[Freeipa-users] Restrict AD users from passwd

[Petr Spacek]

On 14.8.2013 15:48, Brian Lee wrote:
> Hi Sumit,
>
> Thanks for the suggestion. I'll have to give this some thought, since we
> have 100+ AD servers, this might not be well received by the AD team. If
> anyone can think of a better mousetrap than this, let me know.
>
> Thanks,
> Brian
>
>
>
>
> On Wed, Aug 14, 2013 at 9:37 AM, Sumit Bose <sbose at redhat.com> wrote:
>
>> On Wed, Aug 14, 2013 at 09:19:17AM -0400, Brian Lee wrote:
>>> Hi All,
>>>
>>> Our current account management policy requires that users change their AD
>>> passwords via a special portal, however I've noticed that this can be
>>> bypassed by issuing passwd on a Linux system while logged in with AD
>>> credentials, thus changing their AD password.
>>>
>>> Any thoughts on the best way to prevent this action?
>>>
>>> What I've considered so far is removing the trust in AD, effectively
>>> creating a one-way trust, but that would limit functionality for future
>>> interoperability.
>>>
>>> Additionally, we could change the permissions for passwd on each Linux
>>> system, but this would be somewhat hackish and also complicated to
>> enforce,
>>> since we're waiting on Foreman + Puppet to properly be integrated into
>>> Katello for our configuration management solution.
>>>
>>> Any way to restrict this via the FreeIPA UI?
>>
>> I think the only safe way to achieve this is to block port 464 on the AD
>> servers for the Linux hosts. Because basically what passwd is doing here
>> via SSSD is to change the Kerberos password. The same can be done with
>> the kpasswd command, it does not require any privileges the user only
>> needs to know his current password. So even if we add an option to force
>> SSSD to reject password changes for users from trusted domains there are
>> other ways for users to change the password which cannot be controlled
>> by IPA.
>>
>> Please note that changing the AD password with kpasswd would even work
>> without trust.

IMHO the correct approach is to enforce password policy on AD side, otherwise 
users can use standard Kerberos protocol and do the change anyway (i.e. 
effectively bypass IPA and your portal completely).

AFAIK AD has some checkbox which determines if the user is allowed to change 
own password or not.

The next question is how 'the portal' does the password change and if it will 
continue to work if you disallow users to change own password on AD side.

-- 
Petr^2 Spacek