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Microsoft Office / COM Object DLL Planting

Posted by deepcore on December 15, 2015 – 9:17 pm

It is possible for an attacker to execute a DLL planting attack in Microsoft Office 2010 on Windows 7 x86 with a specially crafted OLE object. This attack also works on Office 2013 running on Windows 7 x64. Other platforms were not tested. The attached POC document “planted-mqrt.doc” contains what was originally an embedded Packager object. The CLSID for this object was changed at offset 0x2650 to be {ecabafc9-7f19-11d2-978e-0000f8757e2a} (formatted as pack(“>IHHBBBBBBBB”)). This object has a InProcServer32 pointing to comsvcs.dll. Specifically the CQueueAdmin object implemented in the dll. When a user opens this document and single clicks on the icon for foo.txt ole32!OleLoad is invoked on our vulnerable CLSID. This results in a call to a class factory constructor that tries eventually tries to call mqrt!MQGetPrivateComputerInformation. Because mqrt is a delay loaded dll the loader has inserted a stub to call _tailMerge_mqrt_dll on the first call of this function. This results in a kernelbase!LoadLibraryExA call vulnerable to dll planting. If the attached mqrt.dll is placed in the same directory with the planted-mqrt.doc file you should see a popup coming from this DLL being loaded from the current working directory of Word.


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