Step by step AWS Cloud Hacking

Transcript

1. Ekoparty 2020 Andrés Riancho
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6. need credentials • • • 6
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8. IAM permissions 8
9. 9 http://169.254.169.254/ /latest/meta-data/iam/security-credentials/ /latest/meta-data/iam/security-credentials/{role-name}
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11. 11 from urllib.request import urlopen from flask import request @app.route('/ssrf') def handler(): url = request.args.get('url') return urlopen(url).read()
12. Instance metadata and S3 compromise
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15. two ways to enumerate permissions IAM service In most cases this will fail brute-force 15
16. Get* / List* / Describe* DryRun parameter 16
17. 17 SUPPORTED_SERVICES = [ 'ec2', 's3' ]
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19. ./enumerate-iam.py
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21. many things the attacker doesn't know. 21 { "Statement":[ { "Effect":"Allow", "Action":[ "s3:*", "lambda:*", "..." ], "Resource":"*" } ] }
22. try to elevate privileges to a principal with full access 22 { "Statement":[ { "Effect":"Allow", "Action":[ "*", ], "Resource": "*" } ] }
23. Lambda function will have access to the IAM role 23
24. Getting * on *
26. existing trust policy in the AdminRole 26
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28. 28 { "Effect": "Allow", "Principal": { "AWS": "arn:aws:iam::925877178748:root" }, "Action": "sts:AssumeRole" } { "Effect": "Allow", "Principal": { "AWS": ["arn:aws:iam::925877178748:root", "arn:aws:iam::320222540496:root"] }, "Action": "sts:AssumeRole" }
29. Never trust the trust policy
30. 30 ARN for the backdoored role
32. 32 most resources in the AWS account VPC is completely isolated from the Internet
34. 34 VPN between the attacker's workstation and a VPC
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36. vpc-vpn-pivot
38. From zero to full pwn
40. 40 • enumerate-iam • pacu • vpc-vpn-pivot Follow @AndresRiancho