbo, .inc, .txt, and .prf files in current, cmsample, fpsample, and child directories
If instr(1, strVirtualPath, "..", 1) <> 0 Then
Response.Write("<HR> The path to the requested file cannot be mapped.<HR>")
fFileError = TRUE
ElseIf instr(1, strVirtualPath, ".asp", 1) = 0 And instr(1, strVirtualPath, ".vbo", 1) = 0 And instr(1, strVirtualPath, ".inc", 1) = 0 And instr(1, strVirtualPath, ".txt", 1) = 0 And instr(1, strVirtualPath, ".prf", 1) = 0 Then
Response.Write("<HR> The path to the requested file cannot be mapped.<HR>")
fFileError = TRUE
ElseIf Left( strVirtualPath, 1) = "/" or Left( strVirtualPath, 1) = "\" Then
If instr(1, strVirtualPath, "/siteserver/publishing", 1) = 0 And instr(1, strVirtualPath, "/cmsample", 1) = 0 And instr(1, strVirtualPath, "/fpsample", 1) = 0 Then
Response.Write("<HR> The path to the requested file cannot be mapped.<HR>")
fFileError = TRUE
End If
End If
Purpose of ViewCode.asp & Related MSDN Sample
The purpose of ViewCode.asp is to show the Web content developer the code that makes the sample sites work. This type of function is also used on the Web author's workshop on the MSDN site (
http://msdn.microsoft.com/workshop/c-frame.htm#/workshop/author/default.asp).
If you base your content on one of the sample sites, remove the buttons (links) that load the code into ViewCode.asp to display it.
About Installing Samples & Documentation on Production Servers
Most Site Server users do not install the sample sites on their production servers, just as they do not install the documentation. They are not typically needed on the production servers, as they use additional disk space, and because of the fact that they are just samples, they may not be secure as needed in a production environment.
If you have a need to include the samples on a production server, however, consider restricting access to them to your developers only.
Additional References
Please see the following reference for more information related to this issue:
For additional security-related information about Microsoft products, please visit
http://www.microsoft.com/security.