He speaks SO LOUD... lol... I think the entire cafe knows how to hack websites by now...

One of the better 'funny pictures' I have seen, was a numberplate on a pretty fast car, which had an SQL instruction to drop some tables... hello speed cameras ...

Simply: don't ever ever trust user input.

"; DROP ALL DATABASES; dammmit.

This is the St Pancras Renaissance hotel in London - great that they let us film after our original location fell through - shame they wouldn't let me use lights though! >Sean

>"You can read people's passwords..." Well hopefully they're hashed anyway

One finger: "Facebook was originally written in PHP" Second finger: All other things. Nice one.

Tom Scott is awesome! "If you can't explain it to an eight year old, you don't fully understand it yourself!" -Unknown Smart person

"It's a hack on top of a hack.... That's a hack, and we've had to put more on top of that, and more on top of that, and more on top of that." It's a hack stack!

"It works, but it's clunky." - PHP in nutshell.

"Shouldn't work any more but still does." Just ask TalkTalk's IT department...

I am familiar with SQL injections but it doesn't work on any websites that are worth messing with

Oh Tom Scott, you always manage to make us feel just a tad bit more paranoid.

Amazing that he knows I'm a camera, I'm impressed!

Description amended to be less PHP specific - he does explain using PHP though, however little the PHP specific content >Sean

This video is good but makes it sound if a website is poorly coded (so SQL injection is possible) that the database server has no security and is an open platter i.e if a malicious user attempts to run a DELETE, DROP DATABASE command they will be able to do this. If the security on the database side has been granted appropriately the user specified in the connection string of the web application will not be able to execute these commands. All users should only be granted permissions required to do the tasks they are going to use. There is no need for a web application needing to have the DROP ALL DATABASES or similar commands. Not trying to water down the risk just making it clear that the problem lies on the developer (code) and administrator side (permissions).

I literally came to the video to see if he pronounced it as "sequel" or S.Q.L. I got my answer instantly! :D

Good ol' Bobby Tables.

The correct way to think about this: when you are writing code that generates SQL, you need to generate it according to the SQL syntax. When you inject a string into an SQL statement, you need to convert that string into an "SQL string literal". This is done by adding the quotation marks at the beginning and end and escaping any character that has a different meaning in an SQL string literal than in a plain string (backslashes, quotes, etc...). The SQL syntax specification shows you where these string literals are allowed in a statement. If you are putting an integer into your SQL, you need to convert it to an "SQL integer literal", which is usually done just by converting it to a string. (Not an SQL string literal-just a string.)

Oh this should be some nostalgic fun, I remember back in highschool when injecting some code into a text field and... this video is from 2013. This video is from 2013? This video is from 2013! How in holy hell could ANYONE leave such a vulnerable area of security wide open this long?

Love the non ordinary video background. Nicely explained topic. Thank you.

Really enjoy the lighting and setting of this one. Informative person as well. Seeing a large increase in quality on this channel and it's much appreciated.

Tom is so passionate about this stuff. It is truly amazing to watch him explain stuff.

"It really shouldn't work anymore, but still does" is the best description of SQL injection I've ever heard.

Actually I love his passion for the language and the whole subject itself. You can practically see the fire in his eyes. great work helped a bunch

Thanks for these videos... In my experience of web programming as an amateur, Security issues have never been something I have come across all that often. It's good to learn more about them.

Great video. Had a web interview a few weeks ago where I needed to know what an SQL injection is, and while I did try and explain it with my limited knowledge, I learned a lot more about it from watching this video. Thanks for the upload, and I'd also love to see more of Tom.

This guy is one of the best on your channel! Get more videos from him!

Robert'); DROP TABLE Students;--

I love your channel name and the videos are great! It really satisfies my love of technology, but makes me wanna learn more!

funnily enough, I got a SQL course ad for this video.

This guy is the most entertaining and easy to learn from guy on computerphile! More please!

Really liked Tom's way of explaining, I too would like to see more of him!

