Friday, September 12, 2014

El Jefe - Alerts

In the never ending cat and mouse game between offense and defense, the defenders generally represent the mice. The objective of vulnerability management is to flip the script on the proverbial felines and set functional mouse traps for them. We can do this using machine learning to predict a potential attack vector or, if you feel like being an oxymoron, by deploying a fast and effective clean up.

Polemic methodologies such as "0day feeds" are ineffective as they protect against samples, not classes. While useful to demonstrate actionable risk to management, catching a single instance of a vulnerability implementation (AKA exploit) , 0day or otherwise, does very little to effectively protect you at an enterprise scale against similar vulnerabilities. Shooting fish in a barrel generally does not equate to a sane defensive posture.

El Jefe Alerts is our approach to a more comprehensive methodology of vulnerability management.

With El Jefe Alerts you are able to use, share and extend scenario driven vulnerability heuristics for entire vulnerability classes that trigger well defined response events.

A simple example:  Suppose every time iexplorer.exe parents an executable anywhere in your enterprise I want to retrieve the executable, run it through a sandbox and then receive an event summary via email. We can do that with El Jefe Alerts.

Or suppose that every time iexplorer.exe's virtual size gets bigger than 2 GB we would like to receive an urgent SMS, as this is a likely indicator of a heap spray in progress. We can do that with El Jefe Alerts.

What if I want to be notified whenever someone in the Enterprise launches a certain executable outside of work hours? Not a problem for El Jefe Alerts.

Let's walk through a simple example of how to set up an El Jefe Alert.

If you've attended DEFCON in the last three years, you probably noticed a distinct pattern in any presentation that involves Windows exploitation. Namely that a lot of attacker demos end up executing calc.exe! It seems they consider math a very important step of their post-exploitation strategy. Lets ruin their 4th grade algebra aspirations with the following:
1) The first step is to create a Filter, which is the module responsible for the heuristic that will trigger the El Jefe response action. Filters are django models which you can find in the alerts/ file.

ExecutionFilter will be triggered when a binary filepath is on our blacklist

You create the model and you implement the heuristic in the "filter" function. In this case, we want to trigger an action if and when an executed binary is listed in our blacklist.

2) The second step is to create an El Jefe Action script. The Action script defines the El Jefe response action to a filter trigger event. You can define multiple actions per filter. In our example script, we create a simple file that just prints some basic information about the event, and we place it in the xmlserver/actions/ folder.
A simple action that will print the username, ip and binary executed

3) The final step is to put everything together. Once we've implemented our Filters and Alerts, they will automatically show up in the El Jefe interface.

You can now go to the "Alerts" section in the navigation bar, and select "Add". You select your Filter and associate one or more Actions and then select the executables you want to keep track of.
Adding a working filter
4) Voila! You are now Busticati proof!
Gotcha! You should never do your math homework on a compromised machine!

In real life, this simple Alert is useful when  you have recognized a particular pattern with an attacker - for example, many of them use WMIC.exe because that is how metasploit's meterpreter and some other trojans do their WMI activity (for enumerating all sorts of important system information). Normal users almost never use WMIC.exe so this is an interesting heuristic to apply across your network. For the record, INNUENDO does not shell out to WMIC - it has WMI support built into it.

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