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This repository contains a Java adoption of the original OWASP Serverless Goat application.

Introduction

Thank you for using OWASP ServerlessGoat!

This serverless application demonstrates common serverless security flaws as described in the official OWASP Top 10 Serverless Interpretations and the Serverless Security Top 10 Weaknesses guide https://github.com/puresec/sas-top-10.

ServerlessGoat was created for the following educational purposes:

  • Teach developers & security practitioners about common serverless application layer risks and weaknesses
  • Educate on how serverless application layer weaknesses can be exploited
  • Teach developers & security practitioners about serverless security best-practices

You can find more information about WebGoat at: https://www.owasp.org/index.php/OWASP_Serverless_Goat

​WARNING 1: This application contains vulnerabilities. Use it only for training purposes.
WARNING 2: This program is for educational purposes only. Do not attempt these techniques without authorization from application owners. ​

NOTE: The application was developed in such way that should not put your AWS account at risk. The vulnerabilities that were introduced are contained within the boundaries of this specific application. Nevertheless, users are not encouraged to deploy the application in production environments.

Deployment

Prebuild

  1. Make sure you are logged into your AWS account
  2. Click on the following link: AWS Serverless Application Repository
  3. Click Deploy
  4. Click Deploy (again)
  5. Wait until you see the message Your application has been deployed
  6. Click on View CloudFormation Stack
  7. Under Outputs you will find the URL for the application (WebsiteURL)

From source code

Requires AWS CLI

sam build

sam deploy

Local Testing

Install AWS Sam in version > 1.3.2

sam build

sam local invoke

Deploying to AWS Serverless Application Repository

See contents of sar folder. Especially the README.md.

Cheat-Sheet

The full walkthrough of the lessons (under development) can be found in the LESSONS.md file

The following security issues exist in the application: ​

  • Event-data injection, leading to OS command injection (SAS-01)
    • Users can invoke the API with a document_url parameter value containing Linux OS commands. E.g. ; ls -LF
  • Improper exception handling and verbose error messages (SAS-10), leading to sensitive information disclosure
    • For example, invoking the API without the required parameter will return a verbose stack trace/exception
  • Insecure Serverless Deployment Configuration (SAS-03)
    • Publicly open S3 bucket (its name can be discovered from the subdomain/prefix of the URL)
    • The parameter document_url is not defined as a 'required' parameter in API gateway and can be ommitted
  • Over-privileged function permissions & roles, leading to data leakage of information stored in a DynamoDB table (SAS-04)
    • The function has CRUD permissions on the Dynamo table, which can be abused for reading sensitive data, or manipulating data
    • The function has FullAccess policy on the S3 bucket, leading to data tampering and data leakage, etc.
  • Inadequate function monitoring and logging (SAS-05) - the application doesn't properly log application layer attacks and errors (can be demonstrated through CloudWatch/CloudTrail)
  • Insecure 3rd Party Dependencies (SAS-06) - can be detected by scanning the project with a SCA scanning tool.
  • Application layer Denial of Service (SAS-08), which can be easily demonstrated
    • An attacker may invoke the API recursively multiple times, essentially spawning enough instances to reach the function's reserved capacity limit (which is set to 5). For example: 
      https://i92uw6vw73.execute-api.us-east-1.amazonaws.com/Prod/api/convert?document_url=https%3A%2F%2Fi92uw6vw73.execute-api.us-east-1.amazonaws.com%2FProd%2Fapi%2Fconvert%3Fdocument_url...
  • An undisclosed critical issue, as a bonus!

Acknowledgements

ServerlessGoat was initially created and contributed to OWASP by Yuri Shapira & Ory Segal, PureSec. ServerlessGoat for Java was adopted by Manuel Benz and Johannes Spaeth, CodeShield