Trusting Domain May Allow Privilege Elevation from Trusted Domain User (305330)

SYMPTOMS

When a user in a trusted domain requests access to a resource in a trusting domain, the trusted domain supplies authorization data in the form of a list of security identifiers (SIDs) that indicate the user's identity and group memberships. The trusting domain uses this data to determine whether to grant the user's request.

It may be possible for someone to insert SIDs of his or her choice in the authorization data at the trusted domain and elevate his or her privileges to those that are associated with any user or group, including the Domain Administrators group for the trusting domain. This would enable the attacker to gain full domain administrator access on computers in the trusting domain.

RESOLUTION

To resolve this problem, either obtain Windows 2000 Service Pack 3 or Windows 2000 Security Rollup Package 1 (SRP1). 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:

260910 How to Obtain the Latest Windows 2000 Service Pack

For additional information about SRP1, click the article number below to view the article in the Microsoft Knowledge Base:

311401 Windows 2000 Security Rollup Package 1 (SRP1), January 2002

Microsoft has developed a SID Filtering mechanism that eliminates this vulnerability and adds further protection between trusting domains. When SID Filtering is installed and enabled on the domain controllers of a trusting domain, it causes Windows to inspect all incoming authorization data and remove any SIDs that do not identify a user or security group that is defined in the trusted domain.

The following file is available for download from the Microsoft Download Center:

Download Readme.exe now

Release Date: September 6, 2001

For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base:

119591 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 security-enhanced servers that help to 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
     ---------------------------------------------------
     07-Aug-2001   18:11   505,616   Lsasrv.dll (56-bit)
     07-Aug-2001   18:28   355,088   Advapi32.dll
     07-Aug-2001   18:28   135,440   Dnsapi.dll
     07-Aug-2001   18:28    94,992   Dnsrslvr.dll
     07-Aug-2001   18:22   523,024   Instlsa5.dll
     07-Aug-2001   18:28   143,120   Kdcsvc.dll
     07-Aug-2001   11:03   197,392   Kerberos.dll
     26-Jun02001   20:16    69,456   Ksecdd.sys
     07-Aug-2001   18:11   505,104   Lsasrv.dll
     07-Aug-2001   18:11    33,552   Lsass.exe
     07-Aug-2001   18:28   306,448   Netapi32.dll
     07-Aug-2001   18:28   358,160   Netlogon.dll
     07-Aug-2001   18:28   909,072   Ntdsa.dll
     07-Aug-2001   18:28   386,320   Samsrv.dll
     07-Aug-2001   18:28   128,784   Scecli.dll
     07-Aug-2001   18:28   299,792   Scesrv.dll
     07-Aug-2001   18:28    48,400   W32time.dll
     01-Aug-2001   21:44    56,592   W32tm.exe

NOTE: Due to file dependencies, this update requires Windows 2000 Service Pack 2.

MORE INFORMATION

For more information on this vulnerability, see the following Microsoft Web site:

http://www.microsoft.com/technet/security/bulletin/ms02-0xx.asp

Exploiting this vulnerability would be difficult. At a minimum, an attacker would need administrative privileges on the trusted domain, and the technical wherewithal to modify low-level operating system functions and data structures.

Windows NT 4.0 provides no mechanism by which additional SIDs could be added to authorization data. To exploit the vulnerability, an attacker would need to develop and install custom operating system components to add the SIDs.
Windows 2000 does provide a mechanism known as SIDHistory for introducing additional SIDs in authorization data. However, there is no programming interface that would allow an attacker (even with administrative rights) to introduce a SID into the SIDHistory information; instead, an attacker would need to perform a binary edit of the data structures that hold the SIDHistory information.

Mitigating Factors

The attacker would need to have domain administrator privileges in the trusted domain to exploit the vulnerability.
The attacker's domain would need to already be trusted by the target domain, or the target domain's administrator would need to approve the establishment of a new trust relationship. There is no capability for the attacker to unilaterally initiate a trust relationship with another domain or cause it to trust the attacker's domain.
The attacker would need to modify operating system components and data.

For additional information about how to obtain a hotfix for Windows 2000 Datacenter Server, click the article number below to view the article in the Microsoft Knowledge Base:

265173 The Datacenter Program and Windows 2000 Datacenter Server Product

For additional information about how to install multiple hotfixes with only one reboot, click the article number below to view the article in the Microsoft Knowledge Base:

296861 Use QChain.exe to Install Multiple Hotfixes with One Reboot