Basic Java Deserialization (ObjectInputStream, readObject)

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Katika chapisho hili, mfano utaelezwa ukitumia java.io.Serializable.

Serializable

Kiolesura cha Java Serializable (java.io.Serializable ni kiolesura cha alama ambacho darasa zako lazima zitekeleze ikiwa zinapaswa kuserilishwa na kudiserilishwa. Userilishaji wa vitu vya Java (kuandika) unafanywa na ObjectOutputStream na kudiserilishwa (kusoma) unafanywa na ObjectInputStream.

Hebu tuone mfano na darasa la Person ambalo ni linaloweza kuserilishwa. Darasa hili linabadilisha kazi ya readObject, kwa hivyo wakati kitu chochote cha darasa hili kinapodiserilishwa, kazi hii itatekelezwa. Katika mfano huo, kazi ya readObject ya darasa la Person inaita kazi eat() ya mnyama wake na kazi eat() ya Mbwa (kwa sababu fulani) inaita calc.exe. Tutaona jinsi ya kuserilisha na kudiserilisha kitu cha Person ili kutekeleza kikokotozi hiki:

Mfano ufuatao ni kutoka https://medium.com/@knownsec404team/java-deserialization-tool-gadgetinspector-first-glimpse-74e99e493649

import java.io.Serializable;
import java.io.*;

public class TestDeserialization {
interface Animal {
public void eat();
}
//Class must implements Serializable to be serializable
public static class Cat implements Animal,Serializable {
@Override
public void eat() {
System.out.println("cat eat fish");
}
}
//Class must implements Serializable to be serializable
public static class Dog implements Animal,Serializable {
@Override
public void eat() {
try {
Runtime.getRuntime().exec("calc");
} catch (IOException e) {
e.printStackTrace();
}
System.out.println("dog eat bone");
}
}
//Class must implements Serializable to be serializable
public static class Person implements Serializable {
private Animal pet;
public Person(Animal pet){
this.pet = pet;
}
//readObject implementation, will call the readObject from ObjectInputStream  and then call pet.eat()
private void readObject(java.io.ObjectInputStream stream)
throws IOException, ClassNotFoundException {
pet = (Animal) stream.readObject();
pet.eat();
}
}
public static void GeneratePayload(Object instance, String file)
throws Exception {
//Serialize the constructed payload and write it to the file
File f = new File(file);
ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(f));
out.writeObject(instance);
out.flush();
out.close();
}
public static void payloadTest(String file) throws Exception {
//Read the written payload and deserialize it
ObjectInputStream in = new ObjectInputStream(new FileInputStream(file));
Object obj = in.readObject();
System.out.println(obj);
in.close();
}
public static void main(String[] args) throws Exception {
// Example to call Person with a Dog
Animal animal = new Dog();
Person person = new Person(animal);
GeneratePayload(person,"test.ser");
payloadTest("test.ser");
// Example to call Person with a Cat
//Animal animal = new Cat();
//Person person = new Person(animal);
//GeneratePayload(person,"test.ser");
//payloadTest("test.ser");
}
}

Hitimisho

Kama unavyoona katika mfano huu wa msingi sana, "udhaifu" hapa unaonekana kwa sababu kazi ya readObject inaita kazi nyingine zenye udhaifu.

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Njia nyingine za kusaidia HackTricks:

• Ikiwa unataka kuona kampuni yako inatangazwa katika HackTricks au kupakua HackTricks kwa muundo wa PDF Angalia MPANGO WA KUJIUNGA!

• Pata swag rasmi ya PEASS & HackTricks

• Gundua Familia ya PEASS, mkusanyiko wetu wa NFTs ya kipekee

• Jiunge na 💬 Kikundi cha Discord au kikundi cha telegram au tufuate kwenye Twitter 🐦 @carlospolopm.

• Shiriki mbinu zako za kudukua kwa kuwasilisha PR kwa HackTricks na HackTricks Cloud repos za github.