Thread by @jhencinski

Highlights from chasing an attacker in #AWS this week:

Initial lead: custom alert using #CloudTrail
- SSH keygen from weird source
IP enrichment helped
Historical context for IAM user, "this isn't normal"
#GuardDuty was not initial lead
- Did have LOW sev high vol alerts

Attacker tradecraft:
- Made ingress rules on sec groups that allowed any access to anything in VPC
- Interesting API calls: > 300 AuthorizeSecurityGroupIngress calls
- Spun up new ec2 instance likely to persist
- Mostly recon - "What policy permissions does this IAM user have?"

Investigations:
Orchestration was super helpful. We bring our own.

For any AWS alert we auto acquire:
- Interesting API calls (anything that isn't Get*, List*, Describe*)
- List of assumed roles (+ failures)
- AWS services touched user user/role
- Gave us answers, fast

#VPC and #CloudTrail logs to chase new leads

Key Takeaways:
- Good to bring custom detections to bear in #AWS
- IP enrichment helps
- Contextual info aka "decision support" is how you win
- Just like on-prem security, knowing what's normal vs what's not is also how you win