PHP MySQL injection example?

 

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  • How can I prevent SQL injection in PHP? 28 answers

    • One of the most common examples is this query: 

    ' or '1'='1

    If you enter this as the username and password into some unsanitized login input the query changes like so: 

    Original: SELECT * FROM USERS WHERE USER='' AND PASS='';
Modified: SELECT * FROM USERS WHERE USER='' or '1'='1' AND PASS='' or '1'='1';

    This causes each thing its looking for to be true, as 1 will always equal 1. Problem with this method is it does not allow the selection of a particular user. Doing so you need to make it ignore the AND statement by commenting it out as seen in other examples.

    If the value of username is: 

     $_POST['user'] = "1' OR 1 LIMIT 1; --";

    Then the mysql query becomes: 

    select * 
from zend_adminlist 
where user_name = '1' OR 1 LIMIT 1; --' and password = '$pass'
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