Author Archive

SSH Client as a Quick and Dirty Port Scanner

by on Jul.22, 2022, under Posts

Since the ssh client is pretty ubiquitous and has been included with Windows 10 installations for the past couple years, I’ve discovered it can be a useful tcp port scanner if you use the verbose flag:

For Windows:

ssh -p 80 google.com -v 2>&1 | findstr Connect

ssh -p 80 -o ConnectTimeout=1 www.google.com -v 2>&1 | findstr Connect
debug1: Connecting to www.google.com [142.250.191.228] port 80.
debug1: Connection established.
kex_exchange_identification: Connection closed by remote host

As for your *nix systems, just use grep instead of findstr. I hope someone else finds this useful!

 

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Domain Controller/Active directory over Meraki VPN fix

by on May.03, 2022, under Posts

If you have a Meraki setup that has Umbrella tied into it, and you can’t communicate properly with your *.local domain controller over the Meraki VPN, I have a potential fix for you. In my scenario, VPN clients could see the domain controllers and DC IP addresses were specified as DNS servers which would properly assigned to VPN clients. VPN clients could query DCs for external DNS names without any issues but any *.local communications or gpupdate related commands would fail. I troubleshooted it to the nth degree and discovered this fix:

Go to Security & SD-WAN, then to configure, and then to threat protection. Scroll down to the Umbrella protection section and specify your local domain name (mydomain.local) as an exception from being routed to Umbrella. Saves your changes and hopefully this resolves your issue.

If you continue to have issues, double check that your VPN clients and see what DNS servers are getting assigned. Some individuals had to change the metric (hint lower the number, route print to find metrics of adapters).

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Cisco Meraki security is kind of a joke…

by on Dec.11, 2021, under Posts

Recently I wanted to test Meraki’s ‘Threat Protection’ system and see if it was really up to snuff. First, I setup an up to date Windows 10 virtual machine where I disabled the anti-virus on this system.  In this environment there isn’t any SSL inspection being done by Meraki and to my understanding, Cisco really doesn’t advocate using SSL inspection through Meraki. In my opinion, you are already at kind of a disadvantage with the lack of SSL inspection because most threats that need to be seriously considered will use encryption for evasion. Metasploit’s meterpreter payload has supported SSL and encryption for years. Plus you can setup legit certs for free if needed.

With that being said, I thought I would throw a softball at Meraki and see if it would do some sort of detection via HTTP. I tried downloading the benign eicar test file over HTTP and Meraki blocked it:

However, if you download the same file over HTTPS, Meraki does not block it (no surprise there).  I then decided to step my game up and generate a payload using msfvenom and host it on a python3 http server ( python3 -m http.server ):

I was able to download the payload using powershell on the victim VM:

I was then able to run the payload on the victim system and have a session:

Meraki did not detect the payload or the session.. and here’s the the virustotal report for this payload:

https://www.virustotal.com/gui/file/f7f301b9bb52a23efb1c6e5ee4f2bb6adeebda2882a60c9f98ca582100b78908/detection

This payload was not made in really any special way… it’s a pretty standard payload that I believe ALL IDS/IPS systems should be able to detect or block. However, I will give credit where credit is due. Later on I did receive an alert that this payload had slipped through:

Additionally, this Meraki configuration does not have Cisco’s Umbrella integrated yet. Would Umbrella have blocked it? I honestly don’t know but what I’m willing to test it.

I would like to add that a majority of events that I’ve seen under Security Center have been false positives. There is already enough noise in terms of information pertaining to networks. Meraki generating this just adds more unnecessary noise and can hamper investigations in my humble opinion.

I’m still thoroughly disappointed with this discovery because people are paying Cisco a lot of money for a false sense of security. Meraki should have blocked this threat right away. In the end of the day, I believe having well trained employees and thorough AV/EDR systems on endpoints is what matters most.

#Update 12/24/2021

I have setup the Umbrella client on the victim VM. Meraki blocked the known helpme.exe file, however if you simply use the shikata_ga_nai encoder to make a new file called helpme2.exe, this payload slipped through Meraki and Umbrella.

Here is the virustotal.com report for the file:

https://www.virustotal.com/gui/file/19cf577ac24452bfb715f421a6bdabadd0f2d043f60cbbf600e44e34dc14738f

I feel like I can confidentially say that Meraki/Umbrella security are a joke.

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IPMI EVERYWHERE! w/The Pi-KVM – Level1Techs

by on Sep.26, 2021, under Videos

 

https://pikvm.org/

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