[Koha] F5 Attacks

Thu Oct 27 01:52:49 NZDT 2016

I disagree.  If Koha is offered out of the box, and we take time to fix 
security issues, then it's normal for users to expect "basic" attacks to 
be taken care of.

More so, blocking IP is not a possibility if genuine users are involved 
using a station from within the library.

I'm not saying you're wrong that it's mostly sysadmin work and not Koha, 
but it doesn't mean nothing can be done.  From the apache's threads, I 
found nothing useful (mostly derisive comments).  But we could at least 
talk about it.

What about having a javascript preventing refresh on the page withing 5 
sec of each other?  Needs to be done in a way that the refresh doesn't 
restart the timer.

What about having the OPAC search be code where the refresh will 
basically send nothing ?  The checkbox are filled, the request is sent 
to the backend, but the frontend keeps nothing...  I'm just smoking 
here, but I'm trying to induce some brainstorming in this interesting topic.

Philippe Blouin,
Responsable du développement informatique

Tél.  : (888) 604-2627
philippe.blouin at inLibro.com <mailto:philippe.blouin at inLibro.com>

inLibro | pour esprit libre | www.inLibro.com <http://www.inLibro.com>
On 10/26/2016 07:13 AM, Jonathan Druart wrote:
> Hi,
> I don't think this can/must be fixed on Koha side.
> It's a sysadmin duty to take care of that.
> I would take a look at fail2ban to parse the web server access logs. But
> make sure not to block your X librarians using the same ip ;)
>
> On Wed, 26 Oct 2016 at 12:28 Pedro Amorim <pjamorim91 at gmail.com> wrote:
>
>> I have tested this and the stress caused on the server is very severe. It
>> seems that for every request, a new zebra process is created and the server
>> will only respond when the last one is finished. This ofc will result in
>> time outs and eventually a crash in the server.
>>
>> This is a major critical issue IMO, anyone who knows about this has the
>> power to deny the service of any Koha online without using any additional
>> hacking/attacking software.
>>
>> The Koha I'm working on right now - still in development - is accessed
>> behind a proxy server, and I will attempt to solve the problem through
>> that, by limiting the requests from the same origin with very little time
>> between them. Still, even if I'm successful with this, the problem will
>> still lie in Koha.
>>
>> Anyone with some sort of insight is very welcome.
>>
>> Pedro Amorim
>>
>> 2016-10-26 8:24 GMT+00:00 clint.deckard <clint.deckard at frontiers.co.nz>:
>>
>>> I have had this issue appear today. I have attempted to set up
>> mod_evasive
>>> for apache but it doesn't seem to have solved the problem.
>>> I would really appreciate some advice.
>>> Clint.
>>>
>>>
>>> rfblanchard wrote:
>>>
>>>> Assume a basic opac search:
>>>> http://..../cgi-bin/koha/opac-search.pl?q=dog&branch_group_l
>>>> imit=branch%3A349
>>>>
>>>> This would take about 10 seconds to return the first time.
>>>>
>>>> Assume the user refreshes the results using f5 and keep there finger
>>>> there a
>>>> moment to long (3s):
>>>> This would kill my server for about 1 minute.
>>>>
>>>> Any attacker could easily make the server unresponsive indefinitely by
>>>> simply holding f5 on an opac search.
>>>>
>>>> Any recommendations on how to deal with this problem?
>>>>
>>>> here is a sample from top:
>>>>
>>>> Tasks: 313 total,   3 running, 309 sleeping,   0 stopped,   1 zombie
>>>> %Cpu(s): 93.7 us,  5.2 sy,  0.0 ni,  1.0 id,  0.2 wa,  0.0 hi,  0.0 si,
>>>> 0.0
>>>> st
>>>> KiB Mem:  16465036 total,  1532492 used, 14932544 free,    63180 buffers
>>>> KiB Swap:  8526844 total,        0 used,  8526844 free.   505124 cached
>>>> Mem
>>>>
>>>>    PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+
>>>> COMMAND
>>>>   7027 peischo+  20   0  416164 162924  12756 S  58.8  1.0   0:26.43
>>>> /usr/share/koha
>>>>   7009 peischo+  20   0  416800 163524  12756 S  56.5  1.0   0:33.77
>>>> /usr/share/koha
>>>>   7444 peischo+  20   0  129832  15216   5900 R  37.2  0.1   0:01.12
>>>> zebrasrv
>>>>   7445 peischo+  20   0  129832  15216   5900 R  35.6  0.1   0:01.07
>>>> zebrasrv
>>>>   1151 mysql     20   0  886564 181096  10808 S   8.6  1.1   1:27.57
>> mysqld
>>>>   7435 koha      20   0   25892   3272   2528 R   0.3  0.0   0:00.03 top
>>>>      1 root      20   0  176144   5044   3096 S   0.0  0.0   0:01.43
>>>> systemd
>>>>      2 root      20   0       0      0      0 S   0.0  0.0   0:00.00
>>>> kthreadd
>>>>
>>>>
>>>>
>>>> --
>>>> View this message in context: http://koha.1045719.n5.nabble.
>>>> com/F5-Attacks-tp5906098.html
>>>> Sent from the Koha-general mailing list archive at Nabble.com.
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