Office365userenum

Vulnerable Application

External python module compatible with v2 and v3.

Enumerate valid usernames (email addresses) from Office 365 using ActiveSync. Differences in the HTTP Response code and HTTP Headers can be used to differentiate between:

• Valid Username (Response code 401)
• Valid Username and Password without 2FA (Response Code 200)
• Valid Username and Password with 2FA (Response Code 403)
• Invalid Username (Response code 404 with Header X-CasErrorCode: UserNotFound)

Note this behaviour appears to be limited to Office365, MS Exchange does not appear to be affected.

Microsoft Security Response Center stated on 2017-06-28 that this issue does not "meet the bar for security servicing". As such it is not expected to be fixed any time soon.

This script is maintaining the ability to run independently of MSF.

Office365's implementation of ActiveSync is vulnerable.

Verification Steps

1. Create a file containing candidate usernames (aka email addresses), one per line.
2. Do: use auxiliary/gather/office365userenum
3. Do: set users [USER_FILE] with the file you created.
4. Do: run
5. Valid and Invalid usernames will be printed out to the screen.

Options

LOGFILE

Output file to use for verbose logging.

OUTPUT

Output file for results.

PASSWORD

Password to use during enumeration. Note this must exist but does not necessarily need to be valid. If it is found to be valid for an account it will be reported.

THREADS

Number of concurrent requests to use during enumeration.

TIMEOUT

HTTP request timeout to use during enumeration.

URL

URL of Office365 ActiveSync service.

USERS

Input fie containing candidate usernames, one per line.

VERBOSE

Enable/Disable DEBUG logging

Scenarios

The following demonstrates basic usage, using the supplied users wordlist and default options.

msf auxiliary(gather/office365userenum) > set users /home/msfdev/users
users => /home/msfdev/users
msf auxiliary(gather/office365userenum) > run

[*] 

.       .1111...          | Title: office365userenum.py
    .10000000000011.   .. | Author: Oliver Morton (Sec-1 Ltd)
 .00              000...  | Email: [email protected]
1                  01..   | Description:
                    ..    | Enumerate valid usernames from Office 365 using
                   ..     | ActiveSync.
GrimHacker        ..      | Requires: Python 2.7 or 3.6, python-requests
                 ..       |
grimhacker.com  ..        |
@grimhacker    ..         |
----------------------------------------------------------------------------
    This program comes with ABSOLUTELY NO WARRANTY.
    This is free software, and you are welcome to redistribute it
    under certain conditions. See GPLv2 License.
----------------------------------------------------------------------------

[+] 401 VALID_USER [email protected]:Password1
[-] 404 INVALID_USER [email protected]:Password1
[*] Scanned 1 of 1 hosts (100% complete)
[*] Auxiliary module execution completed