SQL Injection: Unterschied zwischen den Versionen
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=Webfrontend= | =Webfrontend= | ||
[[Datei:Sql-injection-1.png]] | [[Datei:Sql-injection-1.png]] | ||
+ | ==Sicher== | ||
+ | <pre> | ||
+ | $search = mysqli_real_escape_string($link, $_POST['search']); | ||
+ | $sql = "SELECT * FROM users WHERE username='$search'"; | ||
+ | $result = mysqli_query($link, $sql); | ||
+ | </pre> |
Version vom 15. Juni 2021, 19:17 Uhr
Vorüberlegung
Verhaltensweise einer SQL Abfrage
- Normale Abfrage
- MariaDB [sql_injections]> select * from users where username = 'rudi.burkart';
+------+--------------+----------+ | id | username | password | +------+--------------+----------+ | 2 | rudi.burkart | secret | +------+--------------+----------+ 1 row in set (0.000 sec)
- Oder Verknüpfung
- MariaDB [sql_injections]> select * from users where username = 'rudi.burkart' or username = 'hans.will';
+------+--------------+----------+ | id | username | password | +------+--------------+----------+ | 2 | rudi.burkart | secret | | 1 | hans.will | geheim | +------+--------------+----------+ 2 rows in set (0.000 sec)
PHP Code
Unsicher
$search = $_POST['search']; $sql = "SELECT * FROM users WHERE username='$search'"; $result = mysqli_query($link, $sql);
- Diese Eingabe bewirkt nun
- folgende Sql Abfrage
- MariaDB [sql_injections]> select * from users where username = or '1' = '1';
+------+---------------+-------------+ | id | username | password | +------+---------------+-------------+ | 2 | rudi.burkart | secret | | 3 | erwin.lehmann | weisniemand | | 1 | hans.will | geheim | +------+---------------+-------------+ 3 rows in set (0.000 sec)
- Da '1' = '1" werden alle Datensätze angezeigt
Webfrontend
Sicher
$search = mysqli_real_escape_string($link, $_POST['search']); $sql = "SELECT * FROM users WHERE username='$search'"; $result = mysqli_query($link, $sql);