module

Office 365 User Enumeration

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Disclosed
Sep 5, 2018
Created
Sep 9, 2021

Description

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.

Author

Oliver Morton (GrimHacker) [email protected]

References

Module Options

To display the available options, load the module within the Metasploit console and run the commands 'show options' or 'show advanced':


    msf > use auxiliary/gather/office365userenum
    msf auxiliary(office365userenum) > show actions
        ...actions...
    msf auxiliary(office365userenum) > set ACTION < action-name >
    msf auxiliary(office365userenum) > show options
        ...show and set options...
    msf auxiliary(office365userenum) > run
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