Security Researchers Reveal AWS IAM Containment Bypass and Propose SCP-Based Fix
Key Takeaways
- ▸AWS IAM's ~4-second eventual consistency window allows attackers to remove containment policies during incident response, bypassing standard identity-level isolation techniques
- ▸Current AWS incident response playbooks, including AWS's official Credential Cleanup Procedure, are vulnerable to this race condition attack
- ▸Researchers propose using Service Control Policies (SCPs) to enforce irremovable quarantine policies, providing attacker-resistant identity-level containment without requiring full account isolation
Summary
Security researchers at Sysdig have identified a critical vulnerability in AWS incident response procedures, demonstrating how attackers can exploit IAM's eventual consistency window to bypass standard containment measures. The research, published by Eduard Agavriloae, shows that during IAM's ~4-second propagation window, attackers can remove deny-all policies that defenders attach to compromised identities, rendering identity-level containment ineffective. This weakness affects both AWS's official incident response recommendations and industry-standard IR playbooks.
The researchers found that AWS's recently published Credential Cleanup Procedure, released following their responsible disclosure, still falls short against sophisticated attackers who understand IAM's eventual consistency behavior. While the official guidance includes steps to attach credential management deny policies and nullify active sessions, these measures can be circumvented during the consistency window when an attacker races to detach policies before they fully propagate.
To address this gap, the research team proposes an alternative containment strategy using AWS Service Control Policies (SCPs) that makes quarantine policies irremovable by anyone except designated incident response roles. This approach provides a middle ground between disruptive account-level isolation and vulnerable identity-level containment, allowing security teams to surgically lock down compromised principals without affecting entire AWS accounts. The SCP-enforced technique effectively closes the policy detachment vulnerability while maintaining the precision benefits of identity-level response.
- The vulnerability affects the choice between disruptive account-level isolation and more surgical identity-level containment during security incidents
