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hacktricks/macos-hardening/macos-security-and-privilege-escalation/macos-tcc.md

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GITBOOK-3952: change request with no subject merged in GitBook
2023-05-28 15:30:30 +00:00
# macOS TCC
<details>
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</details>
## **Basic Information**
**TCC (Transparency, Consent, and Control)** is a mechanism in macOS to **limit and control application access to certain features**, usually from a privacy perspective. This can include things such as location services, contacts, photos, microphone, camera, accessibility, full disk access, and a bunch more.
From a user’s perspective, they see TCC in action **when an application wants access to one of the features protected by TCC**. When this happens the **user is prompted** with a dialog asking them whether they want to allow access or not.
It's also possible to **grant apps access** to files by **explicit intents** from users for example when a user **drags\&drop a file into a program** (obviously the program should have access to it).
![An example of a TCC prompt](https://rainforest.engineering/images/posts/macos-tcc/tcc-prompt.png?1620047855)
**TCC** is handled by the **daemon** located in `/System/Library/PrivateFrameworks/TCC.framework/Resources/tccd`configured in `/System/Library/LaunchDaemons/com.apple.tccd.system.plist` (registering the mach service `com.apple.tccd.system`).
There is a **user-mode tccd** running per logged in user defined in `/System/Library/LaunchAgents/com.apple.tccd.plist` registering the mach services `com.apple.tccd` and `com.apple.usernotifications.delegate.com.apple.tccd`.
Permissions are **inherited from the parent** application and the **permissions** are **tracked** based on the **Bundle ID** and the **Developer ID**.
### TCC Database
The selections is then stored in the TCC system-wide database in **`/Library/Application Support/com.apple.TCC/TCC.db`** or in **`$HOME/Library/Application Support/com.apple.TCC/TCC.db`** for per-user preferences. The database is **protected from editing with SIP**(System Integrity Protection), but you can read them by granting **full disk access**.
{% hint style="info" %}
The **notification center UI** can make **changes in the system TCC database**:
{% code overflow="wrap" %}
```bash
codesign -dv --entitlements :- /System/Library/PrivateFrameworks/TCC.framework/Support/tccd
[..]
com.apple.private.security.storage.TCC
com.apple.private.tcc.allow
com.apple.private.tcc.manager
com.apple.rootless.storage.TCC
```
{% endcode %}
However, users can **delete or query rules** with the **`tccutil`** command line utility.
{% endhint %}
{% tabs %}
{% tab title="user DB" %}
```bash
sqlite3 ~/Library/Application\ Support/com.apple.TCC/TCC.db
sqlite> .schema
# Tables: admin, policies, active_policy, access, access_overrides, expired, active_policy_id
# The table access contains the permissions per services
sqlite> select service, client, auth_value, auth_reason from access;
kTCCServiceLiverpool|com.apple.syncdefaultsd|2|4
kTCCServiceSystemPolicyDownloadsFolder|com.tinyspeck.slackmacgap|2|2
kTCCServiceMicrophone|us.zoom.xos|2|2
[...]
# Check user approved permissions for telegram
sqlite> select * from access where client LIKE "%telegram%" and auth_value=2;
# Check user denied permissions for telegram
sqlite> select * from access where client LIKE "%telegram%" and auth_value=0;
```
{% endtab %}
{% tab title="system DB" %}
```bash
sqlite3 /Library/Application\ Support/com.apple.TCC/TCC.db
sqlite> .schema
# Tables: admin, policies, active_policy, access, access_overrides, expired, active_policy_id
# The table access contains the permissions per services
sqlite> select service, client, auth_value, auth_reason from access;
kTCCServiceLiverpool|com.apple.syncdefaultsd|2|4
kTCCServiceSystemPolicyDownloadsFolder|com.tinyspeck.slackmacgap|2|2
kTCCServiceMicrophone|us.zoom.xos|2|2
[...]
# Check user approved permissions for telegram
sqlite> select * from access where client LIKE "%telegram%" and auth_value=2;
# Check user denied permissions for telegram
sqlite> select * from access where client LIKE "%telegram%" and auth_value=0;
```
{% endtab %}
{% endtabs %}
{% hint style="success" %}
Checking both databases you can check the permissions an app has allowed, has forbidden, or doesn't have (it will ask for it).
{% endhint %}
* The **`auth_value`** can have different values: denied(0), unknown(1), allowed(2), or limited(3).
* The **`auth_reason`** can take the following values: Error(1), User Consent(2), User Set(3), System Set(4), Service Policy(5), MDM Policy(6), Override Policy(7), Missing usage string(8), Prompt Timeout(9), Preflight Unknown(10), Entitled(11), App Type Policy(12)
* For more information about the **other fields** of the table [**check this blog post**](https://www.rainforestqa.com/blog/macos-tcc-db-deep-dive).
{% hint style="info" %}
Some TCC permissions are: kTCCServiceAppleEvents, kTCCServiceCalendar, kTCCServicePhotos... There is no public list that defines all of them but you can check this [**list of known ones**](https://www.rainforestqa.com/blog/macos-tcc-db-deep-dive#service).
