gaspersic/freeCodeCamp
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Added explanation on the -- (#22343)

Browse Source 
Added explanations on using `--` in SQL to comment out unwanted trailing characters.

Payload should not have a `'` as numbers should not be wrapped by quotes (source: https://www.w3schools.com/sql/sql_where.asp ) The previous payload would have an extra closing quote in the SQL query.
This commit is contained in:
Bearz314
2018-11-22 08:31:47 +11:00
committed by Christopher McCormack
parent 7588d6693d
commit aae77a7890
1 changed files with 3 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

4
guide/english/php/security/sql-injection/index.md
View File

@ -39,7 +39,9 @@ $conn->close();
SELECT email FROM users WHERE id = `$input`;
```
So with the above the input is not type casted (I.e. casting the input with (int) so only a number is allowed) nor escaped allowing someone to perform an SQL Injection attack - for example the URL `getemailbyuserid.php?id=1'; My Query Here-- -` would allow you to run arbitrary SQL queries with little effort.
So with the above the input is not type casted (I.e. casting the input with `(int)` so only a number is allowed) nor escaped allowing someone to perform an SQL Injection attack - for example the URL `getemailbyuserid.php?id=1; My Query Here--` would allow you to run arbitrary SQL queries with little effort.
As the SQL code is a string which can be controlled by an attacker, the `id` variable in the example above effectively becomes `1; My Query Here--`. The `$sql` string thus becomes `SELECT email FROM users WHERE id =1; My Query Here--`. You can see that arbitrary queries can be appended to the original query. The double-dash `--` comments out any trailing characters which can cause an issue with the payload, like closing quotes if available.
### Defending your website from sql injection attacks in PHP
There are a few approaches to defend your website from SQL Injection Attacks. These approaches are Whitelisting, Type Casting, and Character Escaping