$re = '/https?.*?\.ru.*?worm/m';
$str = 'http://www.malwarecheap.ru/files/worm.exe
https://tarnacop.ro/dl/worm
ftp://pwned.ru/exploits/worm.zip';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php