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https://github.com/DCSO/mauerspecht

Simple Probing Tool for Corporate Walled Garden Networks
https://github.com/DCSO/mauerspecht

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Simple Probing Tool for Corporate Walled Garden Networks

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README 

        
```

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+ \"| | thcepsreuaM | |"/

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# Simple Probing Tool for Corporate Walled Garden Networks



The Problem: Network sensors such as

[Suricata](https://suricata-ids.org/) or [Bro/Zeek](https://zeek.org/)

have been successfully deployed in a large network, but the rate of

alarms or other useful information is suspiciously low -- not even the

usual background noise can be seen. Can we be sure that our sensors

are fed all the relevant traffic?



An attempt at a solution: Let's generate some network traffic and see

if we can transmit some magic strings to and from the outside world

beyond our walled garden network -- and if we are able to detect those

using our sensors.



## Operation



From a user perspective:



1. Generate a server configuration file that defines TCP ports and

   magic strings to exchange (see below for an example). Configure

   matching alerting rules in the network sensors.

2. Start the server on a publicly accessible host.

3. Start clients with the `-server` parameter pointing to one of the

   HTTP ports served by the server.

4. Analyze logs generated by the server and the network sensors.



The server writes its log output to standard error.



What happens behind the scenes:



1. On startup, both server and client generate private/public NaCL key

   pairs.

2. The client posts its public key to the server and receives the

   server's public key

3. The client requests the server's configuration. The configuration

   is signed/encrypted to circumvent tampering by middleboxes.

4. The client runs a few experiments, expecting every configured magic

   strings to be correctly transmitted via a special header, a Cookie

   or _Set-Cookie_ header, the message body.

5. The client posts its findings to the server.



### Example server configuration file



```

{

    "hostname": "mauerspecht.example.com",

    "http-ports": [8080, 18080],

    "magic-strings": [

        "unique-match-string-18475910",

        "START_KEYLOGGER",

        "X5O!P%@AP[4\\PZX54(P^)7CC)7}$EICAR-STANDARD-ANTIVIRUS-TEST-FILE!$H+H*"

    ]

}

```



### Command line parameters



Client:

```

  -server string

    	Server URL (default "http://localhost:8080")

  -proxy string

    	Proxy URL

```

Server:

```

  -config string

    	Config file (default "mauerspecht.json")

```



## Building



If a Go toolchain with [modules](...) support is available (version

1.11 or later), simply running `make all` from the Git checkout is

sufficient.



For earlier Go versions, run `go get github.com/DCSO/mauerspecht`

change to the directory within the `GOPATH` where the project was

downloaded, and run `make all`



In both cases, the following binaries will be generated:

- `mauerspecht-server`: The server component, a Linux/x86-64 binary

- `mauerspecht-client-$ARCH`: The clients, for various architectures



## Limitations, possible future features



- HTTPS -- self-signed server certificates, possible use of client certificates

- Non-HTTP protocols (IRC?)

- The server stores session keys submitted by clients in memory and does

  not expire them yet. This is a denial-of-service vector.

- Bundled client configuration for easy single-binary deployment (see

  also: [spyre](https://github.com/DCSO/spyre))



## Author



Hilko Bengen <>



## Copyright



Copyright 2019 Deutsche Cyber-Sicherheitsorganisation GmbH



This program is free software: you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation, either version 3 of the License, or

(at your option) any later version.



This program is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of

MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

GNU General Public License for more details.



You should have received a copy of the GNU General Public License

along with this program.  If not, see .