[asterisk-users] Hack attempt sequential config file read looking for valid files.

[Victor Villarreal]

Hi, Jerry,

I don't know what S.O. you have in the Server, but you can check the man
page (https://linux.die.net/man/8/in.tftpd) for tftpd and use the options
--address, so you can tell tftp from what interface/port this service
listen request.

>From the IP in your logs (69.64.57.18) the request came from a web hosting
provider (http://www.heg.com/). So, the request came from Internet, so your
server listen TFTP request from outside, what is bad.

You can use iptables in any Linux distro to block incoming TFTP traffic.
TFTP is a UDP protocol at port 69.

Example:

/sbin/iptables -A INPUT -i eth0 -p udp --destination-port 69 -j DROP

Change eth0 to the correct name of your public internet server interface.



2017-04-21 13:27 GMT-03:00 Jerry Geis <jerry.geis at gmail.com>:

> I "justed" happened to look at /var/log/messages...
>
> I saw:
> Apr 21 12:18:40 in.tftpd[22719]: RRQ from 69.64.57.18 filename
> 0004f2034f6b.cfg
> Apr 21 12:18:40 in.tftpd[22719]: Client 69.64.57.18 File not found
> 0004f2034f6b.cfg
> Apr 21 12:18:40 in.tftpd[22720]: RRQ from 69.64.57.18 filename
> 0004f2034f6c.cfg
> Apr 21 12:18:40 in.tftpd[22720]: Client 69.64.57.18 File not found
> 0004f2034f6c.cfg
> Apr 21 12:18:40 in.tftpd[22721]: RRQ from 69.64.57.18 filename
> 0004f2034f6d.cfg
> Apr 21 12:18:40 in.tftpd[22721]: Client 69.64.57.18 File not found
> 0004f2034f6d.cfg
> Apr 21 12:18:40 in.tftpd[22722]: RRQ from 69.64.57.18 filename
> 0004f2034f6e.cfg
>
> so basically an sequential read of polycom MAC address config files.
> Some is trying to read to determine if I have any polycom files just
> sequential read after read.
> And if so - it would get any extension and password at that time.
> Luckily I have none.
>
> However - how does one block attempts like this ?
>
> Thanks!
>
> Jerry
>
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