Digging Deep Into The Hidden Networks

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You’re working in a corporate network where keeping critical systems and normal users in a single network is not recommended. Imagine yourself pentesting this network with n-layered security architecture, made intentionally to protect internal services, keeping Defense-In-Depth in mind.    

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This can be tricky…let’s dig in on how to work your magic.  

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Routing

This is the backbone process of the networking principles that determines how devices in WAN networks communicate. Routers (layer three devices) route the data packets to the relevant destination.

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Pivoting

In simple words, it’s a process of accessing an inaccessible network by taking leverage of a compromised host on the network.  

Using this tunneled routing, you can pivot all requests to the target inaccessible host via compromised host.  

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Behind the Scenes – Pivoting Process

The compromised host is connected to the router that connects to the demilitarized zone (DMZ) with privileges to access the systems (for example: a user authorized to access DMZ).

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Time to use metasploit:  

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Let’s Pivot  

Remember routing? Let’s talk about it more. Once the first target is compromised, you can then create a custom routing rule for pivoting.  

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With the autoroute session in place, you can access the 8.8.8.0/24 network. Arp scanner would be good, right? Let’s see how an attacker uses it:

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Sweet! Now, it’s time to have some fun utilizing pivoting. As the session is already initialized, routing configurations can be forwarded over a sock4 proxy that can be used within a Metasploit framework.  

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Once it’s set up, port forwarding is the way to go, which is available within the Metasploit framework as a module. With a local port, you can forward a connection request to a port available on the target 8.8.8.2

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With a nmap scan using proxychains, you can figure out what ports open on the target that you can use to add for port forwarding.  

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Digging down further, you can use the browser and visit port 9090 on your machine to check the service on port 80 of the target.  

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Voila! Now you can try tools like hydra to guess credentials for login. If not, find your way in with known exploits for the running services.  

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Strategies to Mitigate these types of Risks

• Setup systems in the DMZ structure to be accessible only within DMZ structures.

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Ramandeep Singh is a lead instructor with Evolve Security Academy and a consultant with Evolve Security. You may contact him at connect@evolvesecurity.io.

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