Thursday, August 22, 2013

Getting Application Security Vulnerabilities Fixed

It’s a lot harder to fix application security vulnerabilities than it should be.

In their May 2013 security report, WhiteHat Security published some discouraging findings about how many application security vulnerabilities found in testing get fixed, and how long it takes to fix them. They found that only 61% of serious security vulnerabilities get fixed, and that on average, it takes 193 days to get them fixed.

Why some vulnerabilities get fixed, or don’t get fixed

Convincing management and the customers paying for software development work – and the developers that need to do the work – that security vulnerabilities really need to be fixed is one part of the problem. Proving that this can be done in a cost effective and safe way is another.

For most organizations, compliance – not operational risk, not customer requirements or other commercial considerations, and not concern for quality – determines whether security vulnerabilities get fixed. WhiteHat customers reported that the #1 reason that a vulnerability gets fixed is because it is required by compliance. And the #1 reason that people don’t fix a vulnerability is because it isn't required by compliance.

One of the other factors that influences how many security vulnerabilities get fixed and how fast they can be fixed is where the system is in its life. It’s a lot easier and much less expensive to fix security vulnerabilities found early in a project, before you’ve written a lot of code that needs to be reviewed, fixed and tested again; when the situation and the system are both plastic enough that you can make course corrections without a lot of time or cost.

Obviously it’s a much different story for legacy systems on life support, where nobody really understands the code or is confident that they can change it safely, and nobody is sure how long the system is going to be around (although these systems almost always hang on longer than anyone expects).

Everything in between is where decisions are difficult to make: the system is already in use and has been for a while, and the team maintaining and supporting it has a full book of committed work to deal with. It can be hard to make fixing security vulnerabilities a priority when things seem to be running fine, and everyone is busy trying to keep it this way, unless maybe compliance is standing over you holding a big enough hammer that you have to do something to show that you are taking them seriously.

What’s it going to cost?

If you can make the case that there are serious security problems that that need to be taken care of, where do you start? A security review could uncover hundreds or even thousands of vulnerabilities – the first time that you do a security scan or pen test of a big system can be overwhelming. How much work is it going to take to “make the system secure”, what is it going to cost?

Denim Group has done some interesting research on understanding how much work is involved in fixing security vulnerabilities.

Like any other bugs in code, some vulnerabilities are easier to find and fix than others. A XSS vulnerability can take anywhere between 10 minutes (stored XSS) to about an hour and a half (stored and reflected) to fix – and most web apps have at least one, often hundreds of these problems. Fixing a SQL Injection problem also takes an hour and a half on average. A missing authorization check? Only 7 minutes. And like any other bugs in code, the coding work is only a small part of the time taken to get the fix done (on average, 30% of the total time). Testing takes around half of the time, and the rest is in getting things setup for making the change, getting the new code built and deployed, and overhead.

Unlike a functional bug, the customer won’t see any immediate advantage in fixing a vulnerability – the code works fine right now as far as they can see. So it’s important that you can fix vulnerabilities without spending too much time or money doing it, and that you can do it without breaking whatever is already working.

This is why Nick Galbreath stresses the value of a Continuous Deployment capability as a pre-requisite to a successful software security program, leveraging Continuous Integration and Continuous Delivery tools and practices so that when developers check in code changes the system is automatically built, tested and it can be automatically deployed if all of the tests pass. It’s not about pushing every code change out immediately – it’s about having a proven pipeline in place for rolling changes out to production quickly and with minimal risk, knowing that you can make fixes and get them out cheaply and with confidence, and that you are able to respond to an emergency if you have to. This will pay dividends outside of security work, reducing the cost and risk of making any software change.

Getting security bugs fixed

Denim Group explains that remediating software security vulnerabilities has to be managed like any other software development project, and they provide some guidelines on how to do it in a waterfally kind of way, with upfront stakeholder engagement and planning: an approach that can work fine for many organizations, especially larger ones.

A more iterative, Agile approach could start with a short, time-boxed spike. Take a couple of smart developers and give them a couple of weeks to review the list of vulnerabilities (if possible with whoever found them), understand which ones are serious and filter out false positives, and pick some vulnerabilities to fix (a few each of different kinds). They should choose which vulnerabilities to work on by trading off what is easy to understand and fix, against the risk of not fixing them. Tools like the OWASP Top 10 or SANS/CWE Top 25 can help with understanding the issues and making these decisions.

SQL Injections would make a good first choice: a serious vulnerability that is easy to exploit and that can have serious consequences, but also easy for a developer to understand and fix. Or a missed authorization check: another potentially serious bug that should be easy to understand, trivial to fix and test. A problem like a mistake in secure password storage might be technically harder to solve, but still easy to isolate and test. Adding server-side validation (instead of validation only at the client) is another easy and good place to start.

