Derp | Security Research

SSRF Exploitation of EC2 IMDSv1 Credentials Led to Unauthorized Amazon Bedrock Use

AWS documented an incident-response scenario in which an attacker exploited a server-side request forgery (SSRF) flaw in an EC2-hosted web application to retrieve temporary credentials for the instance's attached webdev IAM role through IMDSv1. The attacker enumerated the role's permissions, established an AWS Management Console session without MFA, pivoted from us-east-1 to us-east-2, and enumerated Amazon Bedrock foundation models. The actor then invoked Amazon Nova Pro through the Converse API, resulting in unauthorized token consumption. The activity was enabled by IMDSv1 exposure, an overprivileged EC2 role with unnecessary cross-Region Bedrock permissions, and missing MFA, with inconsistent regional logging and controls potentially limiting detection. AWS advises remediating the SSRF flaw, requiring IMDSv2 for EC2 metadata access, revoking and investigating use of the compromised role, reviewing CloudTrail across all Regions, restricting Bedrock permissions, and enabling Bedrock model-invocation logging to determine whether prompts or generated outputs were exposed.