What characters have to be escaped to prevent (My)SQL injections?

Question

I'm using MySQL API's function

mysql_real_escape_string()

Based on the documentation, it escapes the following characters:

\0
\n
\r
\
'
"
\Z

Now, I looked into OWASP.org's ESAPI security library and in the Python port it had the following code (http://code.google.com/p/owasp-esapi-python/source/browse/esapi/codecs/mysql.py):

        """
        Encodes a character for MySQL.
        """
        lookup = {
        0x00 : "\\0",
        0x08 : "\\b",
        0x09 : "\\t",
        0x0a : "\\n",
        0x0d : "\\r",
        0x1a : "\\Z",
        0x22 : '\\"',
        0x25 : "\\%",
        0x27 : "\\'",
        0x5c : "\\\\",
        0x5f : "\\_",
        }

Now, I'm wondering whether all those characters are really needed to be escaped. I understand why % and _ are there, they are meta characters in LIKE operator, but I can't simply understand why did they add backspace and tabulator characters (\b \t)? Is there a security issue if you do a query:

SELECT a FROM b WHERE c = '...user input ...';

Where user input contains tabulators or backspace characters?

My question is here: Why did they include \b \t in the ESAPI security library? Are there any situations where you might need to escape those characters?

Answer 1

A guess concerning the backspace character: Imagine I send you an email "Hi, here's the query to update your DB as you wanted" and an attached textfile with

INSERT INTO students VALUES ("Bobby Tables",12,"abc",3.6);

You cat the file, see it's okay, and just pipe the file to MySQL. What you didn't know, however, was that I put

DROP TABLE students;\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b\b

before the INSERT STATEMENT which you didn't see because on console output the backspaces overwrote it. Bamm!

Just a guess, though.

Edit (couldn't resist):

Answer 2

The MySQL manual page for strings says:

• \0   An ASCII NUL (0x00) character.
• \'   A single quote (“'”) character.
• \"   A double quote (“"”) character.
• \b   A backspace character.
• \n   A newline (linefeed) character.
• \r   A carriage return character.
• \t   A tab character.
• \Z   ASCII 26 (Control-Z). See note following the table.
• \\   A backslash (“\”) character.
• \%   A “%” character. See note following the table.
• \_   A “_” character. See note following the table.