The PHP Programmer’s Guide to Secure Code
Abstract : Security threats against computer systems are a big problem today which also includes PHP made applications. The report is focused on protection with the help of code and not how you protect a web server. Its purpose is not to educate the readers of the thesis how to make a PHP application, the purpose is how to program a safer PHP application. The thesis contains information about common security threats against PHP scripts. It contains in most cases examples of what an attack can look like and how a protection for that example can be achieved. We have tested all code examples if they work by installing our own server with the configurations according to the delimitations of the thesis and putting up small PHP applications, which we have attacked and then protected. The contents and result of this thesis can benefit developers that use PHP as a programming language for creating web applications, by giving them information about common threats and protection.
? The more difficult aspects of applied crypto, such as key management, overall cryptographic architecture design, tiering, and trust issues in complex software. Existing crypto hardware, such as a Hardware Security Module (HSM) solutions, can make your job easier.
? Use existing secure framework features rather than using new tools, such as third-party libraries.
? For accessing the information about the uploaded files, two methods exist. The current method is relatively safe. On the other hand there is also a legacy method that is dangerous and should not be used anymore.
? Other databases that do not allow to set default access credentials via php.ini directives a similar solution exists.
? We are not only describing and discussing the problems of different PHP vulnerabilities, we are also testing and verifying the different vulnerabilities found.
? To present the entire script in all cases would be too extensive, but we will present enough to give a general understanding of the problem areas and their solution.
? The purpose of breaking into a system is to steal or destroy data of the system or in other ways cause problems.
? The core problem is that if the script trusts external data as it is, attackers could take advantage of this and send bad data.
• Keep various audit and transaction logs separate for both security and auditing purposes.
• The features used for this purpose do not need to be unique. The idea is simply to introduce new information items in order to raise the bar for an attacker.
• Chances are that the library functions are reviewed by many people and that they contain less errors than a custom function that serves the same purpose.
• So using the .php ending for include files is only an option if include files are used for classic library purposes.
? The web programming language PHP is used by a lot of developers today, which means that a lot of web applications are made in PHP.
? Cross site scripting, or short XSS, is a threat against web applications. An XSS attack takes advantage of a PHP script’s trust towards external data.
? It takes advantage of applications that trust their users. The attacker uses this trust for his/her purposes.
? If a web shop is not protected and its commands for ordering are handled by the get method, as the forum example, the attacker could take advantage of a membership of a customer and order merchandise to the customer by the customer.
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