ECCouncil 312-50v12 Practice Test - Questions Answers, Page 58

The most effective evasion technique to bypass the IDS signature detection while performing a SQL Injection attack is to leverage string concatenation to break identifiable keywords. This technique involves splitting SQL keywords or operators into smaller parts and joining them with string concatenation operators, such as '+' or '||'. This way, the SQL query can still be executed by the database engine, but the IDS cannot recognize the keywords or operators as malicious, as they are hidden within strings.For example, the hacker could replace the keyword 'OR' with 'O'||'R' or 'O'+'R' in the SQL query, and the IDS would not be able to match the signature of a typical SQL injection pattern12.

The other options are not as effective as option D for the following reasons:

A) Implement case variation by altering the case of SQL statements: This option is not effective because most SQL engines and IDS systems are case-insensitive, meaning that they treat SQL keywords and operators the same regardless of their case.Therefore, altering the case of SQL statements would not help evade the IDS signature detection, as the IDS would still be able to match the signature of a typical SQL injection pattern3.

B) Employ IP fragmentation to obscure the attack payload: This option is not applicable because IP fragmentation is a network-level technique that splits IP packets into smaller fragments to fit the maximum transmission unit (MTU) of the network.IP fragmentation does not affect the content or structure of the SQL query, and it does not help evade the IDS signature detection, as the IDS would still be able to reassemble the fragments and match the signature of a typical SQL injection pattern4.

C) Use Hex encoding to represent the SQL query string: This option is not feasible because Hex encoding is a method of representing binary data in hexadecimal format, such as '0x41' for 'A'. Hex encoding does not work for SQL queries, as the SQL engine would not be able to interpret the hexadecimal values as valid SQL syntax. Moreover, Hex encoding would not help evade the IDS signature detection, as the IDS would still be able to decode the hexadecimal values and match the signature of a typical SQL injection pattern.

1: SQL Injection Evasion Detection - F5

2: Mastering SQL Injection with SQLmap: A Comprehensive Evasion Techniques Cheatsheet

3: SQL Injection Prevention - OWASP Cheat Sheet Series

4: IP Fragmentation - an overview | ScienceDirect Topics

: Hex Encoding - an overview | ScienceDirect Topics

SQL Injection is a type of attack that exploits a vulnerability in a web application that uses a SQL database. The attacker injects malicious SQL code into the user input, such as a login form, that is then executed by the database server. This can allow the attacker to access, modify, or delete data, or execute commands on the database server.

The 'UNION' SQL keyword is often used in SQL Injection attacks to combine the results of two or more SELECT statements into a single result set. This can allow the attacker to retrieve additional data from other tables or columns that are not intended to be displayed by the application. For example, if the application uses the following query to check the user credentials:

SELECT * FROM users WHERE username = '$username' AND password = '$password'

The attacker can inject a 'UNION' statement to append another query, such as:

' OR 1 = 1 UNION SELECT * FROM credit_cards --

This will result in the following query being executed by the database server:

SELECT * FROM users WHERE username = " OR 1 = 1 UNION SELECT * FROM credit_cards --' AND password = '$password'

The first part of the query will always return true, and the second part of the query will return the data from the credit_cards table. The '--' symbol is a comment that will ignore the rest of the query. The attacker can then see the credit card information in the application's response.

However, some web applications implement security measures to prevent SQL Injection attacks, such as filtering special characters in user inputs. Special characters are symbols that have a special meaning in SQL, such as quotes, semicolons, dashes, etc. By filtering or escaping these characters, the application can prevent the attacker from injecting malicious SQL code. For example, if the application replaces single quotes with two single quotes, the previous injection attempt will fail, as the query will become:

SELECT * FROM users WHERE username = "" OR 1 = 1 UNION SELECT * FROM credit_cards --" AND password = '$password'

This will result in a syntax error, as the query is not valid SQL.

In this challenging environment, if the hacker still intends to exploit this SQL Injection vulnerability, the strategy that he is most likely to employ is to bypass the special character filter by encoding his malicious input. Encoding is a process of transforming data into a different format, such as hexadecimal, base64, URL, etc. By encoding his input, the hacker can avoid the filter and still inject malicious SQL code. For example, if the hacker encodes his input using URL encoding, the previous injection attempt will become:

%27%20OR%201%20%3D%201%20UNION%20SELECT%20*%20FROM%20credit_cards%20--

This will result in the following query being executed by the database server, after the application decodes the input:

SELECT * FROM users WHERE username = " OR 1 = 1 UNION SELECT * FROM credit_cards --' AND password = '$password'

This will succeed in returning the credit card information, as the filter will not detect the special characters in the encoded input.

Therefore, the hacker is most likely to employ the strategy of bypassing the special character filter by encoding his malicious input, which could potentially enable him to successfully inject damaging SQL queries.

SQL Injection | OWASP Foundation

SQL Injection Union Attacks

SQL Injection Bypassing WAF