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Setting up a Windows 7 Kernel Development Environment

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If you are writing some Ring0 (or privileged mode code), say something like device drivers in Windows you’d probably be better served with a separate development machine and a deployment machine. This helps you to write poor code and still not lose hair because your development machine blue screens! ūüôā

My setup was using a Windows 8.1 development machine and a Hyper-V based Windows 7 machine for debugging. You will need to execute different tasks on the “guest” (Hyper-V based Windows 7 virtual machine) and some other tasks on the development machine. ¬†I followed many of the things from the MSDN blog post here

On your guest machine you would want to setup a named pipe and setup debug settings. To do that this is what you need to do:

Setup a virtual com port in the Hyper-V Settings (File -> Settings) , this port will be used to communicate from the host machine to the guest to communicate the Kernel debugging commands.
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Now make sure that your target guest machine is configured to “listen” those commands. ¬†Inside the guest VM, start a command shell (cmd.exe -> Run as Administrator).

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Configure the bcdedit commands so that the machine can now be debugged.  Right after the 2nd command, reboot your Virtual Machine.

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With the VM now configured to listen the debug commands via the COM1 port, and the debug mode on in the bootup settings, now start the WinDbg x64 on the host (using “Run as administrator”; you need administrative privileges for communication via Serial port). ¬†In your kernel debugger on the host or the development machine (I’m assuming that these are both on the same physical hardware here). ¬†Click on File -> Kernel Debug and you should see the following screen in the WinDbg window:

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Hit Ctrl+Break or Debug -> Break and you will see something like this:

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Just remember that when you break in the debugger, your guest in Hyper-V should become “unresponsive”. ¬†The only thing is that it is not¬†really unresponsive, its just being debugged. ¬†Just to make sure, that you have the symbols package that is quite useful for debugging run the following command:

!process 0 0

If you see something like the following screen show up:

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The following error means that the symbols are not defined.  Symbols help the debugger give more information about the commands that you are going to execute in the debugger.

**** NT ACTIVE PROCESS DUMP ****
NT symbols are incorrect, please fix symbols

To fix this, use the following commands:

kd> .sympath SRV*c:\symcache*http://msdl.microsoft.com/download/symbols
kd> .symfix
kd> .symfix c:\symcache
kd> !sym noisy
kd> .reload /o

Then again try the command: !process 0 0 and see if you get a good response.  A good response looks like the following:

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With this you should be good to go! Happy debugging and writing cool Ring0 code.

 

 

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Reverse tunnels

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SSH is an excellent piece of software which can help you do a lot of things such as have encrypted shells etc. But what makes SSH incredibly flexible is having tunnels.

A typical ssh tunnel works from the client to the ssh server and it forwards a local port on the client to the server seamlessly.

client ----> ssh_conn ----> ssh_server
client --> tunneled_port --> ssh_server
ssh -L 10000:localhost:10000 username@ssh_server

This connection creates a tunneled port on client:10000 i.e., anything sent to this port appears as if it’s automatically sent to ssh_server on port 10000. The localhost here is confusing, but think of it as….”what is localhost for ssh_server?”. It would be the ssh_server itself, right?
If you do a netstat on the client, you see a listener on the port 10000/tcp.

Now comes the more interesting reverse tunnel. The reverse tunnel is different in that, you have a tunnel being initiated by the client that says to the ssh server, “Hey, I’m initiating this connection that will allow you to automatically access a port on *me* after *I* initiate the connection?” (confused!!?!)

client ---> ssh_connection ---> server  ---+
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client <-- tunneled_port  <----- server ---+
ssh -NR 10000:localhost:10000 user@ssh_server

Here the meaning of localhost is slightly different, though.¬† The “localhost” means what is localhost for the client (and not on the server as in the previous case)!¬†¬† So what you’re saying is, “Hey SSH server, I’m initiating this connection to you but if you connect to your port 10000 you will get a tunnel to *my* port 10000.”¬† If you do a netstat on the server you see a listener on port 10000. Isn’t it great that you can make the server listen to a port which acts as a tunnel to you…so anyone on the server can seamlessly connect to you even though technically you were the client!

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Echo Mirage and UHooker

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It can get interesting to test the security of thick client applications. If you start debugging you could end up losing a lot of time with not too many results. Of course, time is always at a premium when you pen testing in a week long gig. There are a couple of tools that can really help you to gain insight into a thick client (i.e., an application written in a binary format such as an executable, ActiveX control, flash object, etc.) and communicating to a server using the client/server model.
The need for a proxy to hook into the communications is a prime need and EchoMirage can do a great job of hooking into function calls related to win32 sockets, openssl functions. You have to select an active process for Echomirage to inject into or you can even spawn a process from the menu options in EchoMirage itself. It’s a great tool with a built-in editor so you can edit the traffic. However, sometimes you have to be careful because it’s binary data that you are editing so while editing it is easy to mess up a few flags, etc.
Another great tool is actually a plugin for OllyDbg called UHooker that can let you specify which functions you want to place a hook into. You have to configure a binary editor of your choosing and the functions to be hooked into in a .cfg file. The documentation for Uhooker is located here.

