[SR-Users] dictionary attacks

[Daniel-Constantin Mierla]

probably omitted by mistake, but please keep the mailing list cc-ed.

On 10/24/10 3:38 PM, Sergey Okhapkin wrote:
> Note that I check return code of www_authorize to be -1 (invalid user) and
> block IP in this case only. Other error codes should not block the IP address.
This one remembered me that in 3.1 we merged the auth modules and we 
used the one coming from ser because it has better nonce protection and 
other enhancements than kamailio version.

That means the return codes have changed, the new ones are listed now at:
http://kamailio.org/docs/modules/stable/modules_k/auth_db.html#id2753068

Added also note in migration wiki page:
http://www.kamailio.org/dokuwiki/doku.php/install:3.0.x-to-3.1.0#modules_k_auth_db

Cheers,
Daniel

> On Sunday 24 October 2010, you wrote:
>> I watched live an attack on voipuser.org while running 3.1 before
>> release. It lasted 18 hours. I didn't want to ban it because was useful
>> for testing and see if it reveals any weak. In most of the cases it hit
>> pike module. I got some data and plan to make an article about it soon.
>>
>> Anyhow, as a result of that, default config for kamailio has a section
>> for detecting and banning such "bad" IPs, using pike to detect floods
>> and htable to keep it blocked. Search WITH_ANTIFLOOD directive. It can
>> be enhanced like you pointed here, so if the authorize fails, add the IP
>> in the banned list stored in htable.
>>
>> Using fail2ban together with IP tables has the advantage of dropping the
>> packets before getting to application and eating cpu, although in the
>> case of voipuser.org the cpu was not affected much - the rate was
>> 170-200 requests per second.
>>
>> Cheers,
>> Daniel
>>
>> On 10/24/10 3:06 PM, Sergey Okhapkin wrote:
>>> I'm second for fail2ban. I block IP addresses with failed registration
>>> attempts for 1 hour. Here is my setup:
>>>
>>> kamailio.cfg:
>>>
>>> if (is_method("REGISTER")) {
>>>           if(www_authorize("", "subscriber")<   0) {
>>>                 if($rc == -1) {
>>>                        xlog("L_INFO","Invalid username from
>>> $proto:$si:$sp\n"); sl_send_reply("200","OK");
>>>                  } else
>>>                        www_challenge("", "0");
>>>                  exit;
>>>            }
>>> ....
>>>
>>> /etc/fail2ban/filter.d/openser.conf:
>>>
>>> [Definition]
>>> #_daemon = kamailio
>>> failregex = Invalid username from ...:<HOST>:
>>>
>>> /etc/fail2ban/jail.conf:
>>>
>>> findtime  = 600
>>>
>>> [openser-iptables]
>>> enabled  = true
>>> filter   = openser
>>> action   = iptables-allports[name=OPENSER, protocol=all]
>>> logpath  = /var/log/openser/openser # Replace with your sr log location
>>> maxretry = 10
>>> bantime = 3600
>>>
>>> On Sunday 24 October 2010, Uriel Rozenbaum wrote:
>>>> Juha,
>>>>
>>>> I think we should be specially careful about black-lists. We receive
>>>> many of these attacks in a per-day basis and a lot of them are from
>>>> residential addresses or university, so I'm guessing some kind of worm
>>>> or trojan performing the attack from various IPs.
>>>>
>>>> If you have the time, try fail2ban deamon. It can relate some
>>>> brute-force events and act accordingly blocking an IP on iptables,
>>>> executing a script. You send to "jail" those addresses for a period of
>>>> time, then you can get them out again; and of course you can manually
>>>> revert.
>>>>
>>>> Last, as a description of the attacks I saw, first it runs an NMAP
>>>> like scan checking which IPs answer from 5060, then it starts sending
>>>> registers (usually asterisk answers 404 if the user does not exist),
>>>> then when the proxy challenges, it interprets the user is found and
>>>> starts making dictionary attacks on the password (1234, admin, and so
>>>> on). Keep safe complicated passwords, make kamailio challenge
>>>> everything and you'll be safe. and again, fail2ban is a pretty good
>>>> solution for brute force.
>>>>
>>>> This might help you finding a solution for your attacks.
>>>>
>>>> Cheers,
>>>> Uriel
>>>>
>>>> On Sun, Oct 24, 2010 at 8:54 AM, Juha Heinanen<jh at tutpro.com>   wrote:
>>>>> while doing some tests, i noticed that one of my proxies started to
>>>>> receive lots of register requests with different user names starting
>>>>> from a letter.  there was also invite attempts in the logs.  they came
>>>>> from ip 202.82.16.99 which according to traceroute is somewhere in
>>>>> china.
>>>>>
>>>>> should we start publishing a black list of these attack ip addresses?
>>>>>
>>>>> -- juha
>>>>>
>>>>> _______________________________________________
>>>>> SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list
>>>>> sr-users at lists.sip-router.org
>>>>> http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users
>>>> _______________________________________________
>>>> SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list
>>>> sr-users at lists.sip-router.org
>>>> http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users
>>> _______________________________________________
>>> SIP Express Router (SER) and Kamailio (OpenSER) - sr-users mailing list
>>> sr-users at lists.sip-router.org
>>> http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users

-- 
Daniel-Constantin Mierla
http://www.asipto.com