{% endhint %}
You could also check **already given permissions** to apps in `System Preferences --> Security & Privacy --> Privacy --> Files and Folders`.
### TCC Signature Checks
The TCC **database** stores the **Bundle ID** of the application, but it also **stores** **information** about the **signature** to **make sure** the App asking to use the a permission is the correct one.
{% code overflow="wrap" %}
```bash
# From sqlite
sqlite> select hex(csreq) from access where client="ru.keepcoder.Telegram";
#Get csreq
# From bash
echo FADE0C00000000CC000000010000000600000007000000060000000F0000000E000000000000000A2A864886F763640601090000000000000000000600000006000000060000000F0000000E000000010000000A2A864886F763640602060000000000000000000E000000000000000A2A864886F7636406010D0000000000000000000B000000000000000A7375626A6563742E4F550000000000010000000A364E33385657533542580000000000020000001572752E6B656570636F6465722E54656C656772616D000000 | xxd -r -p - > /tmp/telegram_csreq.bin
## Get signature checks
csreq -t -r /tmp/telegram_csreq.bin
(anchor apple generic and certificate leaf[field.1.2.840.113635.100.6.1.9] /* exists */ or anchor apple generic and certificate 1[field.1.2.840.113635.100.6.2.6] /* exists */ and certificate leaf[field.1.2.840.113635.100.6.1.13] /* exists */ and certificate leaf[subject.OU] = "6N38VWS5BX") and identifier "ru.keepcoder.Telegram"
```
{% endcode %}
### Entitlements
Apps **don't only need** to **request** and have been **granted access** to some resources, they also need to **have the relevant entitlements**.\
For example **Telegram** has the entitlement `com.apple.security.device.camera` to request **access to the camera**. An **app** that **doesn't** have this **entitlement won't be able** to access the camera (and the user won't be be even asked for the permissions).
However, for apps to **access** to **certain user folders**, such as `~/Desktop`, `~/Downloads` and `~/Documents`, they **don't need** to have any specific **entitlements.** The system will transparently handle access and **prompt the user** as needed.
Apple's apps **won’t generate prompts**. They contain **pre-granted rights** in their **entitlements** list, meaning they will **never generate a popup**, **nor** they will show up in any of the **TCC databases.** For example:
```bash
codesign -dv --entitlements :- /System/Applications/Calendar.app
[...]
<key>com.apple.private.tcc.allow</key>
<array>
<string>kTCCServiceReminders</string>
<string>kTCCServiceCalendar</string>
<string>kTCCServiceAddressBook</string>
</array>
```
This will avoid Calendar ask the user to access reminders, calendar and the address book.
### Sensitive unprotected places
* $HOME (itself)
* $HOME/.ssh, $HOME/.aws, etc
* /tmp
### User Intent / com.apple.macl
As mentioned previously, it possible to **grant access to an App to a file by drag\&dropping it to it**. This access won't be specified in any TCC database but as an **extended** **attribute of the file**. This attribute will **store the UUID** of the allowed app:
```bash
# Check extra access to the file
macl.command Desktop/private.txt
Filename,Header,App UUID
"Desktop/private.txt",0300,769FD8F1-90E0-3206-808C-A8947BEBD6C3
# Get the UUID of the app
otool -l /System/Applications/Utilities/Terminal.app/Contents/MacOS/Terminal| grep uuid
uuid 769FD8F1-90E0-3206-808C-A8947BEBD6C3
```
{% hint style="info" %}
It's curious that the **`com.apple.macl`** attribute is managed by the **Sandbox**, not tccd
{% endhint %}
The extended attribute `com.apple.macl` **can’t be cleared** like other extended attributes because it’s **protected by SIP**. However, as [**explained in this post**](https://www.brunerd.com/blog/2020/01/07/track-and-tackle-com-apple-macl/), it's possible to disable it **zipping** the file, **deleting** it and **unzipping** it.
## Bypasses
### SSH Bypass
By default an access via **SSH** will have **"Full Disk Access"**. In order to disable this you need to have it listed but disabled (removing it from the list won't remove those privileges):
![](<../../.gitbook/assets/image (569).png>)
Here you can find examples of how some **malwares have been able to bypass this protection**:
* [https://www.jamf.com/blog/zero-day-tcc-bypass-discovered-in-xcsset-malware/](https://www.jamf.com/blog/zero-day-tcc-bypass-discovered-in-xcsset-malware/)
### Electron Bypass
The JS code of an Electron App is not signed, so an attacker could move the app to a writable location, inject malicious JS code and launch that app and abuse the TCC permissions.
Electron is working on **`ElectronAsarIntegrity`** key in Info.plist that will contain a hash of the app.asar file to check the integrity of the JS code before executing it.
### Code Injection Bypass
I you manage to **inject code in a process** you will be able to abuse the TCC permissions of that process.
## References
* [**https://www.rainforestqa.com/blog/macos-tcc-db-deep-dive**](https://www.rainforestqa.com/blog/macos-tcc-db-deep-dive)
<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)
* Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
* **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>
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