Example – SQL Injection MySQL & PHP code: // The next instruction prompts the user is to supply an ID $personID = getIDstringFromUser(); $sqlQuery = "SELECT * FROM Users WHERE userID = " + $personID; What if the user supplies the following string for $personID? The resulting string assigned to sqlQuery is SELECT * FROM Users WHERE userID = _________ What if the user supplies the following string for $personID?
Input Validation – common associated risks ______________ user input controls SQL statements ultimately executed by a database server ______________ user input controls file access location – the “double-dot attack” ______________ user input controls file naming in such a way as to get a program to read, write or delete files that should be protected Denial of Service user input controls causes application to consume excessive resources or simply stop executing due to unacceptable input _______________ user input controls causes the application to reveal confidential information perhaps this information can be used as part of a more sophisticated attack Please check out OWASP
more common associated risks Cross Site Scripting (XSS) user input controls injects HTML or script commands into Web application causing the Web application to breach its security My Javascript Page type your name here >>> Submit var thing = "blah"; function buttonHandler() { var stuff = document.getElementById("userInput").value; document.write(stuff); }
still more common associated risks ______________ user input injects commands, often via meta-characters, that cause a server to perform unintended functions Buffer Overflows user input controls exceeds limits in a way that allows the attacker to control application behavior
Before Mitigation user interface files parameters of externally-invoked methods network sockets/ports URLs (passed to Web servers) cookies network certificates
Mitigation Techniques
Escaping individual characters is a particularly effective way of mitigating XSS. CharacterEquivalent HTML escape “" ## && ‘' (( )) // ;; << >>