Solved

Spam Botnet on my LAN - How can I use the Sonicwall to identify the culprit?

Posted on 2014-01-22
7
1,664 Views
Last Modified: 2014-01-23
I have a Sonicwall TZ100 configured as a network edge device, and I was just blacklisted because my Firewall IP is shown sending SPAM messages.  I have setup a rule blocking all SMTP out with the copiers and Servers as exceptions and we have not been re-listed.

The infection persists on the network, however, and I am unable to track down where it is coming from.

How can I use the Sonicwall to see which host(s) are sending email now that the rule is blocking?  I cannot figure out how to see this with the log settings, it's pretty awful.

Thanks!
0
Comment
Question by:jkeegan123
  • 3
  • 2
  • 2
7 Comments
 
LVL 7

Expert Comment

by:Ned Ramsay
ID: 39800728
If you look in the firewalls logs you should see that the "block" rule you set up is being hit a lot by a specific host.

Downloading wireshark network analyser and then filtering the protocol by SMTP may help locate the PC

Alternatively if the reporting on that device isnt great and you cant find it with wireshark then add an "allow" rule above the deny rule for a small selection of IP addresses on your network.

e.g. if you have 100 devices on your network then allow 1-25 and see if it still spams. Then 26-50 etc. That will narrow it down to one section.

Edit: On my Sonicwall (larger version), I go to Dashboard then Connection Monitor. I can filter by destination port (25 for SMTP) and it shows a list of hosts using that.
0
 
LVL 5

Author Comment

by:jkeegan123
ID: 39800753
What should I look at in the log to see the BLOCK rule?  The new Sonicwall log is broken up into sections and it's not very friendly....to say the least!
0
 
LVL 5

Author Comment

by:jkeegan123
ID: 39800756
(ALSO Wireshark is not really an option since it's TCP, not a broadcast protocol, and we do not have a managed switch to port mirror the inside firewall interface.  We just wouldn't get the SMTP traffic showing up).
0
Create the perfect environment for any meeting

You might have a modern environment with all sorts of high-tech equipment, but what makes it worthwhile is how you seamlessly bring together the presentation with audio, video and lighting. The ATEN Control System provides integrated control and system automation.

 
LVL 7

Expert Comment

by:Ned Ramsay
ID: 39800784
If you filter wireshark using: tcp.port == 25 then it will show SMTP traffic on your network (I just tested on mine with no port mirroring)
0
 
LVL 25

Accepted Solution

by:
Diverse IT earned 500 total points
ID: 39800841
Hi jkeegan123,

You can do this by looking at the logs. What version of SonicOS are you running?

You don't need wireshark you have a solid packet capture within your TZ 100 under System > Packet Monitor if you need that. If you have the logs setup correctly (mark All Categories selected and Logging Level set to Debug, click Accept to save) you should be able to see the LAN IP being blocked by the LAN > WAN Access Rule #.

Let me know if you have any other questions!
0
 
LVL 7

Expert Comment

by:Ned Ramsay
ID: 39800900
Good answer by DiverseIT ^^ sorry I dont have a tz100 available to me.
0
 
LVL 25

Expert Comment

by:Diverse IT
ID: 39805078
Glad I could help...thanks for the points!
0

Featured Post

Microsoft Certification Exam 74-409

Veeam® is happy to provide the Microsoft community with a study guide prepared by MVP and MCT, Orin Thomas. This guide will take you through each of the exam objectives, helping you to prepare for and pass the examination.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

If you're not part of the solution, you're part of the problem.   Tips on how to secure IoT devices, even the dumbest ones, so they can't be used as part of a DDoS botnet.  Use PRTG Network Monitor as one of the building blocks, to detect unusual…
PRTG Network Monitor lets you monitor your bandwidth usage, so you know who is using up your bandwidth, and what they're using it for.
Here's a very brief overview of the methods PRTG Network Monitor (https://www.paessler.com/prtg) offers for monitoring bandwidth, to help you decide which methods you´d like to investigate in more detail.  The methods are covered in more detail in o…
This video gives you a great overview about bandwidth monitoring with SNMP and WMI with our network monitoring solution PRTG Network Monitor (https://www.paessler.com/prtg). If you're looking for how to monitor bandwidth using netflow or packet s…

685 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question