Applications that use Lightweight Directory Access Protocol (LDAP) over Secure Sockets Layer (SSL) do not perform revocation checking of the server certificate in Windows Server 2003 with Service Pack 1

You have certain applications that use the Windows Lightweight Directory Access Protocol (LDAP) APIs to access an LDAP directory over Secure Sockets Layer (SSL) on a Microsoft Windows Server 2003 Service Pack 1 (SP1)-based computer. However, these applications do not perform revocation checking of the certificate that is issued to the LDAP server.

This problem occurs because of the following reasons.

In a Windows operating system, Microsoft Security Channel (SChannel) implements SSL and Transport Layer Security (TLS). By default, SChannel does not perform revocation checking of server authentication certificates. However, developers can modify this behavior by setting the appropriate SChannel flags before it calls into the component.

Additionally, the Wldap32.dll file implements the LDAP API in Windows. Developers can use the Wldap32.dll file calls to connect to a directory server over SSL or over TLS. The Wldap32.dll file depends on SChannel to help provide security for these connections. When the Wldap32.dll file calls into SChannel, the Wldap32.dll file does not modify the default behavior of SChannel authentication.

Therefore, when you use the Wldap32.dll file to connect to a directory server over SSL or TLS, the client computer does not perform revocation checking of the server authentication certificate.

Service pack information

To resolve this problem, obtain the latest service pack for Windows Server 2003. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Prerequisites

You must have Windows Server 2003 SP1 installed to apply this hotfix.

Restart requirement

You must restart your computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

Windows Server 2003 with SP1, x86-based versions

Windows Server 2003 with SP1, x64-based versions

Windows Server 2003 with SP1, Itanium-based versions

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section. This problem was first corrected in Windows Server 2003 Service Pack 2.

After you apply this hotfix, a code change occurs in the Wldap32.dll file. This code change lets developers modify how the Wldap32.dll file uses SChannel. Additionally, there is a new LDAP session option that lets developers set the SChannel flags.

The new LDAP session option is as follows:For more information about how to set LDAP session options, visit the following Microsoft Developer Network (MSDN) Web site:If the LDAP_OPT_SCH_FLAGS option is not set, the default SChannel flags that are used by the Wldap32.dll file are as follows:For more information about SChannel flags, visit the following Microsoft MSDN Web site:Note This change in behavior does not affect applications that are already compiled and installed. This article describes functionality that can now be applied in Windows Server 2003 Service Pack 2 (SP2). For more information, click the following article number to view the article in the Microsoft Knowledge Base: