My observations while working this target:
· Enumeration: CTF-like /Life-like
· Vulnerabilities: CTF-like/Life-like
· Exploitation: CTF-like/Life-like
· Difficulty: Medium
· Community Notes: CTF-like
The recommended tools for this machine were:
The following vulnerabilities were found:
· Local File Inclusion (LFI)
· Local Privilege Escalation (2x)
Using Nmap, I performed a SYN scan on all TCP ports for service version detection as well as default safe scripts.
After identifying ports 80 and 9200 as HTTP, I performed a Gobuster scan on both ports.
Reviewing the findings from Nmap and Gobuster, I decided to launch a browser to further investigate both HTTP ports.
TCP Port 80 revealed an image and no other information useful information.
Reviewing the TCP Port 80 web site a little closer, I used Curl to determine if there was anything that might have been hidden on the port itself.
Still not finding anything interesting, I decided to use Curl to download the needle.jpg file for further investigation.
Not having any luck with identifying Steganography, I used Strings and revealed a Base64 encoded line at the end of the image file.
Next, I launched the Base64 application to decode the message and found the cleartext being in Spanish. Since my Spanish was not that strong, I found a web site to translate the message.
Not finding any other interesting information from TCP Port 80, I turned to reviewing TCP Port 9200; where I found that the ElasticSearch had a searching mechanism that I used to search the /quotes directory.
Not finding much with the browser search, I manually discovered that there were multiple pages contained within the /quotes directory. I stumbled across one of the pages that provided a hint that a search would need to be performed.
I started to review the ElasticSearch web site and found a manual for the product. Using their examples, I used Curl to search for all contents within the /quote* directory.
Next, I used the “key word” found, from the image obtained from TCP Port 80, to search the /quotes directory; where I found additional Base64 encoded lines.
Using the previously found Spanish translator, as well as, the Base64 application, I was able to determine that I obtained credentials to the target.
With the credentials obtained, I decided to try them against the SSH port discovered earlier with Nmap.
Awesome. Having established a foothold to the target, I then obtained the User Flag.
Local File Inclusion (LFI):
With the User Flag secured, I decided to enumerate the target locally with linPE. I came across more Spanish within the Services section.
Next, I returned to the attacker system to perform another Curl against the target to help me enumerate.
Remembering that I had discovered what appeared to be a version number, I returned to the web browser using the ElasticSearch _search function for the entire target.
Having pretty firm evidence that there was a Kibana backend server, I reviewed the ElasticSearch documentation for clues on where I could find configuration files.
Not having much luck with the loopback connection to TCP Port 5601, I performed an Internet search and found a few CVE’s that I could possibly use to exploit the application.
I eventually found a GitHub site that had a POC for CVE-2018–17246. After reviewing the information, I copied the code for the Java Shell for use on the target.
With the shell code copied to the target’s /tmp directory, and a NetCat listen launched on my attacker system, I used Curl to launch the LFI attack.
After the successful LFI exploit of Kibana, I still did not have root access. So, I performed additional enumeration with the newly acquired user account. I eventually found that the kibana user had Read/Write access to the /etc/logstach directory.
Continuing to enumerate the conf.d directory, I found three configuration files that looked interesting. So, I returned to the ElasticSearch manual to review what the configuration files were used for.
After identifying that the configuration files we used for filtering, I reviewed each of the files based on the ordered used by Logstash.
This took me a bit, but the input configuration file looked at the /opt/kibana directory for a logstash_* file with a wildcard. The filter then launched any wildcard file on an interval of 10 seconds.
The grok filter configuration file used regex when identifying the key word of “Ejecutar comando : <command>“ to be utilized within the logstash_ file to search and launch.
The last configuration file, of output, executed the command found within the filter.
So, tying it all together, I created an executable file of logstach_123 to launch a reverse Bash shell to my attacker system with a NetCat listener.
After identifying that I had root, I located the Root Flag.
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