Burp Suite API插件开发指南：篡改WebSocket报文<\/h1>

1. 背景与概述<\/h2>
WebSocket协议相比HTTP具有更低的传输开销，广泛应用于即时聊天、在线游戏、实时位置等低延迟、高并发的服务场景。随着Burp Suite新版本对WebSocket的支持，开发者现在可以通过API插件来拦截和篡改WebSocket报文。<\/p>

2. 模拟场景<\/h2>
本教程基于一个GoLang编写的简易聊天室项目，该场景具有以下特点：<\/p>
前端使用JavaScript计算消息的SHA-256哈希值<\/li>
哈希值附加到消息中一起发送至服务器<\/li>
后端校验哈希值，校验失败则返回错误信息<\/li> <\/ul>
3. 插件开发步骤<\/h2>

3.1 初始化插件<\/h3>
package<\/span> arr;<\/span>
<\/span><\/span>
<\/span><\/span>import<\/span> burp.api.montoya.BurpExtension;<\/span>
<\/span><\/span>import<\/span> burp.api.montoya.MontoyaApi;<\/span>
<\/span><\/span>import<\/span> burp.api.montoya.logging.Logging;<\/span>
<\/span><\/span>
<\/span><\/span>public<\/span> class<\/span> WebsocketExample<\/span> implements<\/span> BurpExtension {<\/span>
<\/span><\/span>    MontoyaApi api;<\/span>
<\/span><\/span>    Logging logging;<\/span>
<\/span><\/span>    
<\/span><\/span>    @Override<\/span>
<\/span><\/span>    public<\/span> void<\/span> initialize<\/span>(<\/span>MontoyaApi api)<\/span> {<\/span>
<\/span><\/span>        \/\/ 保存对 MontoyaApi 对象的引用
<\/span><\/span><\/span><\/span>        this<\/span>.<\/span>api<\/span> =<\/span> api;<\/span>
<\/span><\/span>        \/\/ 获取日志对象
<\/span><\/span><\/span><\/span>        this<\/span>.<\/span>logging<\/span> =<\/span> api.<\/span>logging<\/span>();<\/span>
<\/span><\/span>        \/\/ 设置扩展名称
<\/span><\/span><\/span><\/span>        api.<\/span>extension<\/span>().<\/span>setName<\/span>(<\/span>"WebsocketExample"<\/span>);<\/span>
<\/span><\/span>        \/\/ 打印加载消息
<\/span><\/span><\/span><\/span>        this<\/span>.<\/span>logging<\/span>.<\/span>logToOutput<\/span>(<\/span>"*** Burp Suite API插件开发指北 - WebsocketExample 已加载"<\/span>);<\/span>
<\/span><\/span>        \/\/ 注册WebSocket处理器
<\/span><\/span><\/span><\/span>        api.<\/span>websockets<\/span>().<\/span>registerWebSocketCreatedHandler<\/span>(<\/span>new<\/span> CustomWebsocketCreatedHandler(<\/span>api));<\/span>
<\/span><\/span>    }<\/span>
<\/span><\/span>}<\/span>
<\/span><\/span><\/code><\/pre>3.2 创建WebSocket监听器<\/h3>
创建一个实现WebSocketCreatedHandler<\/code>接口的类来处理WebSocket连接创建事件：<\/p>
package<\/span> arr;<\/span>
<\/span><\/span>
<\/span><\/span>import<\/span> burp.api.montoya.MontoyaApi;<\/span>
<\/span><\/span>import<\/span> burp.api.montoya.logging.Logging;<\/span>
<\/span><\/span>import<\/span> burp.api.montoya.websocket.WebSocketCreated;<\/span>
<\/span><\/span>
<\/span><\/span>public<\/span> class<\/span> CustomWebsocketCreatedHandler<\/span> implements<\/span> WebSocketCreatedHandler {<\/span>
<\/span><\/span>    private<\/span> final<\/span> MontoyaApi api;<\/span>
<\/span><\/span>    private<\/span> final<\/span> Logging logging;<\/span>
<\/span><\/span>    
<\/span><\/span>    public<\/span> CustomWebsocketCreatedHandler<\/span>(<\/span>MontoyaApi api)<\/span> {<\/span>
<\/span><\/span>        this<\/span>.<\/span>api<\/span> =<\/span> api;<\/span>
<\/span><\/span>        this<\/span>.<\/span>logging<\/span> =<\/span> api.<\/span>logging<\/span>();<\/span>
<\/span><\/span>    }<\/span>
<\/span><\/span>    
<\/span><\/span>    @Override<\/span>
<\/span><\/span>    public<\/span> void<\/span> handleWebSocketCreated<\/span>(<\/span>WebSocketCreated webSocketCreated)<\/span> {<\/span>
<\/span><\/span>        \/\/ 在这里处理WebSocket连接创建事件
<\/span><\/span><\/span><\/span>        logging.<\/span>logToOutput<\/span>(<\/span>"WebSocket连接已创建: "<\/span> +<\/span> webSocketCreated);<\/span>
<\/span><\/span>    }<\/span>
<\/span><\/span>}<\/span>
<\/span><\/span><\/code><\/pre>3.3 处理WebSocket消息<\/h3>
为了处理WebSocket消息，我们需要注册消息处理器：<\/p>
@Override<\/span>
<\/span><\/span>public<\/span> void<\/span> handleWebSocketCreated<\/span>(<\/span>WebSocketCreated webSocketCreated)<\/span> {<\/span>
<\/span><\/span>    \/\/ 注册二进制消息处理器
<\/span><\/span><\/span><\/span>    webSocketCreated.<\/span>webSocket<\/span>().<\/span>registerBinaryMessageHandler<\/span>(<\/span>new<\/span> BinaryMessageHandler()<\/span> {<\/span>
<\/span><\/span>        @Override<\/span>
<\/span><\/span>        public<\/span> void<\/span> handleBinaryMessage<\/span>(<\/span>BinaryMessage binaryMessage)<\/span> {<\/span>
<\/span><\/span>            \/\/ 处理二进制消息
<\/span><\/span><\/span><\/span>            byte<\/span>[]<\/span> payload =<\/span> binaryMessage.<\/span>payload<\/span>();<\/span>
<\/span><\/span>            \/\/ 修改消息内容
<\/span><\/span><\/span><\/span>            byte<\/span>[]<\/span> modifiedPayload =<\/span> modifyPayload(<\/span>payload);<\/span>
<\/span><\/span>            \/\/ 发送修改后的消息
