Re: [Nagios-devel] Security issue

[Arno L. <al...@it...>]

Hi,

07.11.2008 09:33, Andreas Ericsson wrote:
> Arno Lehmann wrote:
>> Hi,
>>
>> 06.11.2008 12:45, Andreas Ericsson wrote:
>> ...
>>> A couple of things to note:
>>> * Information disclosure is not possible. No remote user can see
>>>   anything from your authentication-protected Nagios servers.
>> I'm not sure this is correct... see what all the web 2.0 stuff is 
>> about - javascript executes http queries, captures the output, and 
>> does something with it.
>>
> 
> No. Javascript and flash are

Let me add one word here: "theoretically".

There have been many security issues in browsers already, and it's 
probably not unlikely there will be more.

Of course, that's not exactly Nagios' problem. Still, if the Nagios 
CGIs can be improved to make such an exploit less likely, the required 
work will be well invested.

> protected by the same-site policy
> (according to Tim Starling of the wikimedia foundation, who brought
> this to some nagios-developer's attention), so they can't be made
> to send stuff from nagios-server.example.com to evilsite.com.
> 
>> I guess it's possible for a javascript in Dr. Evils pages to get the 
>> cgi output without actually displaying it, and to forward the 
>> information collected to Dr. Evils web server.
> 
> Yes, but only from CGI's running on evilsite.com. Otherwise javascript
> kiddies would be billionaires from ripping people off through online
> banking or whatever.

They do, don't they?

Or, at least, they try, and only the ones who are well beyond the 
kiddie stage are successful - but still the problem exists.

>> Don't ask for a sample exploit, please.
>>
> 
> Well, if you can think one up, you'll have discovered a fundamental
> problem in how javascript works (it will be browser-dependant) and
> should definitely report it to the developers of that browser.

Sure... unfortunately, discovering such things is well beyond my 
capabilities.

>>> * Invalid commands read from the FIFO are always dropped flat by
>>>   Nagios.
>>> * Since commands must be valid, it's not very easy to submit a
>>>   command that has all the information required. Social engineering
>>>   is required.
>>> * You *will* notice if this happens to you, since you all of a
>>>   sudden will end up with cmd.cgi (not in a frame either) saying
>>>   "Command submitted successfully" or some such.
>> See above - AJAXified web pages probably can prevent this.
>>
> 
> Nopes. You see above ;-)

Nopes^2 - it's probably possible ;-)

But, just to prevent this discussion from going on eternally - the 
current fixes seem to be an important step towards a more secure web 
interface, and try if you might, there's no cure against browser 
defects possible inside Nagios' cgis - I'm aware of that.

Arno

-- 
Arno Lehmann
IT-Service Lehmann
Sandstr. 6, 49080 Osnabrück
www.its-lehmann.de