Title: Flaw in Services for Unix 3.0 Interix SDK Could Allow Code Execution (Q329209) Released: 02 October 2002 Software: Services for Unix 3.0 Interix SDK Impact: Buffer overrun and denial of service Max Risk: Moderate Bulletin: MS02-057
Microsoft encourages customers to review the Security Bulletin at: http://www.microsoft.com/technet/security/bulletin/MS02-057.asp.
All three vulnerabilities discussed in this bulletin involve the inclusion of the Sun [TM] Microsystems 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 environ- ments. In version 3.0, the Interix subsystem technology is built in so that Windows Services for UNIX 3.0 can provide platform inter- operability 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 app- Lication 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.
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