The end of the year is always a good time for reflection. As you close out your year, I encourage you to ask: how did your style of hacking change and evolve in 2014? I suspect most of us have some answer to this question. We’re always learning and becoming informed by new tricks.
Here’s how my personal hacking-style has changed in 2014.
PowerShell for Post Exploitation
There’s a lot of enthusiasm for PowerShell in the offensive community. I feel that these enthusiasts are split into two camps though. One camp advocates PowerShell as a tool to bootstrap a payload without worrying about anti-virus. Another camp develops all of their post-exploitation tools in PowerShell and operates through these tools.
This year, I came into the second camp. I would always acknowledge that there was great capability in PowerShell. But, the difficulty using these scripts with the tools I know [Meterpreter, Beacon] prevented me from experiencing it first hand.
This year, I took the time to integrate PowerShell into Cobalt Strike’s Beacon payload and remove this hurdle. Immediately, my eyes were opened to a whole universe of post-exploitation tools I didn’t have before.
Veil PowerUp has changed how I elevate my privileges. Now, one of my standard items is to use PowerUp to find misconfigurations on the compromised target before I look at other options.
Veil PowerView has changed how I interrogate a network, enumerate trusts, and look for targets I can jump to laterally.
Almost all of my post-exploitation is asynchronous now. I go interactive only when I need to tunnel another tool through a Beacon.
Lateral Movement without PsExec
My tools tend to expose the Metasploit Framework’s workflow for lateral movement. Dump hashes and use the psexec module to get a session on a host. Or, steal a token and use current_user_psexec to get to that host. If current_user_psexec fails [it will], know how to run an artifact on a remote system the manual way.
The workflow for lateral movement I use today is much different. Late 2013, I introduced the named pipe communication channel into Beacon. I saw some interesting possibilities for this channel, but during use, I could tell the supporting features were missing. These came in February 2014. I added the ability to generate artifacts that contain the entire Beacon payload and Beacon gained tools to elevate privileges and steal tokens.
The above was enough to move my lateral movement workflow away from Metasploit’s workflows. I now capture a trust through Beacon [net use, steal a token, import a kerb ticket] and use wmic, at, sc, or schtasks to run an artifact I copy to the remote target. This artifact is almost always an SMB Beacon. This is the Beacon variant that waits for me to link to it over a named pipe. This is very stealthy and it’s a very powerful way to use Beacon. Almost all of my lateral movement is asynchronous now.
Persistence without Malware
Another big change to my process came from Mimikatz and the Golden Ticket technique. This technique allows me to use the krbtgt hash taken from a domain controller to generate valid Kerberos tickets for any user I like. These tickets are not tied to the user’s password at all. This technique has changed how I do persistence. Now, I tend to pull the information I need to generate tickets at will and store it in an attacker-accessible Wiki. When I need access to a server or some other key asset, I generate a ticket, import it into Beacon, take the server, and then pull off of it when I’m done.
For defenders used to finding malware and cleaning it up, this is a big mental shift. They can’t just delete a bad binary and assume their network is clean. They have to think about which trusts the attacker had access to and how that might allow the attacker to reclaim control of their network at will. It’s an interesting problem.
I’ve always appreciated living on hosts without malware. In exercises, the sticky keys backdoor is useful. Periodically using Mimikatz to pull credentials to (re)use later is also a way to hold access. These techniques are fine but they carry risk [the RDP backdoor is easy to find, vigilant admins change their passwords]. The Golden Ticket allowed me to have confidence in and rely on malware-free persistence in a way that I just couldn’t before.
In terms of my tradecraft and thinking about how I “hack”, these are the three things that changed for me in 2014. What changed for you?