It is important that the developers take the time to understand what they are doing and how to do it right: that they understand the vulnerability, why it is a problem, how to fix it correctly, and how to test it (test it to make sure that they actually closed the security hole, and regression test it to make sure that they didn't break anything else by accident). The important thing here isn't to make a few fixes – it’s to learn what’s involved in correctly solving these problems, and know that you can build and deploy the fixed code properly.

Then run another spike. Pick a few other bugs, maybe some that are harder to understand and fix, and some that are easy to fix but less serious (like missing error handling or information leaks), and run through the same steps again.

With a small investment of time like this, you should get an understanding of what work needs to be done, how to do it, what it’s going to cost, and you should also have the confidence that you can do it safely. You should have good enough information to estimate the amount of work that it will take to fix the remaining problems; and a good enough understanding of risk and cost trade-offs that need to be made, what problems need to be fixed – and can be fixed – sooner or later.

Now you can add the remaining bugs that you plan to fix to your backlog. You might decide to fix as many of them as you can all at once in a hardening sprint, or prioritize and fix them with the other work in your backlog.

You can’t fix, or effectively plan to fix, security vulnerabilities until you understand them. Once you understand the problems (what the bugs are, what needs to be fixed and why), and how much it is going to cost to fix them, and once you have the confidence that you can fix them properly, you can treat security vulnerabilities like other bugs – decide what needs to be fixed and when by trading off cost and risk with the other work that you have to get done. Remediation work becomes just another software development problem to be managed, something that developers and managers already know how to do.

Wednesday, August 14, 2013

Looking for Answers at Agile 2013

I went to Agile 2013 last week in Nashville to look for answers on how Agile development ideas and practices could help more with high integrity, high assurance development; scale to handle large projects and programs; and improve the working environment for mature, high performance teams.

The Sessions

There was a lot going on, with over 200 sessions, informal workshops, lightning talks, Open Jams and other presentations.

A bunch of talks and workshops on soft people skills: team building, leadership issues, managing conflict, coaching, brainstorming games, personal assessments and personal development. Several sessions on scaling issues and approaches for managing large projects and programs, UX design, design modeling, how to get testing done in Agile teams, product requirements definition and backlog management, and a handful on code quality (technical debt and refactoring and coding challenges), one on Kanban and one on application security.

There was also a full track on devops: most of this was introductory stuff on improving packaging and build and implementing continuous delivery, and basics on getting developers and ops working together and why. Devops is a natural next step for many organizations looking to be more agile – what’s the point of being faster and more responsive in product design and development, if you crash into a brick wall at operations? But devops has to move out of the friendly homogeneous chef/puppet/noSQL Webops niche and shed the hype about how deploying 10 or 100 times per day is the way to be cool, in order to be relevant to the rest of the world. If not, “devops” is going to end up meaning buying some expensive configuration management and deployment tools from IBM or HP, which won’t make the world a better place and will be a disappointment to everyone except the vendors.


Many of the sessions early in the week were introductory level overviews and experience reports. A couple of points of interest included an intelligent and entertaining session on managing requirements and backlogs by Jeff Patton and some real-life experience reports on getting quality and testing under control in large Agile shops.

Most of the highlights for me came on Thursday, when I attended some especially good workshops on dealing with organizational and political issues in program management (how to build broad-based trust across the organization, identifying and dealing with hidden dependencies); getting the team together to craft Abuser Stories, looking at features from an attacker’s perspective to help build application security into Agile development; and a technical session on practical refactoring.

There continues to be a lot of confusion about what refactoring is and what it isn't, as demonstrated by two very different sessions at the conference on refactoring and code quality. The first described well-intentioned but misguided efforts by the Egyptian government to encourage large-scale “refactoring” of legacy code at some Egyptian technology companies, all but one of which failed – the one project succeeded because they severely limited the amount of code cleanup work to a small percentage of time and restricted developers to making only simple refactoring changes to start, until the developers and managers understood what they were doing.

This isn't refactoring: using refactoring techniques and tools is not refactoring. The real advance in refactoring isn't in cataloguing obvious techniques for cleaning up code. It is in defining a disciplined, iterative approach for cleaning up the structure of code immediately before and after a developer makes changes, as an integral part of development and maintenance. Restructuring is supposed to be part of development, not something that needs to be or should be done in a project on its own.

"You should not need a budget to refactor. You should refactor every chance you get."

Llewellyn Falco and Woody Zuill showed how this can be done properly, in a ballsy, well run session where they did live refactoring of code, removing clutter, complexity and cleverness, and then eliminating duplication, all in small steps that took a few minutes at most so that the code could be left at any point in better shape than when they started. They showed what techniques and tools could be used safely, how simple refactoring could be done on code that you don’t understand well (or at all) in order to make it more understandable, and what the payback was for making different kinds of changes.

