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扫描器需要实现的功能思维导图

Python实现SQL注入检测插件实例代码

爬虫编写思路

首先需要开发一个爬虫用于收集网站的链接,爬虫需要记录已经爬取的链接和待爬取的链接,并且去重,用 Python 的set()就可以解决,大概流程是:

  • 输入 URL
  • 下载解析出 URL
  • URL 去重,判断是否为本站
  • 加入到待爬列表
  • 重复循环

SQL 判断思路

  • 通过在 URL 后面加上AND %d=%d或者OR NOT (%d>%d)
  • %d后面的数字是随机可变的
  • 然后搜索网页中特殊关键词,比如:

MySQL 中是 SQL syntax.*MySQL
Microsoft SQL Server 是 Warning.*mssql_
Microsoft Access 是 Microsoft Access Driver
Oracle 是 Oracle error
IBM DB2 是 DB2 SQL error
SQLite 是 SQLite.Exception
...

通过这些关键词就可以判断出所用的数据库

  • 还需要判断一下 waf 之类的东西,有这种东西就直接停止。简单的方法就是用特定的 URL 访问,如果出现了像IP banned,fierwall之类的关键词,可以判断出是waf。具体的正则表达式是("color: #ff0000">请安装这些库

    pip install requests
    pip install beautifulsoup4

    实验环境是 Linux,创建一个Code目录,在其中创建一个work文件夹,将其作为工作目录

    目录结构

    /w8ay.py  // 项目启动主文件
    /lib/core // 核心文件存放目录
    /lib/core/config.py // 配置文件
    /script   // 插件存放
    /exp      // exp和poc存放

    步骤

    SQL 检测脚本编写

    DBMS_ERRORS = {
      'MySQL': (r"SQL syntax.*MySQL", r"Warning.*mysql_.*", r"valid MySQL result", r"MySqlClient\."),
      "PostgreSQL": (r"PostgreSQL.*ERROR", r"Warning.*\Wpg_.*", r"valid PostgreSQL result", r"Npgsql\."),
      "Microsoft SQL Server": (r"Driver.* SQL[\-\_\ ]*Server", r"OLE DB.* SQL Server", r"(\W|\A)SQL Server.*Driver", r"Warning.*mssql_.*", r"(\W|\A)SQL Server.*[0-9a-fA-F]{8}", r"(", r"("),
      "Microsoft Access": (r"Microsoft Access Driver", r"JET Database Engine", r"Access Database Engine"),
      "Oracle": (r"\bORA-[0-9][0-9][0-9][0-9]", r"Oracle error", r"Oracle.*Driver", r"Warning.*\Woci_.*", r"Warning.*\Wora_.*"),
      "IBM DB2": (r"CLI Driver.*DB2", r"DB2 SQL error", r"\bdb2_\w+\("),
      "SQLite": (r"SQLite/JDBCDriver", r"SQLite.Exception", r"System.Data.SQLite.SQLiteException", r"Warning.*sqlite_.*", r"Warning.*SQLite3::", r"\[SQLITE_ERROR\]"),
      "Sybase": (r"(", r"Sybase message", r"Sybase.*Server message.*"),
    }

    通过正则表达式就可以判断出是哪个数据库了

    for (dbms, regex) in ((dbms, regex) for dbms in DBMS_ERRORS for regex in DBMS_ERRORS[dbms]):
      if (re.search(regex,_content)):
        return True

    下面是我们测试语句的payload

    BOOLEAN_TESTS = (" AND %d=%d", " OR NOT (%d=%d)")

    用报错语句返回正确的内容和错误的内容进行对比

    for test_payload in BOOLEAN_TESTS:
      # Right Page
      RANDINT = random.randint(1, 255)
      _url = url + test_payload % (RANDINT, RANDINT)
      content["true"] = Downloader.get(_url)
      _url = url + test_payload % (RANDINT, RANDINT + 1)
      content["false"] = Downloader.get(_url)
      if content["origin"] == content["true"] != content["false"]:
        return "sql found: %" % url

    这句

    content["origin"] == content["true"] != content["false"]