Just got out of jail because i tried this 5 years ago. THANKS ALOT FOR THE WARNING TOM

I quite like the moody lighting, gives it a nice atmosphere, Tom was a joy to listen to aswell.

Love how this turned into a PHP promotional video with our host feeling the need to justify his usage of PHP! :D

More of this guy. I always wonder if the other people in the restaurant (?) cant help but listen in on the riveting conversation going on.

moar videos with this guy pls, he's amazing; he manage to output such concise information with ease

This is a really tough thing to explain to non-technical people, and this guy did a great job of it.

Extremely well explained. Great job!

Python has taught me really well with strings and escaping. Of course Ive learned more than escaping and learn strings, but I still am thankful for learning it.

Great explanation, more videos with Tom please.

Yay Tom is back! Great video as always!

I'd love to see more about security from Tom, he just does a wonderful job explaining things.

The lighting in this video is really good.

or use an api that discourages raw text queries -- which is good practice both for security as well as for interoperability between different database software.

as hacks go there are worse ones *heavy sigh* - There speaks someone who has had to deal with them! I know that sigh all too well.

Going to show this video to our apprentice. He is going to learn SQL in school soon. Best wishes from germany!

I don't understand who dislikes these videos, no matter what there are people who will dislike every video on youtube

Great video! i really enjoy listening to Tom!

Why does every comment on this video have no reply’s.

thank you so much for uploading this

Great vid !! There is a lot of confusion about prepared statements at the moment. It's more than string building for onwards processing. The SQL statement is parsed and optimised for execution by the RDBMS. The variable is inserted prior to execution by the optimiser. In general, it's a good thing to prepare when you can. Just trust me. Most DBAs will have a large list of their commonly executed statements. It's safer and they gain some element of control over the SQL being executed.

I seriously love this guys enthusiasm

This guy is phenomenal; more of him please!

Yes, another KZread user suggested the same. I checked it out recently and it's really nice. Thanks.

PHP is only fun at the beginning.

Thanks for the video, I have a much much better understanding of how this works now.

Thank you. The analogy in the beginning is genius.

"Prepared statements" - this is also called parameterized queries, right?

"...someone who uses Windows." The expression at 8:31 is priceless! :D

I really like this guy, very enthusiastic, reminds me of my lecturer for databases

Me and my friend always joked about naming a kid "DropTable" in our IS SQL intro course. But I guess now I realized it should be something along the lines of: Frank";Droptable

He clearly said it wasn't just a PHP specific problem. Great video!

Loved the video, great work!

Great info! SQL injection is a classic security flaw

I liked this bloke, he's very passionate about the subject which helps him avoid the boredom that can creep in when listening to a talk on programming. Excellent topic too; I'm neck deep in learning PHP at the moment, so I appreciate the heads up about the security risks.

There's some missing context for this video that would be really interesting. Even though I've used computers for most of my life, I never actually knew what a relational database was or how it works until a few years ago when I asked my instructor about them while taking a class that was only tangentially related to them. I think it's a very interesting topic that more people should know about, because it's pretty much at the conceptual root of everything a modern computer does. Do that video!

reminds me of xkcd 327 where a mom names her child "Robert'); DROP Table Students;"

This video is going to be the response to so many stackoverflow questions.

Love the colorgrading on this one.

Thanks, Sai Vineet, I appreciate the help. :)

These sorts of practices make me cringe inside. I salute you for your continued efforts.

Awesome video! Personally, I think that HTML, Javascript and PHP should be taught in every high school worldwide, if for no other reason than the problem solving skills and understanding of how the internet works gained in the process. No offense to the other client-side and server-side scripting languages.

Gonna change all my code to prepared statements right now. Thank you!

I freaking love Tom Scott, everyone should.

