** Command to list all infected files:
grep -lr --include=*.php "eval(base64_decode" /path/to/webroot
grep -lr --include=*.php "eval" .
grep -lr --include=*.php "base64" .
grep -lr --include=*.php "eval(base64_decode" /path/to/webroot | xargs sed -i.bak 's/<?php eval(base64_decode[^;]*;/<?php\n/g'