In short: PHP has a tendency to be vulnerable-as-a-default, the barrier to entry is so low that every noob who barely just learned HTML can already begin writing dangerous code, even the largest web apps in PHP have gaping security holes, and I consider PHP itself to be just an elaborate content management system more than a real programming language.
To break down each of those points:
The last time I made a solid effort to learn to code in PHP, I came to realize that the default php.ini on my system had some rather stupid options turned on by default. For instance, the
include() method would be allowed to include PHP code from a remote URL beginning with "http://". It's things like this that make PHP insecure as a default. I now have learned to carefully prune through my php.ini before installing any PHP web apps on a new server just to make sure no stupid defaults are enabled that will leave my server vulnerable.
The barrier to entry is so low in PHP that people who have no business writing program code are given the tools to do so. A good friend of mine does freelance web security consulting and says that a very good majority of PHP-powered sites he's come across have been vulnerable to SQL injection, and attributes this to the fact that many PHP tutorial sites don't mention SQL injection when they get to the chapter about databases. They'll recommend that you just interpolate variables directly into your SQL queries.
Case in point: the very first result for Googling "php mysql tutorial" that isn't from php.net is this link: PHP/MySQL Tutorial - Part 1. When this tutorial gets to the insertion part, it recommends you just formulate a query like this:
SELECT * FROM contacts WHERE id='$id'
SELECT * FROM tablename WHERE fieldname LIKE '%$string%'
Coding practices like this will leave you a lot of pain to come in the future. I'm not a PHP tutorial site so I won't even bother to explain how to avoid SQL injection in PHP. I won't use any of your code on my server so your own stupidity will be your own downfall, and it won't be my problem.
As an example of a large PHP web app having gaping wide security holes, just read about how my server got hacked through phpMyAdmin. In short, there was a PHP script in the "setup" folder that ended with a .inc.php file extension (indicating it was meant to be included and not requested directly over HTTP), and it would execute system commands using data provided by the query string. I've ranted about how badly I hate PHP even more because of this on that blog post. And that in Perl, this sort of thing wouldn't even happen, because an included script would have to go out of its way to read the query string; it wouldn't just use the query string "by accident" like PHP scripts are apt to do.
Besides SQL injection being one of THE most popular attack vectors for anything written in PHP, but if I ever hear about a PHP exploit besides that it almost invariable is this: somebody fooled a PHP script into including a PHP source from a remote domain. Example:
Your site has URLs that look like this,
And your "index.php" there will take "p=home" and include "home.php" to show you the home page. Okay, what about this then?
And your index.php includes pwned.php from that malicious looking URL and now a hacker can run literally any code they like on your server. I've witnessed sites being pwned by this more times than I can care to count, oftentimes because the php.ini was misconfigured as a default.
Moving on to the last point, I don't consider PHP to be a real programming language. It is more like a web framework, like Drupal or MovableType or Catalyst, that is packed full of tools specifically geared towards the web. PHP has thousands of built in functions for everything a web app could imagine needing to do, from MySQL to CGI. The web page "PHP in contast to Perl" sums up all of the problems with PHP's vast array of global functions. They're inconsistently named and many of them do extremely similar things.
Contrast that to Perl, where the core language only provides the functions you would expect from a real programming language, and to do anything "cool" you'll need to include modules which provide you with more functionality. PHP fans often say it's a good thing that PHP has MySQL support built right in, but then I point them to the functions
mysql_real_escape_string. What is with that? Was the first function not good enough, that somebody had to write a second one that escapes strings better? And they had to create a second function so they don't break existing code that relies on the behavior of the first?
In Perl, if I was using the DBI module for SQL, and I had a problem with the way that DBI escapes my strings, guess what I could do: I could write my own module that either inherits (and overrides) from DBI, or write a new module from scratch with an interface very similar to DBI, and use it in my code. My code could still be written the exact same way:
my $dbh = Kirsle::DBI->connect("..."); my $sth = $dbh->prepare("INSERT INTO users SET name=? AND password=?"); $sth->execute($username,$password);
Besides the "programming language" itself, just take a look inside
php.ini. What's that, you ask? It's a global PHP configuration file. Yeah, that's right: the behavior of every PHP script on your entire server can be dictated by a single configuration script. Aren't config files supposed to be a part of, oh I don't know, applications? Content management systems? And not as part of a programming language itself?
On one hand this explains why a lot of free web hosts allow you to use PHP but not Perl; PHP can be neutered and have all of its potentially risky functionality taken away by carefully crafting your php.ini whereas Perl, being a REAL programming language, can't be controlled any more easily than a C binary can. But on the other hand, just look inside php.ini -- there's options in there for how PHP can send e-mails, and how it would connect to a database by default. It even breaks down the databases by type - MySQL, PostgreSQL, MSSQL, etc. Shouldn't database details be left up to the actual PHP code? Apparently not.
So there you have it. I'll never use PHP. It's not even a real programming language. Just a toolkit for rapidly getting a website up and running. What's another name for that? Oh, a Content Management System. Doesn't a PHP CMS sound redundant now? ;)
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php is better than perl and it's not me saying, but the community of developers around the world. if you set php.ini profile to "production" mode, all the security weakness that you have mentioned are gone. also php5 is very modular and object oriented. the functions you mentioned back from php4 were weird i admit but that was way back. i mean you could still use some of those as a backwards compatibility with php4 but they're set to dissapear in the next release. given a problem, it is faster as time to write a solution in php rather than perl. a lot of time consuming detalis like variable type casting is left to the php processor to handle. you can talk about sql injuction to php beginners not experienced php programmers. perl is so cryptic and so not elegant when you look at the code. when you have to understand over 50k lines of code it's really easy to do it in php but not in perl. in php you can use modern programming techniques, like classes and stuff. can u do that in perl? and yea you can write php shell scripts too same you can do it with perl.