<\/span><\/span><\/span><\/span>            binaryMessage.<\/span>webSocket<\/span>().<\/span>sendBinaryMessage<\/span>(<\/span>modifiedPayload);<\/span>
<\/span><\/span>        }<\/span>
<\/span><\/span>    });<\/span>
<\/span><\/span>    
<\/span><\/span>    \/\/ 注册文本消息处理器
<\/span><\/span><\/span><\/span>    webSocketCreated.<\/span>webSocket<\/span>().<\/span>registerTextMessageHandler<\/span>(<\/span>new<\/span> TextMessageHandler()<\/span> {<\/span>
<\/span><\/span>        @Override<\/span>
<\/span><\/span>        public<\/span> void<\/span> handleTextMessage<\/span>(<\/span>TextMessage textMessage)<\/span> {<\/span>
<\/span><\/span>            \/\/ 处理文本消息
<\/span><\/span><\/span><\/span>            String payload =<\/span> textMessage.<\/span>payload<\/span>();<\/span>
<\/span><\/span>            \/\/ 修改消息内容
<\/span><\/span><\/span><\/span>            String modifiedPayload =<\/span> modifyPayload(<\/span>payload);<\/span>
<\/span><\/span>            \/\/ 发送修改后的消息
<\/span><\/span><\/span><\/span>            textMessage.<\/span>webSocket<\/span>().<\/span>sendTextMessage<\/span>(<\/span>modifiedPayload);<\/span>
<\/span><\/span>        }<\/span>
<\/span><\/span>    });<\/span>
<\/span><\/span>}<\/span>
<\/span><\/span><\/code><\/pre>3.4 实现消息篡改逻辑<\/h3>
private<\/span> String modifyPayload<\/span>(<\/span>String originalPayload)<\/span> {<\/span>
<\/span><\/span>    \/\/ 示例：修改聊天消息的哈希值
<\/span><\/span><\/span><\/span>    try<\/span> {<\/span>
<\/span><\/span>        JSONObject json =<\/span> new<\/span> JSONObject(<\/span>originalPayload);<\/span>
<\/span><\/span>        String content =<\/span> json.<\/span>getString<\/span>(<\/span>"content"<\/span>);<\/span>
<\/span><\/span>        \/\/ 计算新的哈希值
<\/span><\/span><\/span><\/span>        String newHash =<\/span> calculateSHA256(<\/span>content);<\/span>
<\/span><\/span>        \/\/ 更新哈希值
<\/span><\/span><\/span><\/span>        json.<\/span>put<\/span>(<\/span>"hash"<\/span>,<\/span> newHash);<\/span>
<\/span><\/span>        return<\/span> json.<\/span>toString<\/span>();<\/span>
<\/span><\/span>    }<\/span> catch<\/span> (<\/span>JSONException e)<\/span> {<\/span>
<\/span><\/span>        logging.<\/span>logToError<\/span>(<\/span>"解析JSON失败: "<\/span> +<\/span> e.<\/span>getMessage<\/span>());<\/span>
<\/span><\/span>        return<\/span> originalPayload;<\/span>
<\/span><\/span>    }<\/span>
<\/span><\/span>}<\/span>
<\/span><\/span>
<\/span><\/span>private<\/span> byte<\/span>[]<\/span> modifyPayload<\/span>(<\/span>byte<\/span>[]<\/span> originalPayload)<\/span> {<\/span>
<\/span><\/span>    \/\/ 处理二进制消息的修改逻辑
<\/span><\/span><\/span><\/span>    \/\/ 这里可以根据实际需求实现
<\/span><\/span><\/span><\/span>    return<\/span> originalPayload;<\/span>
<\/span><\/span>}<\/span>
<\/span><\/span>
<\/span><\/span>private<\/span> String calculateSHA256<\/span>(<\/span>String input)<\/span> {<\/span>
<\/span><\/span>    try<\/span> {<\/span>
<\/span><\/span>        MessageDigest digest =<\/span> MessageDigest.<\/span>getInstance<\/span>(<\/span>"SHA-256"<\/span>);<\/span>
<\/span><\/span>        byte<\/span>[]<\/span> hashBytes =<\/span> digest.<\/span>digest<\/span>(<\/span>input.<\/span>getBytes<\/span>(<\/span>StandardCharsets.<\/span>UTF_8<\/span>));<\/span>
<\/span><\/span>        return<\/span> bytesToHex(<\/span>hashBytes);<\/span>
<\/span><\/span>    }<\/span> catch<\/span> (<\/span>NoSuchAlgorithmException e)<\/span> {<\/span>
<\/span><\/span>        logging.<\/span>logToError<\/span>(<\/span>"计算哈希失败: "<\/span> +<\/span> e.<\/span>getMessage<\/span>());<\/span>
<\/span><\/span>        return<\/span> ""<\/span>;<\/span>
<\/span><\/span>    }<\/span>
<\/span><\/span>}<\/span>
<\/span><\/span>
<\/span><\/span>private<\/span> static<\/span> String bytesToHex<\/span>(<\/span>byte<\/span>[]<\/span> bytes)<\/span> {<\/span>
<\/span><\/span>    StringBuilder hexString =<\/span> new<\/span> StringBuilder();<\/span>
<\/span><\/span>    for<\/span> (<\/span>byte<\/span> b :<\/span> bytes)<\/span> {<\/span>
<\/span><\/span>        String hex =<\/span> Integer.<\/span>toHexString<\/span>(<\/span>0xff<\/span> &<\/span> b);<\/span>
<\/span><\/span>        if<\/span> (<\/span>hex.<\/span>length<\/span>()<\/span> ==<\/span> 1<\/span>)<\/span> hexString.<\/span>append<\/span>(<\/span>'0'<\/span>);<\/span>
<\/span><\/span>        hexString.<\/span>append<\/span>(<\/span>hex);<\/span>
<\/span><\/span>    }<\/span>
<\/span><\/span>    return<\/span> hexString.<\/span>toString<\/span>();<\/span>
<\/span><\/span>}<\/span>
<\/span><\/span><\/code><\/pre>4. 关键API说明<\/h2>
4.1 WebSocket相关API<\/h3>

