# macOS Sandbox

<details>

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## Basic Information

MacOS Sandbox (initially called Seatbelt) **limits applications** running inside the sandbox to the **allowed actions specified in the Sandbox profile** the app is running with. This helps to ensure that **the application will be accessing only expected resources**.

Any app with the **entitlement** **`com.apple.security.app-sandbox`** will be executed inside the sandbox. **Apple binaries** are usually executed inside a Sandbox and in order to publish inside the **App Store**, **this entitlement is mandatory**. So most applications will be executed inside the sandbox.

In order to control what a process can or cannot do the **Sandbox has hooks** in all **syscalls** across the kernel. **Depending** on the **entitlements** of the app the Sandbox will **allow** certain actions.

Some important components of the Sandbox are:

* The **kernel extension** `/System/Library/Extensions/Sandbox.kext`
* The **private framework** `/System/Library/PrivateFrameworks/AppSandbox.framework`
* A **daemon** running in userland `/usr/libexec/sandboxd`
* The **containers** `~/Library/Containers`

Inside the containers folder you can find **a folder for each app executed sandboxed** with the name of the bundle id:

```bash
ls -l ~/Library/Containers
total 0
drwx------@ 4 username  staff  128 May 23 20:20 com.apple.AMPArtworkAgent
drwx------@ 4 username  staff  128 May 23 20:13 com.apple.AMPDeviceDiscoveryAgent
drwx------@ 4 username  staff  128 Mar 24 18:03 com.apple.AVConference.Diagnostic
drwx------@ 4 username  staff  128 Mar 25 14:14 com.apple.Accessibility-Settings.extension
drwx------@ 4 username  staff  128 Mar 25 14:10 com.apple.ActionKit.BundledIntentHandler
[...]
```

Inside each bundle id folder you can find the **plist** and the **Data directory** of the App:

```bash
cd /Users/username/Library/Containers/com.apple.Safari
ls -la
total 104
drwx------@   4 username  staff    128 Mar 24 18:08 .
drwx------  348 username  staff  11136 May 23 20:57 ..
-rw-r--r--    1 username  staff  50214 Mar 24 18:08 .com.apple.containermanagerd.metadata.plist
drwx------   13 username  staff    416 Mar 24 18:05 Data

ls -l Data
total 0
drwxr-xr-x@  8 username  staff   256 Mar 24 18:08 CloudKit
lrwxr-xr-x   1 username  staff    19 Mar 24 18:02 Desktop -> ../../../../Desktop
drwx------   2 username  staff    64 Mar 24 18:02 Documents
lrwxr-xr-x   1 username  staff    21 Mar 24 18:02 Downloads -> ../../../../Downloads
drwx------  35 username  staff  1120 Mar 24 18:08 Library
lrwxr-xr-x   1 username  staff    18 Mar 24 18:02 Movies -> ../../../../Movies
lrwxr-xr-x   1 username  staff    17 Mar 24 18:02 Music -> ../../../../Music
lrwxr-xr-x   1 username  staff    20 Mar 24 18:02 Pictures -> ../../../../Pictures
drwx------   2 username  staff    64 Mar 24 18:02 SystemData
drwx------   2 username  staff    64 Mar 24 18:02 tmp
```

{% hint style="danger" %}
Note that even if the symlinks are there to "escape" from the Sandbox and access other folders, the App still needs to **have permissions** to access them. These permissions are inside the **`.plist`**.
{% endhint %}

```bash
# Get permissions
plutil -convert xml1 .com.apple.containermanagerd.metadata.plist -o -

# Binary sandbox profile
<key>SandboxProfileData</key>
<data>
AAAhAboBAAAAAAgAAABZAO4B5AHjBMkEQAUPBSsGPwsgASABHgEgASABHwEf...
		
# In this file you can find the entitlements:
<key>Entitlements</key>
	<dict>
		<key>com.apple.MobileAsset.PhishingImageClassifier2</key>
		<true/>
		<key>com.apple.accounts.appleaccount.fullaccess</key>
		<true/>
		<key>com.apple.appattest.spi</key>
		<true/>
		<key>keychain-access-groups</key>
		<array>
			<string>6N38VWS5BX.ru.keepcoder.Telegram</string>
			<string>6N38VWS5BX.ru.keepcoder.TelegramShare</string>
		</array>
[...]

# Some parameters
<key>Parameters</key>
	<dict>
		<key>_HOME</key>
		<string>/Users/username</string>
		<key>_UID</key>
		<string>501</string>
		<key>_USER</key>
		<string>username</string>
[...]

# The paths it can access
<key>RedirectablePaths</key>
	<array>
		<string>/Users/username/Downloads</string>
		<string>/Users/username/Documents</string>
		<string>/Users/username/Library/Calendars</string>
		<string>/Users/username/Desktop</string>
<key>RedirectedPaths</key>
	<array/>
[...]
```