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Start the Blog!

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Just started blogging…actually getting pretty late into the blogging culture! Studying and doing projects to complete graduation at USC. My homepage is at http://www-scf.usc.edu/~swarup/.

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Modern-day Reconnaissance

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Back in the day “recon” had a different meaning than it does today. Today, in the age of cyber-terrorism and cyber-stalking or Google stalking, reconnaissance comes from a variety of different sources including tools such as mash-up applications make things quite palpable for a social engineer. For the purpose of this discussion, let’s consider two entities “stalker” (the person seeking information about “someone”) and the “stalkee” (the “someone” whose information is being sought).
Back in the day (and man I’m only talking about 4-5 years ago!), the only source was public forums where users would post questions using constant email IDs. You would need to scourge through different Usenet groups and that was it…and possibly a Friendster account. Now, people have Facebook profiles which can be publicly viewed. This gives us the information about a person’s friends giving us information about the stalkee’s geographical location and may be even birthday. LinkedIn gives information about the stalkee’s job. You can even confirm the geographical location of the stalkee using LinkedIn. Now you have the name of the person and the geographical location. If you need more information about the person such as his/her age/birthdate, I’ve seen that ZabaSearch is a good resource. You can get a lot of information using ZabaSearch but if the stalkee needs he/she can remove this information using the block feature of Zaba located here. I do not know how they deal with this information but Zaba does have a “premium service” and I do not know if this premium service would give access to these “blocked records”. Now you have the information about the age of the stalkee. You could even search Twitter for the person’s twitter feed to see what the stalkee’s doing. I came across an interesting mashup application that crawls twitter to get information about where a person is and it’s aptly called Please Rob Me!. There are other great tools available such as Loopt and Tripit. Just as Twitter, Google Buzz can also give a lot of information. And the best part about google buzz is things are searchable …cool…the stalker’s job’s now easier.

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Verizon FiOS and PS3 Media Server Streaming Issues

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If you’re like me and recently upgraded to Verizon FiOS and you have your PS3 on the wired segment and the Media Server (such as PS3 Media Server, TVersity, etc.) on the wireless segment, you’re in for a ride with the configuration.
By default, you can’t route the traffic between the wired and wireless segments over UDP! You can send ICMP echo packets (i.e., ping) but the PS3 just won’t detect the Media server. You may disable the Host-based firewall (e.g., Norton, Kaspersky, McAfee, etc.) but it still won’t work.

If you happen to read posts like these, you will see that you have to disable “IGMP proxy”. IGMP Proxy basically reduces the traffic on the multicast addresses to a bare minimum. Unfortunately for you, this causes the traffic between PS3 Media Server and PS3 to drop.

So you log into your FiOS router’s administration console typically located at 192.168.1.1. Click on Advanced -> Yes -> Firmware Upgrade and check the firmware version. You will see that it is an ActionTec router (based on the Auto-update URL). But nowhere do you see the option to update the “IGMP Proxy” settings. That’s because that feature is “hidden” in the latest firmwares.

So you just need to copy/paste the following URL into the browser address bar and you will see the option to disable “IGMP proxy”.
http://192.168.1.1/index.cgi?active_page=6059
Disable it and Voila! The PS3 Media Server and PS3 can now talk to each other.

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Cisco VPN Client on BackTrack3

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I wanted to install Cisco VPN client on BackTrack3. You can get the Cisco VPN client source using the following command:
wget ftp://ftp.cs.cornell.edu/pub/rvr/upload/vpnclient-linux-4.8.00.0490-k9.tar.gz
tar zxvf
vpnclient-linux-4.8.00.0490-k9.tar.gz
cd vpnclient/
wget http://tuxx-home.at/projects/cisco-vpnclient/vpnclient-linux-2.6.22.diff
patch < vpnclient-linux-2.6.22.diff
./vpn_install

I got this information from the following blog.
I ran into an error whereby the kernel sources were not found for the VPN client to install. I then got the BackTrack3 kernel sources.
cd /lib/
wget http://www.offensive-security.com/kernel.lzm
mkdir test
lzm2dir kernel.lzm test

Now go into the vpnclient directory and execute the following:
./vpn_install

Accept the defaults (except in my case I selected “No” on automatically start VPN client). When it asks for the sources point it to:
/lib/test/usr/src/linux-2.6.21.5

Then the VPN Client should compile without any issues. Then you just need to place your Cisco VPN client Profile (.pcf) in the /etc/opt/cisco-vpnclient/Profiles directory. You will need to first start the VPN client service first using:

/etc/init.d/vpnclient_init start

Once the service is started just connect using:

vpnclient connect mypcffile user test password <whatever>

Please note that the full name of the Profile file in the above case is mypcffile.pcf but I’ve deliberately excluded the .pcf extension.
This should work.