What is the Python script ‘main_entrance_cross_account.py’ doing in EC2?

Honestly, the name sounds suspicious—like 'oh_crap_i_got_powned.py'. It could be a script that allows unauthorized access across all your accounts. You definitely want to investigate this further.

'main_entrance_cross_account.py' isn’t a standard AWS file. You really should check the contents of that script. It might give you clues about its purpose.

If you're part of a larger organization, check if they run any hardening scripts. It’s good to look at your CloudFormation stacks too. This could be a sign of something malicious, so make sure to review your roles, users, and any misconfigured services that might be overly trusting.

It sounds like that script might not be an official AWS one. Are you working for a company that creates its own Amazon Machine Images (AMIs)? It's possible it came from a security vendor or maybe something custom your employer developed. If you could share part of the script, that might help us give you more insight.