Q274149: Cookies Are Not Marked as Secure in IIS
Article: Q274149
Product(s): Internet Information Server
Version(s): 4.0,5.0
Operating System(s):
Keyword(s): kbSecurity kbWinNT400PreSP7Fix kbWin2000PreSP2Fix kbWin2000SP2Fix kbgraphxlinkcritical
Last Modified: 15-AUG-2002
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The information in this article applies to:
- Microsoft Internet Information Server version 4.0
- Microsoft Internet Information Services version 5.0
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SYMPTOMS
========
When you use Active Server Pages (ASP) in Internet Information Server (IIS) 4.0
or Internet Information Services (IIS) 5.0, a session cookie is sent to a user's
browser. This cookie identifies the user for the time that they are on the site.
These cookies are sometimes called memory cookies, because they are never stored
on the user's hard drive like a regular cookie. In reality, this is an
additional header that is sent to the browser. Anytime a Web site sends
additional information such as this, the browser is required to send it back
with each request (provided the server name does not change). The following is
an example of an ASP Session Cookie:
Set-Cookie: ASPSESSIONIDGQQGGLIC=HKEDPNNBNBBKMOCFFBEIJENM; path=/
HTTP is a stateless protocol, which means that every time a user connects to a
Web site it is just like the first time they connected to the Web server. This
is a problem in an environment where you store server-side information for
users. The session cookie is a means of performing such tasks.
A problem can occur if developers decide to store confidential or sensitive
information in the session. For example, if a developer writes a piece of ASP
code that requests a user's credit card number, the developer can store this
information in a session variable (session variables are linked to the session
cookie) on the server. The user can then browse to a page that lists the
information they entered (for example, an authorization page or an order
confirmation page). The credit card (when the list is generated) may be pulled
from a session variable. If so, this information may be at risk.
If a malicious user performs a network trace or something similar, they could
possibly obtain the session cookie from the user's browser when it is sent back
to the server. If the malicious user makes a request to the server and presents
that cookie (or actually replays the request), they could effectively see that
users information stored in the session variables. The malicious user only needs
to know the page that generated the output (for example, the order confirmation
page).
Microsoft recommends that developers use SSL to encrypt sensitive information in
order to hide the session cookie. In most cases, this will work fine; however,
if the user goes from an HTTPS (secured) connection, and then back to HTTP
(non-secured), the cookie is readable. This presents a problem, because the
session cookie issued by a secured and non-secured request is the same.
CAUSE
=====
Microsoft has determined this to be a problem in IIS 4.0 and 5.0. The cookie
specification in RFC 2109 states that a cookie may be marked as Secure. IIS does
not differentiate between secure and non-secure cookies.
RESOLUTION
==========
For IIS 5.0 (Windows 2000):
To resolve this problem, obtain the latest service pack for Windows 2000. For
additional information, click the following article number to view the article
in the Microsoft Knowledge Base:
Q260910 How to Obtain the Latest Windows 2000 Service Pack
The following file is available for download from the Microsoft Download Center:
DownloadDownload Q274149_W2K_SP2_x86_en.exe now
(http://www.microsoft.com/Windows2000/downloads/critical/q274149/default.asp)
NOTE: After you apply the patch, run the following commands to enable secure
cookies (this example enables them for site 1):
"cd %windir%\system32\inetsrv\adminsamples" (without the quotation marks)
"adsutil set w3svc/1/AspKeepSessionIDSecure 1" (without the quotation marks)
For additional information about how to download Microsoft Support files, click
the following article number to view the article in the Microsoft Knowledge
Base:
Q119591 How to Obtain Microsoft Support Files from Online Services
Microsoft scanned this file for viruses. Microsoft used the most current
virus-detection software that was available on the date that the file was
posted. The file is stored on secure servers that prevent any unauthorized
changes to the file.
