Dictionary Attacks?? 1

[rodentcentre]

You guys are going to get sick of me and my questions but I'm trying to learn so thanks ahead of time...I was looking through my SMTP queue and noticed a lot of wierd outgoing domains (such as sender-25-30100926-55@mx6.directsouthpro.com,
1.33745.36333439343133.1.b@ientrynetwork.net,
1.33763.36333439343133.1.b@ientrynetwork.net)...I looked at the contents of the messages and the outgoing e-mail address is postmaster@xxx.com...I plugged the symptoms into google and came up with Dictionary Attacks...The explanation was for both username/password guessing and also e-mail address guessing...Can someone explain to me why there would be outgoing messages from postmaster@xxx.com to these domains, whether or not I'm being paranoid, and what you can do to eliminate the possibility of it happening?? Thanks.

 

[TheGrey]

it could look like your smtp is an open relay..?
make sure it dont accept connections from everywhere, or your server can forward mail (spam, viruses, illegal content) for anyone

 

[rodentcentre]

Ok, on my Relay Restrictions I have Only the list below selected and have two IP addresses there; 192.168.1.0 and 192.168.1.12 and I have the Allow all computers which successfully authenticate to relay, regardless of the list above checked...am I ok??

 

[rliebsch]

Could also be bouncebacks to senders because of non-existant users on your domain.

 

[sab4you]

is it possible that one of the domain computers could be hosting some spam software? Would it be considered an authenticated machine allowed to relay?

 

[Davetoo]

If xxx.com is your domain, then it looks like NDR's going out to the Internet. You can disable them in SM if you want (not a bad idea), but in the business world that's not always the best thing to do.

Looks to me like spam and not some sort of attack.

I'm Certifiable, not certified.
It just means my answers are from experience, not a book.

 

[rodentcentre]

Thanks guys, I appreciate your feedback...I guess I'm paranoid

 

[Zelandakh]

Better paranoid than sticking your head in the sand and then getting hauled up in front of your Manager...

 

[B827]

Just because you are paranoid it doesn't mean that they are not out ot get you!

Sandy