[CentOS] saslauthd attack

John Hinton webmaster at ew3d.com
Thu Feb 11 04:04:36 UTC 2010


I am running IPTraf and have one offender... not a problem to find the 
address by hand, but I know these things grow. Years ago it was ssh... 
they are still trying. Then FTP... then smtp... but I have not before 
seen one like this where I can't find it logged... and I want to put 
into place some automated scripts to deal with it immediately. As the 
kiddie scripts seem to go, with time, there is a need to kill off such 
things before you have 10,000 systems out there trying to authenticate 
once every second or two.

It is dictionary as it has changed to alias from anna now. LOL!!! They 
aren't going to get in... just wasting resources.

John

Clint Dilks wrote:
> Perhaps you can use netstat to identify who is currently connected to 
> the machine.  Then run it several times over a short period and block 
> the most likely culprits ?
>
>
> John Hinton wrote:
>   
>> Yes... most of them. Just the new PITA. Anyway... I still can't seem to 
>> figure out how to log the IP addresses for this attack.
>>
>> The system is saslauthd running as a service... sendmail and dovecot 
>> setup. I have log levels in sendmail set to 14. Something has to be able 
>> to log the offender(s).
>>
>> Any ideas what I'm missing or where to look?
>>
>> John
>>
>> Lincoln Zuljewic Silva wrote:
>>   
>>     
>>> I supose that you are using SMTP authentication with SASL.
>>>
>>> >From the log "service=smtp"...so, in fact, the attack is coming from
>>> the SMTP server and not directly to the SASL.
>>>
>>> I guess that someone is trying to do a brute force attack on the SMTP server.
>>>
>>> Regards
>>> Lincoln
>>>
>>> On Wed, Feb 10, 2010 at 6:08 PM, John Hinton <webmaster at ew3d.com> wrote:
>>>   
>>>     
>>>       
>>>> I'm seeing a lot of activity over the last two days with what looks to
>>>> be a kiddie script. Mostly trying to access several of our servers with
>>>> the username anna. All failed... in fact I don't think we have a user
>>>> anna on any of our servers. Meanwhile...
>>>>
>>>> I'm running Sendmail. This pertains to Centos 4 and 5 servers. I'm also
>>>> running fail2ban on some and Ossec on others. So far, no blocking is
>>>> being done. When I look at the logs all I find is under messages and
>>>> here is a sample:
>>>>
>>>> Feb 10 05:23:08 neptune saslauthd[3370]: do_auth         : auth failure:
>>>> [user=anna] [service=smtp] [realm=] [mech=shadow] [reason=Unknown]
>>>> Feb 10 05:23:25 neptune saslauthd[3369]: do_auth         : auth failure:
>>>> [user=anna] [service=smtp] [realm=] [mech=shadow] [reason=Unknown]
>>>> Feb 10 05:23:58 neptune saslauthd[3370]: do_auth         : auth failure:
>>>> [user=anna] [service=smtp] [realm=] [mech=shadow] [reason=Unknown]
>>>> Feb 10 06:56:53 neptune saslauthd[3370]: do_auth         : auth failure:
>>>> [user=anna] [service=smtp] [realm=] [mech=shadow] [reason=Unknown]
>>>> Feb 10 06:56:54 neptune saslauthd[3368]: do_auth         : auth failure:
>>>> [user=anna] [service=smtp] [realm=] [mech=shadow] [reason=Unknown]
>>>> Feb 10 06:56:55 neptune saslauthd[3370]: do_auth         : auth failure:
>>>> [user=anna] [service=smtp] [realm=] [mech=shadow] [reason=Unknown]
>>>> Feb 10 06:56:59 neptune saslauthd[3368]: do_auth         : auth failure:
>>>> [user=anna] [service=smtp] [realm=] [mech=shadow] [reason=Unknown]
>>>>
>>>> So, I can't write a rule to block this attack as I can't find any IP
>>>> address to block. I've looked and googled til my eyes are red and can't
>>>> find where to set logging in saslauthd or where ever it needs to be set
>>>> to record the IP address generating these failures. Does anyone have an
>>>> idea?
>>>>
>>>> Also, some may wish to do a grep 'do_auth' on messages to see if this is
>>>> happening to you. They sometimes come in rapid succession.
>>>>
>>>> John Hinton
>>>> _______________________________________________
>>>> CentOS mailing list
>>>> CentOS at centos.org
>>>> http://lists.centos.org/mailman/listinfo/centos
>>>>
>>>>     
>>>>       
>>>>         
>>>   
>>>     
>>>       
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