Alert: Microsoft Security Bulletin - MS02-057

From: Russ (Russ.Cooper@RC.ON.CA)
Date: 10/03/02


Date:         Wed, 2 Oct 2002 23:35:50 -0400
From: Russ <Russ.Cooper@RC.ON.CA>
To: NTBUGTRAQ@LISTSERV.NTBUGTRAQ.COM

http://www.microsoft.com/technet/security/bulletin/MS02-057.asp

Flaw in Services for Unix 3.0 Interix SDK Could Allow Code Execution (Q329209)

Originally posted: October 02, 2002

Summary

Who should read this bulletin: Administrators and developers who have deployed applications or utilities using the Sun [TM] Microsystems RPC library on the Services for Unix 3.0 Interix SDK.

Impact of vulnerability: Denial of Service, run code of attacker's choice

Maximum Severity Rating: Moderate

Recommendation: Administrators who have deployed applications or utilities using the Sun Microsystems RPC library on the Interix SDK should apply the patch.

Affected Software: Only applications or utilities running on the following operating systems using the Sun Microsystem RPC library on the Services for Unix 3.0 Interix SDK should consider applying the patch.
- Microsoft Windows NT4
- Microsoft Windows 2000
- Microsoft Windows XP

Technical description:

All three vulnerabilities discussed in this bulletin involve the inclusion of the Sun RPC library in Microsoft's Services for UNIX (SFU) 3.0 on the Interix SDK. Developers who created applications or utilities using the Sun RPC library from the Interix SDK need to evaluate three vulnerabilities.

Windows Services for UNIX (SFU) 3.0 provides a full range of cross-platform services to integrate Windows into existing UNIX environments. In version 3.0, the Interix subsystem technology is built in so that Windows Services for UNIX 3.0 can provide platform interoperability and application migration in one fully integrated and supported product from Microsoft. Developers who have integrated Windows into their existing UNIX environments may have used the Interix SDK to develop custom applications and utilities so that applications that only ran on the UNIX platform can now run in a Windows environment. Developers who used the Interix SDK to develop applications or utilities should read this bulletin.

The first vulnerability is an integer overflow in the XDR library that ships with the Sun RPC library on the Interix SDK for Microsoft's Services for Unix (SFU) 3.0. An attacker could send a malicious RPC request to the RPC server from a remote machine and cause corruption in the server program. This can cause the server to fail and potentially allow the attacker to run code of his or her choice in the context of the server program.

The second vulnerability is a buffer overrun. An attacker could send a malicious RPC request to the RPC server with an improper parameter size check. This could lead to a buffer overrun, causing the server to fail and preventing it from servicing any further requests from clients.

The third vulnerability is an RPC implementation error. An application using the Sun RPC library does not properly check the size of client TCP requests. This could result in a denial of service to a server application using the Sun RPC library. The RPC library expects client TCP requests to specify the size of the record that follows. Because there is a flaw in the way RPC detects client packets, an attacker could send a malformed RPC request to the RPC server from a remote machine and cause the server to fail by not servicing any further client requests.

After applying the patch, it is necessary to recompile any Interix application that is statically linked with the Interix SDK Sun RPC library.

Mitigating factors:
- Only applications or utilities that were created using the Interix SDK and specifically that use the Sun RPC library, would be affected by these vulnerabilities.
- If an administrator or developer has only installed the Interix SDK but has not actually created applications with the SDK that use the Sun RPC library, the systems where the SDK was installed would not be vulnerable.

Vulnerability identifier:
- Integer Overflow in XDR library:CAN-2002-0391
- Improper parameter size check leading to buffer overrun:CAN-2002-1140
- RPC implementation error:CAN-2002-1141

This email is sent to NTBugtraq automatically as a service to my subscribers. Since its programmatically created, and since its been a long time since anyone paid actual money for my programming skills, it may or may not look that good...;-]

I can only hope that the information it does contain can be read well enough to serve its purpose.

Cheers,
Russ - Surgeon General of TruSecure Corporation/NTBugtraq Editor