Themes and Memes

There were a few ideas that came up frequently in the sessions and talking to people at the conference.

Product Ownership is a serious problem, especially in big companies. The simplified Product Owner (“the one throat to choke”) approach doesn't work, even if it is still the official dogma for Scrum. Most Product Owners don’t understand what they are supposed to do, or have the time to do it even if they do know what to do. And of course the single Product Owner idea doesn't scale either – most larger organizations are trying hybrid approaches with product managers, business analysts and other experts filling in at different levels.

Like any good conference, you get as much or more out the other people that you meet there, as you do out of the speakers and vendors.

Many of the people I talked to were working at big (sometimes really big) companies, trying to introduce Agile into big (often really big) projects and programs, and trying to make or remake their careers in an Agile world. What became clear is that Agile doesn't solve all of the problems that come up in large organizations. There are no good answers for executive demands for predictability (because software development is only a part of what needs to be delivered and coordinated in most organizations), or how to communicate and collaborate in massive programs with hundreds or thousands of people that run for years across departments and countries, or how to deal with power politics and organizational inertia, or how to satisfy governance and compliance requirements.

Some people are trying to adapt and integrate Agile practices using SAFe or Disciplined Agile Delivery, but most are putting together something on their own, with Scrum at the team level and PMO practices at higher levels. A lot of organizations are still trying it out before rolling it out, but there are few success stories so far.

Most people seem to accept that spending some time upfront to get the team together and understand what they really need to build is a necessity – you can’t just start off incrementally and iteratively building something. But most people wish it wasn't called “Sprint 0”, because it's not a sprint, it's a separate but important upfront step focused on discovery and simplifying things as much as possible from the beginning.

Getting the requirements right was another important focus area for everyone. The Lean concept of shaving requirements down to come up with a Minimum Viable Product is recognized as the only way to assure success, especially for people running big projects and programs – if you can’t give the business or customer everything that they want, make sure you at least give them the minimum that they need.

Most speakers (but not all) agreed that requirements should be defined in whatever format that makes sense, whatever is needed to get the point across: big stories or small stories, sketches or pictures, detailed specs if you have them, tests if you can get them defined upfront. Jeff Patton emphasized that the simplified story template

as a [type of user] I want [to do something] so that [reason]
is useful as a starting point, a learning tool, but it isn't necessary or even practical to try to fit every requirement into a standardized format.

There was also a strong emphasis on the need for coaching and training (maybe because so many of the speakers were coaches or trainers?), that you shouldn't (or at least don’t have to) try to do all of this without help.

Exhibitors and other things seen and heard

The exhibition floor was surprisingly small. Training firms and firms offering coaching, Agile project management / ALM tools which all looked pretty much the same to me, and a couple of automated testing tools suppliers desperate to convince you that what they are selling is so much better than those tools like QTP that you wasted so much time and money on in the past.

How you can tell IBM doesn't really "get" Agile or Lean:

URL for Scrum.Org:
URL for IBM’s Agile/Lean practice:…

One Kanban training and certification vendor insisted that “Kanban is not an Agile practice” (although they were at an Agile conference). Another vendor cleared this up by explaining that there were “10 reasons that Kanban is like bacon”.

Other things seen.

There was a cool lighting talk by a scary dude wearing Google Glass on D-Wave’s quantum computer. It had nothing to do with Agile development but it was indeed cool.

Some speakers were riding on their reputation, and put little or no effort into their presentations: any session that had a guru sitting on a red couch on the stage was pretty much a waste of time. I don’t care if somebody worked on a project with Kent Beck 13 years ago, or if they were invited to Snowbird in 2001 but couldn't make it, or they showed up at that meeting long enough to agree on the manifesto before hitting the slopes. What matters is whether what they know and what they have to say today is relevant, do they understand and can they help solve the problems that people are facing now.

Other things heard:
“TDD is like teenage sex: everybody is talking about it, but not that many people are doing it.”
“Don’t estimate or worry about story points. Just make all your stories the same size and count them.”
Umm…How do you get them all the same size without estimating them???
“Team building by itself is useless. You have to follow it up and get people working together on something important for a team to form.”
“If you look at any product that you love using, I can guarantee that the reason that you love it is not because it was shipped on time.”

Keep Looking

I didn't get all of the answers that I was looking for, and I don’t think that anyone I met at the conference did either. But it was a good opportunity to understand the challenges that everyone is facing, and it was good to see so many smart and serious people working hard on solving them. It gives you hope that things are going to get better.

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