Should Backspace and Tab Characters Be Escaped in SQL Injections?

Escaping Special Characters in SQL Injections

To prevent SQL injections, it's crucial to escape specific characters that can manipulate query execution. According to the MySQL API's mysql_real_escape_string() function, these characters should be escaped:

<pre class="brush:php;toolbar:false">0x00 : "\0",
0x08 : "\b",
0x09 : "\t",
0x0a : "\n",
0x0d : "\r",
0x1a : "\Z",
0x22 : '\"',
0x25 : "\%",
0x27 : "\'",
0x5c : "\\",
0x5f : "\_",

\n \r \ ' " \Z

However, the OWASP.org's ESAPI security library for Python goes beyond these characters, including the following in its encoding mechanism:

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

While it's understandable why metacharacters like '%' and '_' should be escaped, the inclusion of backspace ('b') and tabulator ('t') characters raises questions.

Security Concerns with Tabulators and Backspace Characters

Tabulator Character ('t')

A tabulator character (ASCII code 9) moves the cursor to the next tab stop, defined for a particular system. In a SQL query, a tabulator could be used to insert blank spaces or align data. Depending on the tab stop settings, an attacker could potentially modify a query or inject whitespace, leading to unintended behavior.

Backspace Character ('b')

A backspace character (ASCII code 8) moves the cursor one character backward, effectively overwriting it. In a SQL query, a backspace could be used to erase previously entered data, potentially leading to injections or data manipulation.

Example: Backspace Character Exploitation

Consider the following query:

Bobby]dor[p TA[ble[s

If a malicious user inputs a value containing backspace characters, they could potentially erase part of the query, resulting in an unintended behavior. For instance, inserting this input:

SELECT a FROM b WHERE c = 'Bobby';

After the backspaces delete the characters "[dor[p TA[ble[s", the query effectively becomes:

This malicious input could potentially return all rows where c equals 'Bobby,' potentially compromising sensitive information.

Conclusion

While escaping tabulator and backspace characters may not be commonly required, they can be valuable in certain scenarios to prevent SQL injections. By escaping these characters, developers can ensure that malicious users cannot exploit potential vulnerabilities to tamper with or compromise SQL queries.

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