CVE-2021-44228 PoC — Apache Log4j2 JNDI features do not protect against attacker controlled LDAP and other JNDI related endpoints

Source

Associated Vulnerability

Description

Fixes CVE-2021-44228 in log4j by patching JndiLookup class

Readme

# log4j-vulnerability-patcher-agent

This agent fixes critical vulnerability [CVE-2021-44228](https://www.lunasec.io/docs/blog/log4j-zero-day/) in log4j by patching `JndiLookup` class, as recommended [here](https://www.lunasec.io/docs/blog/log4j-zero-day/#temporary-mitigation).

**WARNING: this is not a substitute for proper upgrade to log4j 2.15.0**, where this vulnerability was fixed for good. Use this agent **IF, and ONLY IF, you can't upgrade log4j in your app**.

Agent can run on JRE 8 and higher, in any application (including Minecraft clients and servers).

This will completely disable `JNDI` in log4j. If you need this functionality, do not use this agent.

## How to use

1. Download agent JAR or build it yourself
2. Add command line argument `-javaagent:/path/to/agent/log4j-vulnerability-patcher-agent.jar` to the start command of your app

Example command line:

```shell
java -javaagent:/home/user/log4j-vulnerability-patcher-agent.jar -Xmx1G spigot.jar
```

If everything is OK, on start agent will output `[Log4jVulnerabilityPatcherAgent] JndiLookup was patched, vulnerability fixed!`.

## Build

You will need JDK 8, Maven and Git.

```shell
git clone https://github.com/saharNooby/log4j-vulnerability-patcher-agent.git
cd log4j-vulnerability-patcher-agent
mvn clean package
```

File Snapshot

 [4.0K]  /data/pocs/73d3df7018ca631fdc4dca1dce245ff7af5be4af
├── [1.1K]  LICENSE
├── [2.7K]  pom.xml
├── [1.3K]  README.md
└── [4.0K]  src
    └── [4.0K]  main
        └── [4.0K]  java
            └── [4.0K]  me
                └── [4.0K]  saharnooby
                    └── [4.0K]  agent
                        └── [4.0K]  minecraft
                            └── [4.0K]  log4jfix
                                ├── [1.2K]  Main.java
                                └── [1.1K]  Patcher.java

8 directories, 5 files

Remarks