{% hint style="warning" %}
Everything created/modified by a Sandboxed application will get the **quarantine attribut**e. This will prevent a sandbox space by triggering Gatekeeper if the sandbox app tries to execute something with **`open`**.
{% endhint %}

### Sandbox Profiles

The Sandbox profiles are configuration files that indicate what is going to be **allowed/forbidden** in that **Sandbox**. It uses the **Sandbox Profile Language (SBPL)**, which uses the [**Scheme**](https://en.wikipedia.org/wiki/Scheme\_\(programming\_language\)) programming language.

Here you can find an example:

```scheme
(version 1) ; First you get the version

(deny default) ; Then you shuold indicate the default action when no rule applies

(allow network*) ; You can use wildcards and allow everything

(allow file-read* ; You can specify where to apply the rule
    (subpath "/Users/username/")
    (literal "/tmp/afile")
    (regex #"^/private/etc/.*")
)

(allow mach-lookup
    (global-name "com.apple.analyticsd")
)
```

{% hint style="success" %}
Check this [**research**](https://reverse.put.as/2011/09/14/apple-sandbox-guide-v1-0/) **to check more actions that could be allowed or denied.**
{% endhint %}

Important **system services** also run inside their own custom **sandbox** such as the `mdnsresponder` service. You can view these custom **sandbox profiles** inside:

* **`/usr/share/sandbox`**
* **`/System/Library/Sandbox/Profiles`**&#x20;
* Other sandbox profiles can be checked in [https://github.com/s7ephen/OSX-Sandbox--Seatbelt--Profiles](https://github.com/s7ephen/OSX-Sandbox--Seatbelt--Profiles).

**App Store** apps use the **profile** **`/System/Library/Sandbox/Profiles/application.sb`**. You can check in this profile how entitlements such as **`com.apple.security.network.server`** allows a process to use the network.

SIP is a Sandbox profile called platform\_profile in /System/Library/Sandbox/rootless.conf

### Sandbox Profile Examples

To start an application with an **specific sandbox profile** you can use:

```bash
sandbox-exec -f example.sb /Path/To/The/Application
```

{% tabs %}
{% tab title="touch" %}
{% code title="touch.sb" %}
```scheme
(version 1)
(deny default)
(allow file* (literal "/tmp/hacktricks.txt"))
```
{% endcode %}

```bash
# This will fail because default is denied, so it cannot execute touch
sandbox-exec -f touch.sb touch /tmp/hacktricks.txt
# Check logs
log show --style syslog --predicate 'eventMessage contains[c] "sandbox"' --last 30s
[...]
2023-05-26 13:42:44.136082+0200  localhost kernel[0]: (Sandbox) Sandbox: sandbox-exec(41398) deny(1) process-exec* /usr/bin/touch
2023-05-26 13:42:44.136100+0200  localhost kernel[0]: (Sandbox) Sandbox: sandbox-exec(41398) deny(1) file-read-metadata /usr/bin/touch
2023-05-26 13:42:44.136321+0200  localhost kernel[0]: (Sandbox) Sandbox: sandbox-exec(41398) deny(1) file-read-metadata /var
2023-05-26 13:42:52.701382+0200  localhost kernel[0]: (Sandbox) 5 duplicate reports for Sandbox: sandbox-exec(41398) deny(1) file-read-metadata /var
[...]
```

{% code title="touch2.sb" %}
```scheme
(version 1)
(deny default)
(allow file* (literal "/tmp/hacktricks.txt"))
(allow process* (literal "/usr/bin/touch"))
; This will also fail because:
; 2023-05-26 13:44:59.840002+0200  localhost kernel[0]: (Sandbox) Sandbox: touch(41575) deny(1) file-read-metadata /usr/bin/touch
; 2023-05-26 13:44:59.840016+0200  localhost kernel[0]: (Sandbox) Sandbox: touch(41575) deny(1) file-read-data /usr/bin/touch
; 2023-05-26 13:44:59.840028+0200  localhost kernel[0]: (Sandbox) Sandbox: touch(41575) deny(1) file-read-data /usr/bin
; 2023-05-26 13:44:59.840034+0200  localhost kernel[0]: (Sandbox) Sandbox: touch(41575) deny(1) file-read-metadata /usr/lib/dyld
; 2023-05-26 13:44:59.840050+0200  localhost kernel[0]: (Sandbox) Sandbox: touch(41575) deny(1) sysctl-read kern.bootargs
; 2023-05-26 13:44:59.840061+0200  localhost kernel[0]: (Sandbox) Sandbox: touch(41575) deny(1) file-read-data /
```
{% endcode %}