I really like this guy, he speaks with passion and intelligence

I am a professional database expert and I know that the language I am a specialist in, DB2, that 2 two things... 1 - This has been a well known security issue for many years, and any DBM or security expert would be fully aware of these specific issues 2 - Even if for whatever reason someone was able to input commands they shouldn't be allowed to input.. 2A - There are restrictions on who is allowed to perform what operations and on which table(s)(and even which individual records). Even if someone was able to hack the command stream and input malicious commands, any reasonable database will have very easy to implement restrictions that make sure nobody could ever do or view anything they aren't supposed to, and CERTAINLY not do any sort of potentially seriously disruptful actions like deleting data or dropping all databases, lol. Just a very simple restriction on any potentially powerful commands to only the database admins would nullify any of these potential threats. 2B - Even IF something catastrophic was performed like "drop all databases" there are methods of restoring the database to previous states, not just by having BACKUPS saved somewhere, but by diagnostic logs that can be used to roll the environment back in time. I suppose it's possible to imagine a malicous attack that was smart enough and all-inclusive enough to delete all backups and relevant data needed to restore the environment, but just keeping a seperate copy of backups on a completely separate system would alleviate that possibility.

The recent ‘Super Mario World (1990)’ speedrun uses code injection in very fascinating ways that I don't understand. There is even a way to play PONG on the game using in-game sprites and complicated code injection.

I love that he writes things on old continuous-feed paper.

This is one of those videos that have few comments but all from 6 years ago. And no replies, for some reason.

On some websites it's intended for you to not be able to save some images or get a popup or have a chance to be redirected instead, when you click on a link. On some lower end websites you can go around all that by looking at the source code. Often there are links in the code that reveal the url of the images or you can figure out how to change the text of the link address (right click -> copy link address) to open it without extra popups.

thanks tom, awesome explanation

I am really liking this guy. more please!

In php and all other modern programming languages the classes and functions to communicate with database are made so well I don't really have to worry about escaping the value. (pdo for example. no idea why would anyone still use mysql or mysqli even)

This guy is great at teaching.

You're right. For me, using PDO implicitly means "use it properly" i.e alway prepare the statements. Thanks for pointing out.

There's a fix for this. It's called not using PHP

i am a greyhat hacker and always send this video to webmasters of vulnerable websites in the hope that they fix it

I'd like to hear more detail about other methods of injections. I've always been under the impression that properly escaping your inputs was enough to be safe...

so is SQL injection similar to XSS or am i completely wrong here?

bobby drop table students anyone

this technique was used by the characters in jk rowlings "a casual vacancy" to great effect!

Well, adding abstraction on top of another one to cover-up mess, starts to become clumsy. I've switched to C couple years ago, and I never regretted doing it since. With ~1 year of C experience, in couple weeks, I was able to write H T T P server from scratch using sockets and pthreads. In another couple weeks, I had dynamic pages and AJAX going. It looks daunting at first, but unless you try, you'll never know how handcuffed you were with PHP.

How did you isolate his voice from the surrounding noise?

SQL was designed under the name SEQUEL (Structured English QUEry Language), but Sequel just so happened to be a trademarked name of a UK company called Hawker Siddeley Aircraft so it had to be changed. From that, we can assume both ways of saying are correct since Sequel was the name originally intended but "Es-Kyoo-El" is the amended one.

Tom, have you read "PHP: a fractal of bad design" on veekun? I think you may find the article very enlightening.

Does limiting the amount of access that the user has using sql permissions, say, in an oracle DB also solve the issue on its own? Say the user that logs in can only select data from the db, and only from certain tables and you deny them the 'drop', 'delete', 'alter' and other dangerous commands. Would that nullify the threat that injections pose? A hacker trying an injection would get back a 'you don't have permission to perform this operation' message, right? In the real world I'm assuming you use setting permissions in conjunction with the other techniques described in the video to make sure your data is 'safe,' not just relying on permissions alone.

Watching Video: Ok lets not be stupid. After video: LET'S SEND SQL CODES ON EVERY SITE WE KNOW!!!

And “proper handling” means query parameterization (prepared statements) - which was actually described in this video… But you can’t do it with PHP’s mysql_*, hence the “easier in PHP”.