What changed? A web‑application SSRF flaw was used to call the EC2 Instance Metadata Service version 1 (IMDSv1) on an instance running with the webdev IAM role, allowing an attacker to retrieve temporary credentials and then abuse Amazon Bedrock from a different AWS Region. Why it matters is that the same short‑lived credentials can be leveraged to bypass regional monitoring, perform unauthorized Bedrock API calls, and expose gaps in IAM, MFA, and metadata service configurations that affect AI, platform, and DevOps teams.
Attack Flow Overview
The guide breaks the incident into five sequential steps:
- Initial access: SSRF in a web app hosted on an EC2 instance sends a request to the local IMDSv1 endpoint.
- Credential harvesting: IMDSv1 returns the temporary access key, secret key, and session token for the
webdevrole without requiring a session token in the request. - Permission testing: The harvested credentials are used to issue IAM operations, which generate failure alerts in the
us-east-1Region. - Service pivoting: When IAM actions are denied, the attacker switches to Amazon Bedrock, a service the role can reach.
- Region hopping: Bedrock API calls are issued from
us-east-2, creating a cross‑Region footprint that evades region‑specific alerts.
CloudTrail Signals to Watch
CloudTrail logs captured the following observable events:
- Failed IAM API calls originating in
us-east-1. - Successful console sign‑ins without multi‑factor authentication (MFA).
- Unexpected Amazon Bedrock API activity recorded in
us-east-2.
Each of these entries maps to one or more stages of the attack, providing a timeline that can be reconstructed from the trail.
Mitigation and Hardening Steps
Practitioners can address the identified gaps without altering application logic:
- Enforce IMDSv2: Require the newer metadata service that mandates a session token, eliminating the SSRF‑to‑credential path.
- Scope IAM role permissions: Review the
webdevrole policy to ensure it only grants the minimum actions needed for the application. - Enable MFA for console access: Require MFA for all privileged sign‑ins to reduce the impact of credential leakage.
- Cross‑Region monitoring: Correlate CloudTrail events across Regions to detect sudden service usage shifts, especially for AI services like Bedrock.
- Alert on failed IAM calls: Treat repeated IAM denials as potential reconnaissance and trigger investigation workflows.
Related CloudNinjas coverage: AWS.
What This Means For Practitioners
SSRF combined with IMDSv1 creates a direct path from a vulnerable web front‑end to cloud‑wide credentials. Teams responsible for AI workloads, platform services, or DevOps pipelines should verify that all EC2 instances run IMDSv2, audit role scopes, and tighten console authentication. Additionally, extend logging and alerting to span multiple Regions so that a pivot to services such as Amazon Bedrock cannot hide behind geographic boundaries.