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Microsoft Windows LPC heap overflow
January 10, 2005
Risk Level: High
Summary:
A local privilege elevation vulnerability exists on the Windows operating systems. This vulnerability allows any user to take complete control over the system and affects Windows NT, Windows 2000, Windows XP, and Windows 2003 (all service packs).
Versions Affected:
Microsoft Windows NT, Windows 2000, Windows XP, and Windows 2003 (all service packs).
Details:
The LPC (Local Procedure Call) mechanism is a type of interprocess communication used by the Windows operating systems. LPC is used to communicate between processes running on the same system while RPC (Remote Procedure Call) is used to communicate between processes on remote systems.
When a client process communicates with a server using LPC, the kernel fails to check that the server process has allocated enough memory before copying data sent by the client process. The native API used to connect to the LPC port is NtConnectPort. A parameter of the NtConnectPort API allows a buffer of up 260 bytes. When using this function the buffer is copied by the kernel from the client process to the server process memory ignoring the buffer size restriction which the server process set when calling NtCreatePort (the native API used to create LPC ports). This causes a heap corruption in the server process allowing arbitrary memory to be overwritten and can lead to arbitrary code execution.
Workaround:
None.
Fix:
Fix information is available at
http://www.microsoft.com/technet/security/bulletin/MS04-044.mspx.
Acknowledgement:
This vulnerability was discovered and researched by Cesar Cerrudo of
Application Security, Inc.
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