强化 web 攻击神器 Burp Suite (二) — 切换 ip 技能点

前言

上篇文章给 Burp Suite 添加验证码识别技能点，对于现代化的渗透测试神器来说，自动化切换 ip 也是必备技能，本文通过动态设置 HTTP 代理来完善此功能。

快速开发

原理分析

对于 HTTP 代理，HTTP 客户端向代理发送请求报文，代理服务器需要正确地处理请求和连接（例如正确处理 Connection: keep-alive），同时向服务器发送请求，并将收到的响应转发给客户端。

图片来源:《HTTP 权威指南》

原理较为简单，具体看数据包对比
正常访问

http 流

GET / HTTP/1.1
Host: myip.ipip.net
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:69.0) Gecko/20100101 Firefox/69.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2
Accept-Encoding: gzip, deflate
Connection: keep-alive
Upgrade-Insecure-Requests: 1
Cache-Control: max-age=0

HTTP/1.1 200 OK
Date: Mon, 01 Apr 2020 16:58:35 GMT
Content-Type: text/plain; charset=utf-8
Content-Length: 67
Connection: keep-alive
...... IP...113.*.*.*  .................. ...... ......  ......

代理访问
HTTP 代理 180.143.244.66:18637

http 流

GET http://myip.ipip.net/ HTTP/1.1
Host: myip.ipip.net
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:69.0) Gecko/20100101 Firefox/69.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2
Accept-Encoding: gzip, deflate
Connection: keep-alive
Upgrade-Insecure-Requests: 1
Cache-Control: max-age=0

HTTP/1.1 200 OK
Date: Mon, 01 Apr 2020 17:18:45 GMT
Content-Type: text/plain; charset=utf-8
Content-Length: 69
Connection: close

...... IP...180.143.244.66  .................. ...... ......  ......

可以看到正常访问和代理访问在数据层就是请求路径和目标不同。使用代理就是把数据带上目标信息先发送到代理服务器，要在 Burp Suite 中实现代理功能，动态修改请求目标和请求 header 即可。

代码编写

参考官方文档，修改 HTTP 请求，需要在脚本中实例化 IHttpListener 类并重写 processHttpMessage 方法。

HTTP_PROXY={
    'ip':'14.118.163.95',
    'port':19048
    }
class BurpExtender(IBurpExtender, IHttpListener):

    def registerExtenderCallbacks(self, callbacks):

        self._callbacks = callbacks
        self._helpers = callbacks.getHelpers()
        callbacks.setExtensionName("IP switch")
        callbacks.registerHttpListener(self)

    def processHttpMessage(self, toolFlag, messageIsRequest, messageInfo):
    
        # 只处理请求
        if not messageIsRequest:
            return

        httpService = messageInfo.getHttpService()
        # 修改请求目标为代理中转
        messageInfo.setHttpService(
                        self.helpers.buildHttpService(
                            HTTP_PROXY['ip'],
                            HTTP_PROXY['port'], True
                        )
                    )
  
        requestInfo = self.helpers.analyzeRequest(messageInfo)
        new_headers = requestInfo.headers
        # 修改 http 头
        req_head = new_headers[0]
        new_headers[0] = re.sub('\/'," http://myip.ipip.net/",req_head)
        body = messageInfo.request[requestInfo.getBodyOffset():len(messageInfo.request)]
        messageInfo.request = self.helpers.buildHttpMessage(
                            new_headers,
                            body)