The issue is trusting input you're receiving from users or the wild world out there. User data always needs to be sanitized in some way shape or form. Assume very little on the web.

Think of every language as a strictly typed, pure functional programming language, where I/O is the big bad world out there and evil and blocking and complicated. Likewise, on the web you should treat any inputs as being evil... (ok, so the comparison is far from perfect, but the idea holds true)

I think you've conflated "not trusting" user data with sanitizing it. To use an analogy from SQL, using prepared statements/parameterized queries doesn't sanitize user data, but it also doesn't trust it (as it doesn't treat data as code). More generally, blacklist sanitizing is a losing game from the outset, whitelist sanitizing is hard, your best bet is to not treat data as code to begin with.

"Always validate your inputs" is unfortunately one of the least useful bits of security advice given to developers; it is only epsilon away from "never make mistakes".

I agree with you, but also pointing out a strength of a language that supports phantom types helps this issue quite a bit. You can design your DB API to not allow unquoted queries.

Rails does the same thing and it's insanely useful, you just need to know what you're doing and ensuring you're protecting against this.

Which means a) You're going to forget it at least once. b) For every developer mindful of this, there will be hundreds not knowing about it.

If you ever put "you just need" into a sentence about security you've already lost.

> a) You're going to forget it at least once.

Which is why you should never process raw input in multiple places in your app. One method I've used for over a decade of webdev in any language: there's only one place to get the input from, and that place requires you specify what input is allowed.

Any security practice that addresses an insecure default state by starting with "you should never..." is doomed.

The default Rails way of using Activerecord will automatically sainitize inputs for you. Not turning it into an associative array doesn't add anything to security.

User input need to be sanitized always. Rails make it easy and is the default way.

There's nothing stopping you from passing unsanitized params to the database. I.e. where("name LIKE '%#{params[:name]}%'") instead of where("name like ?", "%#{params[:name]}%"). While the 2nd option is definitely the recommended way to do it, there's nothing stopping you from doing it the wrong way, and I bet many do.

The thing is, it's easier to do it the right way. It requires a special, deliberate effort to do it wrong. That seems like a reasonable implementation of a "magic" feature. PHP, as usual, gets it exactly backwards. It's easier to do it wrong, and requires a special, deliberate effort to do it the secure way.

Yeah maybe. Depends on the person I think. I actually find it easier to assemble a SQL string myself. If you're new to rails / AR and you're not familiar with SQL then you'll look up and figure out how to assemble the SQL via the ORM methods. If you're new to rails but an old hand at SQL, just building the string is super easy and takes you 2 seconds without looking up any documentation. Of course assembling the string AND sanitizing it requires a heck of a lot more effort.

Regardless, it's not a knock on rails. Just saying it's not necessarily a magic bullet to secure apps (and I don't believe rails nor PHP needs to be).

All true. I was thinking of the submitted link still. Manually sanitizing instead of having something doing that for you is a bad idea because you will forget.

The "hundreds not knowing about it" was was sparked me to submit this to HN. This is important stuff and probably should not be relegated to a php.net footnote.

Edit: It's not actually a footnote -- it's actually just the only item on the lonesome "Security" page.

To be fair, it's the Mongo Security page, not the general security page, which can be found here: http://www.php.net/manual/en/security.php

The web is full of these kinds of issues -- you need to escape, filter, etc, etc, every piece of user data. You either do it yourself or use some kind of abstraction layer (template engine, ORM, etc) to do it for you.

Put differently: "we're all doomed". Squares with our professional experience.

It is a tradeoff between ease of use and security. These sorts of features require the developer to check every single query string consumer or you end up with gaping security holes. That will result in security exploits in any moderately large codebase with multiple developers, it's just a matter of time. I would much prefer to sanitize everything always and force the app developer to spend the 1 line of code to parse into an array when they want that feature.

Tornado always uses lists, even when there's a single parameter. I.e. `?spam=ham&spam=ham&eggs=eggs` results in `{"spam": ["ham", "ham"], "eggs": ["eggs"]}`.

While this may be not as easy to use as simple strings, it is consistent.

Somehow I managed to use PHP for 8 years and never notice this... Time to double check all my input sanitizing code, I guess.

8 years and you didn't know this? I assume it's the part where it turns [] passed vars into arrays. Even still, this is only a problem is you are blindly passing around user input without any verification. The same thing is just as easily accomplished in numerous other languages.

Honestly, I'm trying to figure out how someone could sanitize their input and still be affected by this.

> Honestly, I'm trying to figure out how someone could sanitize their input and still be affected by this.

I don't think you could, unless you tried to write your own sanitizing functions from scratch and somehow screwed it up. In PHP, htmlspecialchars(), mysql_real_escape_string() and addslashes() all do fine sanitizing array input -- either throwing an exception or returning the string "Array".

Hmm. I think these functions escape output, not sanitize input.