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79 lines
6.4 KiB
Markdown
79 lines
6.4 KiB
Markdown
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# macOS Office Sandbox Bypasses
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{% hint style="success" %}
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Learn & practice AWS Hacking:<img src="/.gitbook/assets/arte.png" alt="" data-size="line">[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte)<img src="/.gitbook/assets/arte.png" alt="" data-size="line">\
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Learn & practice GCP Hacking: <img src="/.gitbook/assets/grte.png" alt="" data-size="line">[**HackTricks Training GCP Red Team Expert (GRTE)**<img src="/.gitbook/assets/grte.png" alt="" data-size="line">](https://training.hacktricks.xyz/courses/grte)
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<details>
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<summary>Support HackTricks</summary>
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* Check the [**subscription plans**](https://github.com/sponsors/carlospolop)!
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* **Join the** 💬 [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** us on **Twitter** 🐦 [**@hacktricks\_live**](https://twitter.com/hacktricks\_live)**.**
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* **Share hacking tricks by submitting PRs to the** [**HackTricks**](https://github.com/carlospolop/hacktricks) and [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) github repos.
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</details>
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{% endhint %}
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### Word Sandbox bypass via Launch Agents
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The application uses a **custom Sandbox** using the entitlement **`com.apple.security.temporary-exception.sbpl`** and this custom sandbox allows to write files anywhere as long as the filename started with `~$`: `(require-any (require-all (vnode-type REGULAR-FILE) (regex #"(^|/)~$[^/]+$")))`
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Therefore, escaping was as easy as **writing a `plist`** LaunchAgent in `~/Library/LaunchAgents/~$escape.plist`.
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Check the [**original report here**](https://www.mdsec.co.uk/2018/08/escaping-the-sandbox-microsoft-office-on-macos/).
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### Word Sandbox bypass via Login Items and zip
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Remember that from the first escape, Word can write arbitrary files whose name start with `~$` although after the patch of the previous vuln it wasn't possible to write in `/Library/Application Scripts` or in `/Library/LaunchAgents`.
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It was discovered that from within the sandbox it's possible to create a **Login Item** (apps that will be executed when the user logs in). However, these apps **won't execute unless** they are **notarized** and it's **not possible to add args** (so you cannot just run a reverse shell using **`bash`**).
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From the previous Sandbox bypass, Microsoft disabled the option to write files in `~/Library/LaunchAgents`. However, it was discovered that if you put a **zip file as a Login Item** the `Archive Utility` will just **unzip** it on its current location. So, because by default the folder `LaunchAgents` from `~/Library` is not created, it was possible to **zip a plist in `LaunchAgents/~$escape.plist`** and **place** the zip file in **`~/Library`** so when decompress it will reach the persistence destination.
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Check the [**original report here**](https://objective-see.org/blog/blog\_0x4B.html).
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### Word Sandbox bypass via Login Items and .zshenv
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(Remember that from the first escape, Word can write arbitrary files whose name start with `~$`).
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However, the previous technique had a limitation, if the folder **`~/Library/LaunchAgents`** exists because some other software created it, it would fail. So a different Login Items chain was discovered for this.
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An attacker could create the the files **`.bash_profile`** and **`.zshenv`** with the payload to execute and then zip them and **write the zip in the victims** user folder: **`~/~$escape.zip`**.
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Then, add the zip file to the **Login Items** and then the **`Terminal`** app. When the user relogins, the zip file would be uncompressed in the users file, overwriting **`.bash_profile`** and **`.zshenv`** and therefore, the terminal will execute one of these files (depending if bash or zsh is used).
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Check the [**original report here**](https://desi-jarvis.medium.com/office365-macos-sandbox-escape-fcce4fa4123c).
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### Word Sandbox Bypass with Open and env variables
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From sandboxed processes it's still possible to invoke other processes using the **`open`** utility. Moreover, these processes will run **within their own sandbox**.
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It was discovered that the open utility has the **`--env`** option to run an app with **specific env** variables. Therefore, it was possible to create the **`.zshenv` file** within a folder **inside** the **sandbox** and the use `open` with `--env` setting the **`HOME` variable** to that folder opening that `Terminal` app, which will execute the `.zshenv` file (for some reason it was also needed to set the variable `__OSINSTALL_ENVIROMENT`).
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Check the [**original report here**](https://perception-point.io/blog/technical-analysis-of-cve-2021-30864/).
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### Word Sandbox Bypass with Open and stdin
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The **`open`** utility also supported the **`--stdin`** param (and after the previous bypass it was no longer possible to use `--env`).
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The thing is that even if **`python`** was signed by Apple, it **won't execute** a script with the **`quarantine`** attribute. However, it was possible to pass it a script from stdin so it won't check if it was quarantined or not: 
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1. Drop a **`~$exploit.py`** file with arbitrary Python commands.
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2. Run _open_ **`–stdin='~$exploit.py' -a Python`**, which runs the Python app with our dropped file serving as its standard input. Python happily runs our code, and since it’s a child process of _launchd_, it isn’t bound to Word’s sandbox rules.
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{% hint style="success" %}
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Learn & practice AWS Hacking:<img src="/.gitbook/assets/arte.png" alt="" data-size="line">[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte)<img src="/.gitbook/assets/arte.png" alt="" data-size="line">\
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Learn & practice GCP Hacking: <img src="/.gitbook/assets/grte.png" alt="" data-size="line">[**HackTricks Training GCP Red Team Expert (GRTE)**<img src="/.gitbook/assets/grte.png" alt="" data-size="line">](https://training.hacktricks.xyz/courses/grte)
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<details>
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<summary>Support HackTricks</summary>
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* Check the [**subscription plans**](https://github.com/sponsors/carlospolop)!
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* **Join the** 💬 [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** us on **Twitter** 🐦 [**@hacktricks\_live**](https://twitter.com/hacktricks\_live)**.**
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* **Share hacking tricks by submitting PRs to the** [**HackTricks**](https://github.com/carlospolop/hacktricks) and [**HackTricks Cloud**](https://github.com/carlospolop/hacktricks-cloud) github repos.
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</details>
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{% endhint %}
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