Cortex XDR unable to detect nbns spoofing using kali linux responder

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Cortex XDR unable to detect nbns spoofing using kali linux responder

L1 Bithead

Hello, I am new to Cortex XDR, I  just installed it. I tried nbns spoofing on a pc with Cortex XDR and it did not stop or detect it. My previous test with Symantec was detected and stopped. Any thoughts on this? 


L4 Transporter

Hi @tech_noob-


Can you please provide a little more context?  Let's start with which Cortex XDR license type(s) are you running?






David Falcon 
Senior Solutions Architect, Cortex
Palo Alto Networks® 

I am using XDR prevent currently. My vendor made an error we are supposed to  get pro and I am waiting for the upgrade in the next week or so.

L3 Networker

Im curious what was detected on the endpoint for symantec to identify it as malicious behavior and stop it?

My understanding is that responder is listening for those multicast queries from your endpoint and responding when received.


Yes, Symantec detected it and stopped it on the endpoint. We upgraded our Cortex to Pro and I will test again under Cortex Pro maybe it will detect it as BIOC on the endpoint. I will post the result. 

Please comment when you have the results we have prevent and many of the web servers will not detect attacks at the network level with this protection

L1 Bithead

We now use Cortex XDR pro. We recently had had a  pen test internal audit, XDR detected port scanning etc. but it did not detect kali linux responder/nbns spoofing. Security auditor captured hashes but luckily they were not able to crack them. I tried Kali responder running on a VM, I rebooted my endpoint with XDR pro on the same LAN, and I was able to capture some hash with responder. From the XDR logs I am having a hard time finding IOC/BIOC I can use to detect and prevent responder...any thoughts on this? Our pen tester said that since the responder is passive it will be hard to detect. - thanks


L1 Bithead

We now use XDR Pro. We recently had an internal pen test, XDR detected port scanning, etc., but it did not detect and prevent nbns spoofing with Kali responder, some hash was captured but luckily they were not able to crack them. I ran responder on the same lan where I have a windows 10 with XDR pro. I rebooted Windows 10 and I was able to capture hashes with Kali responder.

I looked a the XDR logs but I am having a hard time finding IOC/BIOC for detecting responder..any thoughts on this? Thanks.

L3 Networker

Hello Tech_noob


Could you create a BIOC rule like below.



Network = Incoming, outgoing



5355 is LLMNR port number and as you know that, if clients cannot find/resolve a remote host in DNS, starting to LLMNR query via multicast. 

So, with this BIOC rule, You can detect LLMNR queried hosts and would be helpful to understand which process is responsible for the LLMNR.

with XDR you can control Windows Host firewall and block that UDP packages but from the security perspective (host hardening), Im gonna advise to use GPO for disabling LLMNR and Netbios name resolution. 






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