SQL Injection - Filter bypass

SQL Injection - Filter bypass (Hard - 80 pts)

After reviewing the entire website, I found that id parameter to show user's information is where we can inject SQL injection.

http://challenge01.root-me.org/web-serveur/ch30/?action=membres&id=

Tip:

Why I know that. If you get used to SQL injection, you will be sensitive with where the information is leaked.

But in this challenge, there are a lot of characters and words are filtered. I will list some I met: or, and, ||, /**/, union, select, join, whitespace, like, =, %0a, %0b, %0c, ',comma(,),...

But with select and union, just upercase is filtered, when I change these words to lowercase, we can bypass.

With these information, my idea is use UNION and SELECT to leak information from table membres. Table name and columns name is provide, you can view source to see:

If don't have above provided information, this challenge will become very difficult because when I test, information_schema.tables, =, like are filtered so we can't leak table name as well as columns name easily.

Okay, back to challenge, because whitespace and many tab character is filter so I will use %09 to replace for whitespace.

Now, our payload will look like:

id=9%09UNION%09SELECT%09pass,1,1,1%09FROM%09membres%09LIMIT%091

But the comma (,) character is filtered, so we can use it to select like below payload.

So we must find a way to change this select query to other query which have the same meaning.

After searching, I found solution:

For example, my query is:

I will rewrite below query use join:

select * from ((select 1)A join (select 2)B join (select 3)C);

But there is a small note that with join word, the upercase is filtered, but lowercase is not, so in your payload, you must to use JOIN.

Final payload:

id=9%09UNION%09SELECT%09*%09FROM%09((SELECT%09pass%09FROM%09membres%09LIMIT%091)A%09JOIN%09(SELECT%092)B%09JOIN%09(SELECT%093)C%09JOIN%09(SELECT%093)D)