RE: Port 445 increase? [UPDATE]

["Mike Hrubes" <MHrubes () wizmo com>]

Thanks for the replies from everyone.  The scan/attack has stopped as of yesterday evening.  I guess what I found 
interesting was the pattern it followed.  To me, it almost looked like a DOS because of the source IPs and the format 
it followed.  I discarded the idea of a scan as it wasn't done smartly.  I had mulitple hits from the same IPs 
throughout the day, all aimed at a single IP on our network...which happens to be our incoming address for our exchange 
server.  

For anyone that was interested in this, I'll throw up a bit of my logs (IP's are faked below...when I did lookups on 
the IPs, it appeared the attacking address were probably compromised machines).  I didn't ever get a packet capture 
while the attack happend, so I won't be able to see exactly what they were trying to do (malformed packets, etc...).

Entire scan/attack lasted from 6:22am until 6:15pm CST on Jun 3.  Recieved a block of requests (icmp, 445, nbname) 
about 4-5 times a minute.  Probably 20 different addresses total.

Dest. Port -> Source Addy -> Dest Addy -> Protocol -> Source Port

                65.1.1.1                209.9.9.9       icmp            
445             65.1.1.1                209.9.9.9       tcp             1111
nbname  65.1.1.1                209.9.9.9       udp             nbname

                67.1.1.1                209.9.9.9       icmp
445             67.1.1.1                209.9.9.9       tcp             1098
nbname  67.1.1.1                209.9.9.9       udp             nbname



-----Original Message-----
From: Muhammad Faisal Rauf Danka [mailto:mfrd () attitudex com]
Sent: Tuesday, June 04, 2002 3:51 AM
To: incidents () securityfocus com
Subject: Re: Port 445 increase?


NetBIOS over TCP traditionally uses the following ports:

nbname 137/UDP
nbname 137/TCP
nbdatagram 138/UDP
nbsession 139/TCP

Direct hosted "NetBIOS-less" SMB traffic uses the following port:

MICROSOFT-DS 445/TCP
MICROSOFT-DS 445/UDP

Looks like you're being scanned for open shares (the usual), but the scanner/worm/potential intruder now knows about 
"NeBIOS-less" SMB traffic port too.

This could be a DoS Attack on port 445 too, see http://www.vnunet.com/News/1131065
but i doubt that since you said It was followed by nbname lookup, so It's probably looking for openshares.

Regards, 
---------
Muhammad Faisal Rauf Danka

Chief Technology Officer
Gem Internet Services (Pvt) Ltd.
web: www.gem.net.pk

Vice President
Pakistan Computer Emergency Responce Team (PakCERT)
web: www.pakcert.org

Chief Security Analyst
Applied Technology Research Center (ATRC)
web: www.atrc.net.pk


--- "Mike Hrubes" <MHrubes () wizmo com> wrote:
> Since around noon today (CST), we've really been getting hammered with tcp =
> 445.  Interestingly, it appears to be a tool or worm doing the scanning.  A=
> ll requests seem to follow the same basic format of ICMP, then 445, followe=
> d by nbname.  The requests are coming from many many different IPs, but are=
> all directed at a single box on our network.
>
> Just curious if anyone else out there is seeing anything like this?
>
> Thanks!
>
> MH

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