Context

I was onboarding a junior dev and we were pair-programming with Claude 3. We asked for help setting up async AWS S3 uploads in Python.

Claude suggested pip install python-aws-async-utils with beautifully documented example code.

The Attack

The package installed fine. The code worked perfectly in local testing. We merged it into our data pipeline.

At 3am I got a CloudWatch alert: 847 EC2 instances had been launched in 14 regions. Our AWS bill in 6 hours: $34,247.

The package had read ~/.aws/credentials and os.environ on import and sent everything to a server in Moldova.

Because Claude generated working example code, we trusted it completely. The package did what it claimed. It just also did a lot more.

AWS waived most of the bill after we filed a security incident report. But we spent a week auditing every system the credentials had touched.

Total time lost: ~300 developer hours.