The English version of this fix should have the following file attributes or
later:
Date Time Version Size File name
-----------------------------------------------------------------
5/31/2001 03:31p 5.0.2195.3649 245,520 Adsiis.dll
5/31/2001 03:31p 5.0.2195.3649 332,560 Asp.dll
5/31/2001 03:31p 5.0.2195.3649 13,584 Infoadmn.dll
5/31/2001 03:31p 5.0.2195.3649 245,520 Infocomm.dll
5/31/2001 03:31p 5.0.2195.3649 62,736 Isatq.dll
5/30/2001 03:40p 5.0.2195.3651 6,928 Schmupd.exe
5/31/2001 03:32p 5.0.2195.3649 7,440 W3ctrs.dll
For IIS 4.0 (Windows NT Server 4.0):
A supported fix is now available from Microsoft, but it is only intended to
correct the problem that is described in this article. Apply it only to
computers that you determine are at risk of attack. Evaluate your computer's
physical accessibility, network and Internet connectivity, and other factors to
determine the degree of risk to your computer. See the associated Microsoft
Security Bulletin () to help determine the degree of risk. This fix may receive
additional testing. If your computer is sufficiently at risk, Microsoft
recommends that you apply this fix now.
To resolve this problem immediately, download the fix by clicking the download
link later in this article or contact Microsoft Product Support Services to
obtain the fix. For a complete list of Microsoft Product Support Services phone
numbers and information about support costs, please visit the following
Microsoft Web site:
http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS
NOTE: In special cases, charges that are ordinarily incurred for support calls
may be canceled, if a Microsoft Support Professional determines that a specific
update will resolve your problem. The usual support costs will apply to
additional support questions and issues that do not qualify for the specific
update in question.
The following file is available for download from the Microsoft Download Center:
DownloadDownload Secsesi.exe now
(http://www.microsoft.com/ntserver/nts/downloads/critical/q274149/default.asp)
NOTE: After applying the patch, run the following commands to enable secure
cookies (this example enables them for site 1):
cd %windir%\system32\inetsrv\adminsamples
adsutil set w3svc/1/AspKeepSessionIDSecure 1
For additional information about how to download Microsoft Support files, click
the following article number to view the article in the Microsoft Knowledge
Base:
Q119591 How to Obtain Microsoft Support Files from Online Services
Microsoft scanned this file for viruses. Microsoft used the most current
virus-detection software that was available on the date that the file was
posted. The file is stored on secure servers that prevent any unauthorized
changes to the file.
The English version of this fix should have the following file attributes or
later:
Date Time Size File name
-----------------------------------------
11/08/2000 03:29p 214,544 Adsiis.dll
11/09/2000 05:32p 330,672 Asp.dll
11/08/2000 02:39p 11,396 Httpext.h
11/09/2000 05:38p 55,904 Httpodbc.dll
11/08/2000 03:29p 98,912 Iischema.dll
11/08/2000 02:39p 28,851 Iiscnfg.h
11/08/2000 03:27p 185,792 Infocomm.dll
11/08/2000 03:32p 9,680 Schmupd.exe
11/09/2000 05:38p 38,256 Ssinc.dll
11/08/2000 03:28p 25,360 Sspifilt.dll
11/09/2000 05:37p 229,008 W3svc.dll
Windows NT Server version 4.0, Terminal Server Edition
To resolve this problem, obtain the Windows NT Server 4.0, Terminal Server
Edition, Security Rollup Package (SRP). For additional information about the
SRP, click the article number below to view the article in the Microsoft
Knowledge Base:
Q317636 Windows NT Server 4.0, Terminal Server Edition, Security Rollup
Package
STATUS
======
Microsoft has confirmed that this is a problem in the Microsoft products that
are listed at the beginning of this article.
Microsoft has confirmed that this problem may cause a degree of security
vulnerability in IIS 5.0 and IIS 4.0. This problem was first corrected in
Windows 2000 Service Pack 3.
MORE INFORMATION
================
For more information about ASP and session state, see the following MSDN
article:
http://msdn.microsoft.com/workshop/server/asp/active.asp
Additional query words:
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Keywords : kbSecurity kbWinNT400PreSP7Fix kbWin2000PreSP2Fix kbWin2000SP2Fix kbgraphxlinkcritical kbWin2000sp3fix
Technology : kbiisSearch kbiis500 kbiis400
Version : :4.0,5.0
Hardware : x86
Issue type : kbbug
Solution Type : kbfix
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