{% code title="touch3.sb" %}
```scheme
(version 1)
(deny default)
(allow file* (literal "/private/tmp/hacktricks.txt"))
(allow process* (literal "/usr/bin/touch"))
(allow file-read-data (literal "/"))
; This one will work
```
{% endcode %}
{% endtab %}
{% endtabs %}

{% hint style="info" %}
Note that the **Apple-authored** **software** that runs on **Windows** **doesn’t have additional security precautions**, such as application sandboxing.
{% endhint %}

Bypasses examples:

* [https://lapcatsoftware.com/articles/sandbox-escape.html](https://lapcatsoftware.com/articles/sandbox-escape.html)
* [https://desi-jarvis.medium.com/office365-macos-sandbox-escape-fcce4fa4123c](https://desi-jarvis.medium.com/office365-macos-sandbox-escape-fcce4fa4123c) (they are able to write files outside the sandbox whose name starts with `~$`).

### MacOS Sandbox Profiles

macOS stores system sandbox profiles in two locations: **/usr/share/sandbox/** and **/System/Library/Sandbox/Profiles**.

And if a third-party application carry the _**com.apple.security.app-sandbox**_ entitlement, the system applies the **/System/Library/Sandbox/Profiles/application.sb** profile to that process.

### **iOS Sandbox Profile**

The default profile is called **container** and we don't have the SBPL text representation. In memory, this sandbox is represented as Allow/Deny binary tree for each permissions from the sandbox.

### Debug & Bypass Sandbox

**Processes are not born sandboxed on macOS: unlike iOS**, where the sandbox is applied by the kernel before the first instruction of a program executes, on macOS **a process must elect to place itself into the sandbox.**

Processes are automatically Sandboxed from userland when they start if they have the entitlement: `com.apple.security.app-sandbox`. For a detailed explanation of this process check:

{% content-ref url="macos-sandbox-debug-and-bypass/" %}
[macos-sandbox-debug-and-bypass](macos-sandbox-debug-and-bypass/)
{% endcontent-ref %}

### **Check PID Privileges**

[**According to this**](https://www.youtube.com/watch?v=mG715HcDgO8\&t=3011s), the **`sandbox_check`** (it's a `__mac_syscall`), can check **if an operation is allowed or not** by the sandbox in a certain PID.

The [**tool sbtool**](http://newosxbook.com/src.jl?tree=listings\&file=sbtool.c) can check if a PID can perform a certain action:

```bash
sbtool <pid> mach #Check mac-ports (got from launchd with an api)
sbtool <pid> file /tmp #Check file access
sbtool <pid> inspect #Gives you an explaination of the sandbox profile
sbtool <pid> all
```

### Custom SBPL in App Store apps

It could be possible for companies to make their apps run **with custom Sandbox profiles** (instead of with the default one). They need to use the entitlement **`com.apple.security.temporary-exception.sbpl`** which needs to be authorized by Apple.

It's possible to check the definition of this entitlement in **`/System/Library/Sandbox/Profiles/application.sb:`**

```scheme
(sandbox-array-entitlement
  "com.apple.security.temporary-exception.sbpl"
  (lambda (string)
    (let* ((port (open-input-string string)) (sbpl (read port)))
      (with-transparent-redirection (eval sbpl)))))
```

This will **eval the string after this entitlement** as an Sandbox profile.

<details>

<summary><a href="https://cloud.hacktricks.xyz/pentesting-cloud/pentesting-cloud-methodology"><strong>☁️ HackTricks Cloud ☁️</strong></a> -<a href="https://twitter.com/hacktricks_live"><strong>🐦 Twitter 🐦</strong></a> - <a href="https://www.twitch.tv/hacktricks_live/schedule"><strong>🎙️ Twitch 🎙️</strong></a> - <a href="https://www.youtube.com/@hacktricks_LIVE"><strong>🎥 Youtube 🎥</strong></a></summary>

* 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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* **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/hacktricks\_live)**.**
* **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).

</details>