# AWS - Federation Abuse
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## SAML
For info about SAML please check:
{% embed url="https://book.hacktricks.xyz/pentesting-web/saml-attacks" %}
In order to configure an **Identity Federation through SAML** you just need to provide a **name** and the **metadata XML** containing all the SAML configuration (**endpoints**, **certificate** with public key)
## OIDC - Github Actions Abuse
In order to add a github action as Identity provider:
1. For _Provider type_, select **OpenID Connect**.
2. For _Provider URL_, enter `https://token.actions.githubusercontent.com`
3. Click on _Get thumbprint_ to get the thumbprint of the provider
4. For _Audience_, enter `sts.amazonaws.com`
5. Create a **new role** with the **permissions** the github action need and a **trust policy** that trust the provider like:
* ```json
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Principal": {
"Federated": "arn:aws:iam::0123456789:oidc-provider/token.actions.githubusercontent.com"
},
"Action": "sts:AssumeRoleWithWebIdentity",
"Condition": {
"StringEquals": {
"token.actions.githubusercontent.com:sub": [
"repo:ORG_OR_USER_NAME/REPOSITORY:pull_request",
"repo:ORG_OR_USER_NAME/REPOSITORY:ref:refs/heads/main"
],
"token.actions.githubusercontent.com:aud": "sts.amazonaws.com"
}
}
}
]
}
```
6. Note in the previous policy how only a **branch** from **repository** of an **organization** was authorized with a specific **trigger**.
7. The **ARN** of the **role** the github action is going to be able to **impersonate** is going to be the "secret" the github action needs to know, so **store** it inside a **secret** inside an **environment**.
8. Finally use a github action to configure the AWS creds to be used by the workflow:
```yaml
name: 'test AWS Access'
# The workflow should only trigger on pull requests to the main branch
on:
pull_request:
branches:
- main
# Required to get the ID Token that will be used for OIDC
permissions:
id-token: write
contents: read # needed for private repos to checkout
jobs:
aws:
runs-on: ubuntu-latest
steps:
- name: Checkout
uses: actions/checkout@v3
- name: Configure AWS Credentials
uses: aws-actions/configure-aws-credentials@v1
with:
aws-region: eu-west-1
role-to-assume: ${{ secrets.READ_ROLE }}
role-session-name: OIDCSession
- run: aws sts get-caller-identity
shell: bash
```
## OIDC - EKS Abuse
```bash
# Crate an EKS cluster (~10min)
eksctl create cluster --name demo --fargate
```
```bash
# Create an Identity Provider for an EKS cluster
eksctl utils associate-iam-oidc-provider --cluster Testing --approve
```
It's possible to generate **OIDC providers** in an **EKS** cluster simply by setting the **OIDC URL** of the cluster as a **new Open ID Identity provider**. This is a common default policy:
```json
{
"Version": "2012-10-17",
"Statement": [
{
"Effect": "Allow",
"Principal": {
"Federated": "arn:aws:iam::123456789098:oidc-provider/oidc.eks.us-east-1.amazonaws.com/id/20C159CDF6F2349B68846BEC03BE031B"
},
"Action": "sts:AssumeRoleWithWebIdentity",
"Condition": {
"StringEquals": {
"oidc.eks.us-east-1.amazonaws.com/id/20C159CDF6F2349B68846BEC03BE031B:aud": "sts.amazonaws.com"
}
}
}
]
}
```
This policy is correctly indicating than **only** the **EKS cluster** with **id** `20C159CDF6F2349B68846BEC03BE031B` can assume the role. However, it's not indicting which service account can assume it, which means that A**NY service account with a web identity token** is going to be **able to assume** the role.
In order to specify **which service account should be able to assume the role,** it's needed to specify a **condition** where the **service account name is specified**, such as:
{% code overflow="wrap" %}
```bash
"oidc.eks.region-code.amazonaws.com/id/20C159CDF6F2349B68846BEC03BE031B:sub": "system:serviceaccount:default:my-service-account",
```
{% endcode %}
## References
* [https://www.eliasbrange.dev/posts/secure-aws-deploys-from-github-actions-with-oidc/](https://www.eliasbrange.dev/posts/secure-aws-deploys-from-github-actions-with-oidc/)
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Support HackTricks
* Check the [**subscription plans**](https://github.com/sponsors/carlospolop)!
* **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)**.**
* **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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