![]() ![]() ![]() This goes for SQL statements, or anything you would call any sort of "eval" function on. [ "No discussion of escaping is complete without telling everyone that you should basically never use external input to generate interpreted code. ![]() Of course a potential attacker could simply modify their parameters to target specific users of interest: So an attacker might be able to log in as any account, but not necessarily with any control over which account it is. There's an interesting quirk in the example #2 about SQL injection: AND takes priority over OR, so the injected query actually executes as WHERE (user='aidan' AND password='') OR ''='', so instead of returning a database record corresponding to an arbitrary username (in this case 'aidan'), it would actually return ALL database records. This is because that user-provided data will often become part of some generated HTML, and you want to ensure that the user provided data isn't going to cause security problems in the browser. That's why this is a general best practice and not something specific to PHP and why you should REALLY adopt it.Īlso, you should still do some kind of validation of the data provided by users, even when using parametric prepared statements. So, no language is immune to this problem. This is how GitHub was hacked at one point. If the mapping produces no value, you know that something is wrong with the user provided data.įailing to follow this has been the cause of a number of SQL-injection problems in the Ruby On Rails framework, even though it uses parametric prepared statements. Instead, you should parse out the portion of the $_SERVER value that you want, and map that through some kind of function or associative array to a non-user provided value. So, for example, if you are building up a little framework and want to do an insert to a table based on the request URI, it's in your best interest to not take the $_SERVER value (or any part of it) and directly concatenate that with your query. Any user-provided data should be passed through as parameters to the statement after it has been prepared. What it means is that you should never use user-provided data to generate those statements. NB: This doesn't mean you should never generate dynamic SQL statements. You should use mysqli's prepare() function ( ) to execute a statement that looks like this: It means instead of building a SQL statement like this: ![]() Honestly, using user provided data to compose SQL statements should be considered professional negligence and you should be held accountable by your employer or client for not using parametric prepared statements. So, instead of using this terribly broken function, use parametric prepared statements instead. No discussion of escaping is complete without telling everyone that you should basically never use external input to generate interpreted code. Getting Started Introduction A simple tutorial Language Reference Basic syntax Types Variables Constants Expressions Operators Control Structures Functions Classes and Objects Namespaces Enumerations Errors Exceptions Fibers Generators Attributes References Explained Predefined Variables Predefined Exceptions Predefined Interfaces and Classes Predefined Attributes Context options and parameters Supported Protocols and Wrappers Security Introduction General considerations Installed as CGI binary Installed as an Apache module Session Security Filesystem Security Database Security Error Reporting User Submitted Data Hiding PHP Keeping Current Features HTTP authentication with PHP Cookies Sessions Dealing with XForms Handling file uploads Using remote files Connection handling Persistent Database Connections Command line usage Garbage Collection DTrace Dynamic Tracing Function Reference Affecting PHP's Behaviour Audio Formats Manipulation Authentication Services Command Line Specific Extensions Compression and Archive Extensions Cryptography Extensions Database Extensions Date and Time Related Extensions File System Related Extensions Human Language and Character Encoding Support Image Processing and Generation Mail Related Extensions Mathematical Extensions Non-Text MIME Output Process Control Extensions Other Basic Extensions Other Services Search Engine Extensions Server Specific Extensions Session Extensions Text Processing Variable and Type Related Extensions Web Services Windows Only Extensions XML Manipulation GUI Extensions Keyboard Shortcuts ? This help j Next menu item k Previous menu item g p Previous man page g n Next man page G Scroll to bottom g g Scroll to top g h Goto homepage g s Goto search ![]()
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