Breaching AWS Through Shadow Resources

Hidden Dependencies in AWS Services

The cloud seems complex, but it's what happens behind the scenes that really complicates things. Some services utilize others as resources as part of their logic/operation. Interestingly enough, it turns out that this could lead to catastrophic results if done unsafely.

Six Shadow Resource Vulnerabilities

This talk will present six critical vulnerabilities that we found in AWS, along with the stories and methodologies behind them. These vulnerabilities, which were all promptly acknowledged and fixed by AWS, could allow external attackers to breach almost any AWS account. The vulnerabilities range from remote code execution, which could lead to full account takeover, to information disclosure, potentially exposing sensitive data, or causing denial of service. The session will share our story of discovery, how we were able to identify commonalities among them, and how we developed a method to uncover more vulnerabilities and enhance the impact by using common techniques leading to privilege escalation. We will then detail our approach for mapping service external resources and release our Open-Source tool to research service internal API calls. We will also present a method to check if accounts have been vulnerable to this vector in the past.

Cross Tenant Exploitation and Defense

We will conclude our talk with the lessons learned during this research and our future line of research. We will highlight new areas that cloud researchers need to explore when hunting for cloud vulnerabilities and highlight best practices for developers to use in complex environments.