    意思就是当原始网页等于正确的网页不等于错误的网页内容时,就可以判定这个地址存在注入漏洞

    完整代码:

    import re, random
    from lib.core import Download
    def sqlcheck(url):
      if (not url.find("")): # Pseudo-static page
        return false;
      Downloader = Download.Downloader()
      BOOLEAN_TESTS = (" AND %d=%d", " OR NOT (%d=%d)")
      DBMS_ERRORS = {
        # regular expressions used for DBMS recognition based on error message response
        "MySQL": (r"SQL syntax.*MySQL", r"Warning.*mysql_.*", r"valid MySQL result", r"MySqlClient\."),
        "PostgreSQL": (r"PostgreSQL.*ERROR", r"Warning.*\Wpg_.*", r"valid PostgreSQL result", r"Npgsql\."),
        "Microsoft SQL Server": (r"Driver.* SQL[\-\_\ ]*Server", r"OLE DB.* SQL Server", r"(\W|\A)SQL Server.*Driver", r"Warning.*mssql_.*", r"(\W|\A)SQL Server.*[0-9a-fA-F]{8}", r"(", r"("),
        "Microsoft Access": (r"Microsoft Access Driver", r"JET Database Engine", r"Access Database Engine"),
        "Oracle": (r"\bORA-[0-9][0-9][0-9][0-9]", r"Oracle error", r"Oracle.*Driver", r"Warning.*\Woci_.*", r"Warning.*\Wora_.*"),
        "IBM DB2": (r"CLI Driver.*DB2", r"DB2 SQL error", r"\bdb2_\w+\("),
        "SQLite": (r"SQLite/JDBCDriver", r"SQLite.Exception", r"System.Data.SQLite.SQLiteException", r"Warning.*sqlite_.*", r"Warning.*SQLite3::", r"\[SQLITE_ERROR\]"),
        "Sybase": (r"(", r"Sybase message", r"Sybase.*Server message.*"),
      }
      _url = url + "%29%28%22%27"
      _content = Downloader.get(_url)
      for (dbms, regex) in ((dbms, regex) for dbms in DBMS_ERRORS for regex in DBMS_ERRORS[dbms]):
        if (re.search(regex,_content)):
          return True
      content = {}
      content['origin'] = Downloader.get(_url)
      for test_payload in BOOLEAN_TESTS:
        # Right Page
        RANDINT = random.randint(1, 255)
        _url = url + test_payload % (RANDINT, RANDINT)
        content["true"] = Downloader.get(_url)
        _url = url + test_payload % (RANDINT, RANDINT + 1)
        content["false"] = Downloader.get(_url)
        if content["origin"] == content["true"] != content["false"]:
          return "sql found: %" % url

    将这个文件命名为sqlcheck.py,放在/script目录中。代码的第 4 行作用是查找 URL 是否包含"color: #ff0000">爬虫的编写

    爬虫的思路上面讲过了,先完成 URL 的管理,我们单独将它作为一个类,文件保存在/lib/core/UrlManager.py

    #-*- coding:utf-8 -*-
    
    class UrlManager(object):
      def __init__(self):
        self.new_urls = set()
        self.old_urls = set()
        
      def add_new_url(self, url):
        if url is None:
          return
        if url not in self.new_urls and url not in self.old_urls:
          self.new_urls.add(url)
       
      def add_new_urls(self, urls):
        if urls is None or len(urls) == 0:
          return
        for url in urls:
          self.add_new_url(url)
        
      def has_new_url(self):
        return len(self.new_urls) != 0
       
      def get_new_url(self):
        new_url = self.new_urls.pop()
        self.old_urls.add(new_url)
        return new_url

    为了方便,我们也将下载功能单独作为一个类使用,文件保存在lib/core/Downloader.py

    #-*- coding:utf-8 -*-
    import requests
    
    class Downloader(object):
      def get(self, url):
        r = requests.get(url, timeout = 10)
        if r.status_code != 200:
          return None
        _str = r.text
        return _str
      
      def post(self, url, data):
        r = requests.post(url, data)
        _str = r.text
        return _str
      
      def download(self, url, htmls):
        if url is None:
          return None
        _str = {}
        _str["url"] = url
        try:
          r = requests.get(url, timeout = 10)
          if r.status_code != 200:
            return None
          _str["html"] = r.text
        except Exception as e:
          return None
        htmls.append(_str)

