Microsoft Windows RPC service vulnerable to DoS via NULL pointer dereference

Overview

The RPC service in Microsoft Windows NT 4.0, 2000, and XP can be terminated by a specially crafted RPC message. A remote attacker could cause a denial of service.

Description

According to Microsoft Security Bulletin MS03-010, “Remote Procedure Call (RPC) is a protocol used by the Windows operating system. RPC provides an inter-process communication mechanism that allows a program running on one computer to seamlessly execute code on a remote system.”

A vulnerability exists in a part of the RPC service called the RPC Endpoint Mapper. The RPC Endpoint Mapper listens for network requests (135/tcp), provides clients with port numbers for RPC services, and maintains information about RPC connections. According to a report from Immunity Security, vulnerable code in the RPC Endpoint Mapper dereferences a NULL pointer when processing a malformed RPC message.

---

Impact

An unauthenticated, remote attacker could cause the RPC Endpoint Mapper to terminate, denying service to legitimate users. Since the RPC Endpoint Mapper is part of the RPC service, “…exploiting this vulnerability would cause the RPC service to fail, with the attendant loss of any RPC-based services the server offers, as well as potential loss of some COM functions.”
Once the RPC service has been terminated, an attacker may be able to take control over an orphaned named pipe and gain the privileges of the RPC service (Local System).

---

Solution

Apply Patch
Apply the appropriate patch (Q331953) as specified in MS03-010. Microsoft notes that a patch will not be produced for Windows NT 4.0 or Windows NT 4.0 Terminal Server Edition.
The patches may cause local COM calls to fail, which could affect ASP/COM+ applications. See Microsoft Knowledgebase Article 814119 for more information.

---

Block or Restrict Access

Block or restrict access to the RPC Endpoint Mapper service (135/tcp) from untrusted networks such as the Internet.

---

Vendor Information

261537

Filter by status: All Affected Not Affected Unknown

Filter by content: __ Additional information available

__ Sort by: Status Alphabetical

Expand all

Javascript is disabled. Click here to view vendors.

Microsoft Corporation __ Affected

Updated: March 26, 2003

Status

Affected

Vendor Statement

We have not received a statement from the vendor.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

Please see MS03-010.

If you have feedback, comments, or additional information about this vulnerability, please send us [email](<mailto:[email protected]?Subject=VU%23261537 Feedback>).

CVSS Metrics

Group	Score	Vector
Base
Temporal
Environmental

References

• <http://www.immunitysec.com/vulnerabilities/Immunity_svchost_DoS.txt&gt;
• <http://www.securityfocus.com/bid/6005&gt;
• <http://www.securityfocus.com/bid/6769&gt;
• <http://www.securityfocus.com/archive/1/296114&gt;
• <http://www.microsoft.com/technet/security/bulletin/MS03-010.asp&gt;
• <http://support.microsoft.com/default.aspx?scid=kb;en-us;331953&gt;
• <http://support.microsoft.com/?kbid=814119&gt;
• <http://msdn.microsoft.com/library/default.asp?url=/library/en-us/rpc/rpc/how_rpc_works.asp&gt;

Acknowledgements

This vulnerability was publicly reported by Dave Aitel of Immunity Security.

This document was written by Art A Manion.

Other Information

CVE IDs:	CVE-2002-1561
Severity Metric:	23.69 Date Public: