Output is a different matter though but that’s because of rendering content safely down to HTML, JavaScript or JSON (to name a few examples). SQL shouldn’t come into the equation by this point.
SQL injection is really a problem of how you pass parameters to your SQL layer. Parametrized queries are the (easy and widely available) solution. If you are concatenating input to your SQL queries, you're doing it wrong.
It's crazy.
Even if you're using 1990s technology without parameterised queries, it's not like it's impossible to say `insert into users (name, motto) values ('O\'Brien', 'foo\' OR 1=1;')`.
I wish the controls on browsers came with a green V that implements best practices (8+ symbols, no filter) so that people who made websites understand that this is what they should conform to. Not their own misconceptions about password security.
And yes, in 90s php's security sucked, but that was nothing php specific, it was just the sentiment of that time. Everyone did it, in all languages. I remember using tons of $dbh->do() in Perl's DBI back then, intentionally avoiding to prepare statements for a quick and dirty stuff (and most of the scripts back then were quick and dirty stuff). It's in a big part because we were used to building desktop apps and thinking in terms of security that applied for them like being careful about your pointers and input strings lengths and stack overflows and stuff. Web was still pretty new thing.
Ex-shared hosting bod here, who had the joy of managing our PHP environments :(
Sadly in the real world, even after the great big (and pointless) act of deprecating and removing the mysql_* library, naive developers (and experienced ones that should've know better) just moved onto mysqli_* or PDO and still used string concatenation with raw inputs, instead of learning how to parameterise their queries.
Used to drive me flippin' nuts.
True, I stand corrected, I've just checked and Wordpress still does it just like that: https://github.com/WordPress/WordPress/blob/master/wp-includ...
Anyway, there’s a patch release the next day, and somewhere I find the diff. Now I can’t read PHP but I know what string concatenation looks like, especially if someone does a diff on it. I’ll be damned if the diff didn’t fix one SQL string concatenation that was less than five lines from code with the same structure. Scsry.
"I was the first (paid) employee of reddit" https://www.jedberg.net/
I mean...
Also the methods don’t really change across different SQL databases, at least not conceptually. Sure the RDBMS drivers might change but these days that stuff is usually abstracted away into a single framework for SQL. The real significant change would be switching to a NoSQL database but if you’re doing that then it’s not SQL you need to be “sanitising” anyway.
That's a fair criticism. But that is what I've called it for a long time.
> The real significant change would be switching to a NoSQL database but if you’re doing that then it’s not SQL you need to be “sanitising” anyway.
Right, that's why I started off by saying "Sanitize your inputs so that it can be safely stored in your data store", so that it could apply to any data store.
It's just a terminology argument at this point. But my main point was that you need to still think carefully about how you're going to store your data and do it safely, and then also make things safe on the way out, like the article suggests.
I think this is true, but doesn't quite reach the point GP is making: speaking correctly is also important. Calling parameterization input sanitization communicates the wrong message. And abstracting the wrong solution to apply it to a different problem isn't all that helpful. You could just as easily encode or hash input to fit the underlying data format without losing data (except in the case of truncation), but that isn't input sanitization, either.
Input sanitization is strictly checking front-end input against a ruleset and rejecting anything that does not comply. This is fundamentally different than dealing with anything thrown at you and handling it gracefully.
That's validation. Sanitization involves altering the data to make it safe (comes from the word "sanitary").
I think most devs think of sanitization as "make X safe", not "see if X is safe, if not reject" since that is usually called validation.
Using hand sanitizer does not remove your hands if they have harmful bacteria. The hands are still there, just cleaned from (some) of the harmful parts.
Sanitizing your input means changing them permanently. You don't actually want to do that. You want to store exactly what the original value was, but you want to do it safely. When you retrieve it again, it should be the same as it was originally.
If you "sanitize" the input, you won't necessarily have the original value ever again.
(I've seen the line of thought taken one step further: taking the realization that it's impractical to make strings universally safe for any context—even if you HTML entity-encode it twice, what if a recipient decodes it three times?—and concluding that security is hard and we can only approach it asymptotically, so shrugs XSS-like bugs are normal and unavoidable given finite time & budget.)
If the mindset is more like converting units, it becomes clearer. You can't concatenate HTML with a general Unicode string without converting the string to HTML first, any more than you can add inches and centimeters directly. "Cleaning" the centimeters would make no sense.
I think many people would agree that "sanitization" is loosely defined and I think that's exactly what led to the misunderstandings that the OP's article is trying to address.
> that's why I started off by saying "Sanitize your inputs so that it can be safely stored in your data store"
That could be interpreted like "escape quotes at the start of the request if you know that you're using a database where quotes have a special meaning" a la PHP magic quotes, which I'm guessing is not what you meant but it is what the OP is criticizing. The key is that the sanitization (or whatever you want to call it) shouldn't happen until you're ready to insert into the DB, otherwise that data will be coupled with database logic through the whole flow of your app
> And of course use your SQL engine’s parameterized query features so it properly escapes variables when building SQL:
The spread of natural language processing into systems and analysis tools might increase the scope for this sort of thing.
For example what if your NLP is bootstrapped from a shell script and your database content has been stripped of SQL but still contains stuff that might be interpreted as $(sub-shells)? Before long you run into a situation where literally no characters are considered safe (eg even alpha characters in the English alphabet are used as tokens in some programming languages and "what if someone builds a script in one of those languages?").
The only sane way to address the unknown is to treat raw strings as "dirty" and follow best practices when handling them (plus all the usual processes to properly test your code before it's used in production). In which case you're back to no longer needing input sanitisation.
Many data types have some concept of well-formedness, and in those cases, there are pragmatic reasons for only accepting well-formed input that go even beyond the security aspect.
This is why I got confused when you said "but we should acknowledge..." (ie thinking you were raising a point other than what myself and others had already acknowledged).
> Output is a different matter though
"Output" doesn't have to be front end rendered nor even internet facing. It could also be input for another internal process.
If you're saying people should be aware that handling data safely requires more steps than just parametrised SQL then yes I touched on that, as have others, and it's not something anyone is unaware of. Hence why there has been so many high quality posts discussing the different methods of validation, sanitisation and escaping. So it's a rather strange position to assume when you say "we need to acknowledge" given that's what everyone (including me) has been doing. But it never hurts to be categoric about important points like that so your original post is still relevant.
If you're making some other point then I've already had two stabs at deciphering it and failed both times. So it's really not clear what that point is.
However if your intention was just trolling me then fine, I bit and you won.