    特别说明,因为我们要写的爬虫是多线程的,所以类中有个download方法是专门为多线程下载专用的

    在lib/core/Spider.py中编写爬虫

    #-*- coding:utf-8 -*-
    
    from lib.core import Downloader, UrlManager
    import threading
    from urllib import parse
    from urllib.parse import urljoin
    from bs4 import BeautifulSoup
    
    class SpiderMain(object):
      def __init__(self, root, threadNum):
        self.urls = UrlManager.UrlManager()
        self.download = Downloader.Downloader()
        self.root = root
        self.threadNum = threadNum
      
      def _judge(self, domain, url):
        if (url.find(domain) != -1):
          return True
        return False
      
      def _parse(self, page_url, content):
        if content is None:
          return
        soup = BeautifulSoup(content, 'html.parser')
        _news = self._get_new_urls(page_url, soup)
        return _news
        
      def _get_new_urls(self, page_url, soup):
        new_urls = set()
        links = soup.find_all('a')
        for link in links:
          new_url = link.get('href')
          new_full_url = urljoin(page_url, new_url)
          if (self._judge(self.root, new_full_url)):
            new_urls.add(new_full_url)
        return new_urls
        
      def craw(self):
        self.urls.add_new_url(self.root)
        while self.urls.has_new_url():
          _content = []
          th = []
          for i in list(range(self.threadNum)):
            if self.urls.has_new_url() is False:
              break
            new_url = self.urls.get_new_url()
            
            ## sql check
            try:
              if (sqlcheck.sqlcheck(new_url)):
                print("url:%s sqlcheck is valueable" % new_url)
            except:
              pass
                
            print("craw:" + new_url)
            t = threading.Thread(target = self.download.download, args = (new_url, _content))
            t.start()
            th.append(t)
          for t in th:
            t.join()
          for _str in _content:
            if _str is None:
              continue
            new_urls = self._parse(new_url, _str["html"])
            self.urls.add_new_urls(new_urls)

    爬虫通过调用craw()方法传入一个网址进行爬行,然后采用多线程的方法下载待爬行的网站,下载之后的源码用_parse方法调用BeautifulSoup进行解析,之后将解析出的 URL 列表丢入 URL 管理器,这样循环,最后只要爬完了网页,爬虫就会停止

    threading库可以自定义需要开启的线程数,线程开启后,每个线程会得到一个 url 进行下载,然后线程会阻塞,阻塞完毕后线程放行

    爬虫和 SQL 检查的结合

    在lib/core/Spider.py文件引用一下from script import sqlcheck,在craw()方法中,取出新的 URL 地方调用一下

    ##sql check
    try:
      if(sqlcheck.sqlcheck(new_url)):
        print("url:%s sqlcheck is valueable"%new_url)
    except:
      pass

    用try检测可能出现的异常,绕过它,在文件w8ay.py中进行测试

    #-*- coding:utf-8 -*-
    '''
    Name: w8ayScan
    Author: mathor
    Copyright (c) 2019
    '''
    import sys
    from lib.core.Spider import SpiderMain
    def main():
      root = "https://wmathor.com"
      threadNum = 50
      w8 = SpiderMain(root, threadNum)
      w8.craw()
     
    if __name__ == "__main__":
      main()

    很重要的一点!为了使得lib和script文件夹中的.py文件可以可以被认作是模块,请在lib、lib/core和script文件夹中创建__init__.py文件,文件中什么都不需要写

    总结

    SQL 注入检测通过一些payload使页面出错,判断原始网页,正确网页,错误网页即可检测出是否存在 SQL 注入漏洞
    通过匹配出 sql 报错出来的信息,可以正则判断所用的数据库

    好了,以上就是这篇文章的全部内容了,希望本文的内容对大家的学习或者工作具有一定的参考学习价值,如果有疑问大家可以留言交流,谢谢大家对的支持。

标签:
python防sql注入,python防止sql注入,python编写sql注入

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