Hey everyone,
Another trend we see in this hacking activity:
The hackers seems to be collecting SIP accounts hacked for a few weeks
from one server and then from a different IP address/Asterisk server
they start using the hacked accounts earlier to make their fraudulent
calls. There could be weeks between the time they discover your weak SIP
account and the time they start using it.
Did you know that if someone gets hurt and that same person can prove
the calls are being made by your phone system, the administrator of your
phone system can be sued for being negligent to properly secure their
systems and are personally responsible for any damages cause by this action!
Very scary!
Another easy way to reduce your system from being hacked is to design a
mouse trap: create an extension 200 with password 1234. Then you program
a separate context for extension 200 with no possibilities to make any
calls. Most hackers stop sniffing for passwords after successfully
guessing the first account. Then design a small tool to gather IP
addresses that uses extension 200 and block all access from those IP
addresses.
Cheers.
Stephan Monette
Unlimitel Inc.
Tel.: 613-688-6212. x221
TF : 1-877-464-6638, x221
FAX : 613-482-1077
Chuck Mariotti wrote:
I also made some recommendations to Unlimitel, but maybe this should be shared
with providers as to what would have allowed me to catch this issue:
I know this is likely a lot of work, but... it would be nice to have the daily
totals in the body of the email and subject. I rarely open my email attachment
to see the minutes used for a day, but if there was a dollar amount or # of
minutes in the subject, it would make it easier to scan with the eyeball. I
would have missed our recent hack completely if I didn't get returned calls
complaining... which made me check my CDR in Asterisk, which made me look the
next day in your report. It also happened on a Friday night (I'm sure on
purpose) so I wouldn't have even attempted to look until Monday.
I know that's a lot more horsepower needed than just attaching a text file. But
I know it would be helpful to me.
As well, could be useful to set an alert on DID for minutes used in a day... I
think that's asking too much though.
Regards,
Chuck
-----Original Message-----
From: Chuck Mariotti [mailto:[EMAIL PROTECTED]
Sent: Tuesday, November 11, 2008 6:40 PM
To: Simon P. Ditner; [email protected]
Subject: RE: [on-asterisk] SIP hack attempts
Simon, I ran into and was a victim of such an attack back in mid-august. I
emailed unlimitel and this is the recommendations that Stephen had:
Dear Customer,
We're seeing a lot more hacking activities lately and here's a short list to do
on your server to help keep it secure:
1- Change all your default passwords on the server (root, admin, maint). Never
use easy to remember passwords like 1234,...
2- Never use passwords like 1234 for your any extensions on your server.
There's a lot of hackers out there just scanning your Asterisk server to detect
extensions (200 to 299 mostly) with easy passwords like 1234.
3- Block access to your server and just leave the RTP, SIP and IAX2 opened.
Just leave the SSH and WEB access opened to your static IP from the office. You
can do this by using the iptables from Linux on your Asterisk server.
4- Monitor your network and if you see some activities scanning your server,
keep note of the source IP address and block it completely from your server.
Hope this few tips can help you keep your server more secure and avoid big
telephone bills.
Stephan Monette
Unlimitel Inc.
-----Original Message-----
From: Simon P. Ditner [mailto:[EMAIL PROTECTED]
Sent: Tuesday, November 11, 2008 6:00 PM
To: [email protected]
Subject: Re: [on-asterisk] SIP hack attempts
Not a single reply?
It's very easy to disregard this message, but I think this is something
VERY IMPORTANT that we should be talking about much more -- especially
for those deploying systems for remote workers over a public network.
There is a huge opportunity for toll fraud, voip spam, and such as this
market segment continues to grow.
Lability becomes an issue too -- who's responsible when someone is
defrauded via your phone system? The phone companies have a record of you
calling so-and-so; can you prove you didn't?
These are the sort of scans I've been spotting hitting some of my systems
the past week, trying to brute force. You'll see incremental scans like:
[Nov 5 19:58:30] NOTICE[19408] chan_sip.c: Registration from '"0"<sip:[EMAIL
PROTECTED]>' failed for 'EE.FF.GG.HH' - No matching peer found
...
[Nov 5 20:20:21] NOTICE[19408] chan_sip.c: Registration from '"1000"<sip:[EMAIL
PROTECTED]>' failed for 'EE.FF.GG.HH' - Wrong password
...
We were discussing this around the office, particularly how sipvicious
(http://sipvicious.org) works, and it was noted that you can find active
SIP accounts easily, and then start a brute force against a known active
account.
I poked my head into #asterisk-dev, and asked if there were a feature in
the works to automatically disable accounts after a number of bad auth
attempts. It's been discussed, but so far no code.
There are however some easy things you can do that are common across
running any service on the internet.
Inside of asterisk, you can cut down on your exposure by only allowing
particular SIP accounts to be registered from remotely by putting
deny-based ACL's on the other accounts, listing your local subnets as
permissable:
sip.conf
[somepeer]
type=peer
deny=0.0.0.0/0.0.0.0
permit=192.168.0.0/255.255.255.0
You can also create automatic blacklisting of IP addresses that attempt
too many SIP authentications per interval, such as this SSH example:
http://www.mattiasholm.com/node/6
Thoughts? What are other people doing to protect their exposure?
re,
spd
On Mon, 10 Nov 2008, Andre Courchesne - Consultant wrote:
Hi,
Just to let you know that I see a proliferation is SIP hack attempts. Twice
today I happened to be logged in servers where I saw SIP discovery from IP
212.12.148.109 and on the other server that same IP had actually gained
controlled of a SIP account (which was created with a weak secret by the
administrator).
The call pattern indicated that calls were made by a dialer of some sort
and the SIP packets were originating from an Asterisk server.
So be carefull about your server that you have to let unprotected on an
internet segment.
Andre
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