Technical Insight

Teaching Code in 2014

Guest post by – JD Glaser

“Wounds from a friend can be trusted, but an enemy multiplies kisses” – Proverbs 27:6

This proverb, over 2,000 years old, is directly applicable to all authors of programming material today. By avoiding security coverage, by explicitly teaching insecure examples, authors do the world at large a huge disservice by multiplying both the effect of incorrect knowledge and the development of insecure habits in developers. The teacher is the enemy when their teachings encourage poor practices through example, which ultimately bites the student in the end at no cost to the teacher. In fact, if you are skilled enough to be an effective teacher, the problem is worse than for poor teachers. Good teachers by virtue of their teaching skill greatly multiply the ‘kisses’ of poor example code that eventually becomes ‘acceptable production code’ ad infinitum.

So, to the authors of programming material everywhere, whether you write books or blogs, this article is targeted at you. By choosing to write, you have chosen to teach. Therefore you have a responsibility.

No Excuse for Demonstrating Insecure Code Examples

This is year 2014. There is simply no excuse for not demonstrating and explaining secure code within the examples of your chosen language.

Examples are critical. First, examples teach. Second, examples, one way or the other, find their way into production code. This is a simple fact with huge ramifications. Once a technique is learned, once that initial impact is made upon the mind, that newly learned technique becomes the way it is done. When you teach an insecure example, you perpetuate that poor knowledge in the world and it repeats itself again and again.

Change is difficult for everyone. Pepsi learned this the expensive way. Once people accepted that Coke was It, hundreds of millions of dollars spent on really cool advertising have not been able to change that mindset of that opinion. The mind has only one slot for number one, and Pepsi has remained second ever since. Don’t continue to enforce security in the mind as second.

Security Should Be Ingrained, Not Added

When teaching, even if you are ‘just’ calculating points on a sample graph for those new to chart programming, if any of that data comes from user supplied input via that simple AJAX call to get the user going, your sample code should filter that sample data. When you save it, your sample code should escape it for the chosen database; when you display it to the user, the sample code of your chosen language should escape it for the intended display context. When your sample data needs to be encrypted, your sample code should apply modern cryptography. There are no innocent examples anymore.

Security should be ingrained, not added. Programmers need to be trained to see security measures in line with normal functionality. In this way, they are trained to incorporate security measures initially as code is written, and also to identify when security measures are missing.

When Security Measures are removed for the sake of ‘clarity’ the student is being taught unconsciously that security makes things less clear. The student is also being trained directly by example to add security ‘later’.

Learning Node.js In 2014

Most of the latest Node.js books have some great material, but only one out of several took the time to properly teach, via integrated code examples, how to properly escape Node.js code for use with MySQL. Kudos to Pedro Teixeira, who wrote Professional Node.js from Wrox Press, for teaching proper security measures as an integral part of the lesson to those adapting to Node.js.

Contrast this with Node.js for PHP Developers from O’Reilly Press, where the examples explicitly demonstrate how to insecurely code Node.js with SQL Injection holes. The code in this book actually teaches the next new wave how to code wide open vulnerabilities to servers. Considering the rapid adoption of Node.js for server applications, and the millions who will use it, this is a real problem.

The fact that the retired legacy method of building SQL statements through insecure string concatenation was chosen by the author as the instruction method for this book really demonstrates the power of ingrained learning. Once something is learned, for good or bad, a person keeps repeating what they know for years. Again, change is difficult.

The developers taught by these code examples will build apps that we may all use at some point. The security vulnerabilities they contain will effect everyone. It makes one wonder if you are the author whose book or blog taught the person who coded the latest Home Depot penetration. This will be code that has to be retrofitted later at great time and great expense. It is not a theoretical problem. It does have a large dollar figure attached to its cost.

For some reason, authors of otherwise good material choose to avoid teaching security in an integral way. Either they are not knowledgeable about security, in which it is time to up their game, or have fallen into the ‘clarity omission’ trap. This is a wide spread practice, adopted by almost everyone, of declaring that since this ‘example code’ is not production code, insecure code is excusable, and therefore critical facts are not presented. This is a mistake with far-reaching implications.

I recently watched a popular video on PHP training from an instructor who is in all other respects a good instructor. Apparently, this video has educated at least 15,000 developers so far. In it, the author explicitly states briefly that output escaping should be done. However, in his very next statement, he declares that for the sake of brevity, the technique won’t be demonstrated, and the examples given out as part of the training do not incorporate the technique. The opportunity to ingrain the idea that output escaping is necessary, and that it should be an automated part of a developer’s toolkit, has just been lost on the majority of 15,000 students because the code to which they will later turn for reference is lacking. Most, if not all, will ignore it as a practice until mandated by an external force.

Stop the Madness

In the real world, when security is not incorporated at the beginning, it costs additional time and money to retrofit it later. This cost is never paid until a breach is announced on the front page of a news service and someone is sued for negligence. Teachers have a responsibility to teach this.

Coders code as they are taught. Coders are primarily taught through books and blog articles. Blog articles are especially critical for learning as they are the fastest way to learn the latest language technique. Therefore, bloggers are equally at fault when integrated security is absent from their examples.

The fact is that if you are a writer, you are a trainer. You are in fact training a developer how to do something over and over again. Security should be integral. Security books on their own, as secondary topics, should not be needed. Think about that.

The past decade has been spent railing against insecure programming practices, but the question needs to be asked, who is doing the teaching? And what is being taught?

You, the writer, are at the root of this widespread security problem. Again, this is 2014 and these issues have been in the spotlight for 10+ years. This is not about mistakes, or being a security expert. This is about the complete avoidance of the basics. What habit is a young programmer learning now that will effect the code going into service next year? and the years after?

The Truth Hurts

If you are still inadvertently training coders how to write blatantly insecure code, either through ignorance or omission, you have no business training others, especially if you are successful. If you want to teach, if you make money teaching programming, you need to stop the madness, educate yourself, and reverse the trend.

Write those three extra lines of filtering code and add that extra paragraph explaining the purpose. Teach developers how to see security ingrained in code.

Stop multiplying the sweet kiss of simplicity and avoidance. Stop making yourself the enemy of those who like to keep their credit cards private.

About JD

In his own words JD, “Did a brief stint of 15 years in security. Headed the development of TripWire for Windows and Foundscan. Founded NT OBJECTives, a company to scan web stuff. BlackHat speaker on Windows forensic issues. Built the Windows Forensic Toolkit and FPort, with the Department of Justice has used to help convict child pornographers.”

Tags: web application security, web security