[ale] SIP attack

[Paul Cartwright]

justg read this on a fedora list, if anyone runs a VOIP server:

This is off topic, but I thought I should tell people.

This past weekend, I suffered a DOS attack launched against VOIP SIP
Clients.  The attack came, at different times, from 3 separate IP addresses.

I blocked the IP addresses using IP Tables when I discovered it.

The attack was a bombardment of several hundred SIP REGISTER requests,
per second, with a user agent of friendly-scanner.
The attack was a sustained attack over three days.

I contacted my ISP.  They told me they have taken steps.

I contacted 2 of the 3 owners of the offending IP addresses.
The third owner of the IP address was a job site address in China,
and I couldn't figure out how to contact them.

In my case, I run the VOIP SIP program, twinkle.

Twinkle started consuming vast amounts of memory, going from a normal 5
MiB usage to 500-600 MiB usage, before I realized what was happening.

Twinkle attempted to respond to each incoming packet with an outgoing
SIP error packet.

I posted a message on the yahoo group used by twinkle asking what they
could do to better handle such an attack.

If you suddenly seem to have memory problems, I suggest running
something like System Monitor to find out what applications have memory.

I also be on the lookout for unexpectedly high internet traffic.

This message is off-topic, because it is not specific to Fedora.
I thought it wouldn't hurt to let people know of this type of attack.
I hope people don't object to this off-topic post.
-- 
Paul Cartwright
Registered Linux user # 367800
Registered Ubuntu User #12459
http://usdebtclock.org/