registerWebSocketCreatedHandler()<\/code> - 注册WebSocket连接创建时的处理器<\/li>
WebSocket<\/code>接口提供的方法：

registerBinaryMessageHandler()<\/code> - 注册二进制消息处理器<\/li>
registerTextMessageHandler()<\/code> - 注册文本消息处理器<\/li>
sendBinaryMessage()<\/code> - 发送二进制消息<\/li>
sendTextMessage()<\/code> - 发送文本消息<\/li>
<\/ul>
<\/li>
<\/ol>
4.2 消息处理接口<\/h3>

WebSocketCreatedHandler<\/code> - WebSocket连接创建时的处理接口<\/li>
BinaryMessageHandler<\/code> - 二进制消息处理接口<\/li>
TextMessageHandler<\/code> - 文本消息处理接口<\/li>
<\/ol>
5. 实际应用场景<\/h2>
本插件可用于以下场景：<\/p>

绕过WebSocket消息的签名校验<\/li>
修改实时聊天应用的消息内容<\/li>
篡改游戏中的实时数据<\/li>
测试WebSocket协议的安全性<\/li>
<\/ol>
6. 注意事项<\/h2>

确保正确处理二进制和文本两种消息类型<\/li>
修改消息时要保持协议格式的一致性<\/li>
注意异常处理，避免插件崩溃<\/li>
考虑性能影响，避免在消息处理中执行耗时操作<\/li>
<\/ol>
7. 总结<\/h2>
通过本教程，我们学习了如何开发Burp Suite插件来拦截和篡改WebSocket报文。关键点包括：<\/p>

注册WebSocket连接创建处理器<\/li>
实现二进制和文本消息处理器<\/li>
修改消息内容并重新计算签名<\/li>
发送修改后的消息<\/li>
<\/ol>
这种技术可以用于安全测试，帮助发现WebSocket协议实现中的安全漏洞。<\/p>