ZendFramework1 Potential SQL injection in the ORDER implementation of Zend_Db_Select

Summary

The implementation of the ORDER BY SQL statement in Zend_Db_Select of Zend Framework 1 contains a potential SQL injection when the query string passed contains parentheses. For instance, the following code is affected by this issue: ``` $db = Zend_Db::factory( /* options here */ ); $select = $db->select() ->from(array('p' => 'products')) ->order('MD5(1); drop table products'); echo $select; ``` This code produce the string: ``` SELECT "p".* FROM "products" AS "p" ORDER BY MD5(1);drop table products ASC ``` instead of the correct one: ``` SELECT "p".* FROM "products" AS "p" ORDER BY "MD5(1);drop table products" ASC ``` The SQL injection occurs because we create a new Zend_Db_Expr() object, in presence of parentheses, passing directly the value without any filter on the string.