On the utility of technical security

It is often said that the system is only as strong as the weakest link. When you have good security and strong passwords, the weakest link will be the human. As has always been. Think of how the system can be recovered from a breach when the problem is not technical but human.

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Common passwords blacklist

Any system that implements password authentication must check whether the passwords are not too common. Every system faces the brute-force attacks that try one or another list of most common password (and usually succeed, by the way). The system must have a capability to slow down an attacker by any means available: slowing down system response every time an unsuccessful authentication is detected, blocking an account for a short time after a number of unsuccessful authentication attempts or throwing up captchas.

Your password is not long enoughHowever, even the most sophisticated system fails if the user’s password is the most common word: “password”. The attacker simply succeeds then at once because that is likely to be the first word tried. So we need a system for blacklisting passwords that are thought of as most likely to be tried in a dictionary brute-force attack. This may be annoying for users of the system who may prefer to use a simple word as a password but this is the reality – any simple word used as a password is likely to be a security hole and must be banned.

While implementing the user login plugin for CakePHP I came across this simple question. Where do we get the password lists to check the newly entered passwords against? And here is a resource I can recommend: 62K Common Passwords by InfoSec Daily. Depending on your system’s speed you could use a smaller file of 6 MB, a 1.5 GB file that should take care of most common passwords or fuse the files into your own list.

Quantitative analysis of faults shows that…

Not to worry, we are not going to get overly scientific here. I happened across this extremely interesting paper called “Quantitative analysis of faults and failures in a complex software system” published by Norman Fenton and Niclas Ohlsson in ye god old year 2000. The paper is very much worth a read, so if you have the patience I recommend you read it and make your own conclusions. For the impatient I present my own conclusions that I draw from reading the paper.

The gentlemen have done a pretty interesting piece of research that coincides well with my own observations of software development in various companies and countries. They worked with a large software base of a large company to investigate a couple of pretty simple theorems that most people take for granted. The research is about general software faults but the security faults are also software faults so this is all relevant anyway.

First, their object of investigation concerned the relationship between the number of faults in the modules of the software system and the size of the modules. It turns out that the software faults are concentrated in a few modules and not scattered uniformly throughout the system as one may have expected. That coincides very well with the idea that the developers are of different quality and experience and the modules written by different people will feature different levels of code quality.

Then, the finding that confirms my experience but contradicts what I hear quite often from managers and coders alike at all levels: the complexity of the code does not have any relation to the number of faults in that module. The more complex (and larger) code does not automatically beget more faults. It is again down to the people who wrote the code whether the code is going to be higher or lower in quality.

And then we come to a very interesting investigation. Apparently, there is strong evidence that (a) software written in similar environments will have similar quality and (b) the software quality does not improve with the time. You see, the developers do not become better at it. If they sucked at the beginning, they still suck ten years later. If they were brilliant to start with, you will get great code from day one. I am exaggerating but basically that is how it works. Great stuff, right?

So, the summary of the story is that if you want to have good code – get good developers. There is simply no other way. Good developers will handle high complexity and keep the good work, bad (and cheap) developers will not and will not learn. And no amount of tools will rectify that. End of the story.

Supply chain: Huawei and ZTE

United States House of Representatives Seal

US House of Representatives published an interesting report about their concerns with Huawei and ZTE, large Chinese telecom equipment providers. The report states openly that there are concerns that the equipment, parts and software may be manipulated by the Chinese government agencies, or on their behalf, in order to conduct military, state and business intelligence. The investigation that the report is the outcome of did not dispel those concerns but made them more founded, if anything. We have to keep in mind that this is a highly political issue, of course. But even then, citing such concerns underlines what we talked about for several years now: the supply chain is a really important part of your product’s security and blindly outsourcing things anywhere is a security risk.

Welcome to “Holy Hash!”

This is a lighter software security blog. I start it now mainly because of two reasons.

First, something has to be done. The recent break-ins at the likes of LinkedIn and Yahoo show that even at the large companies people do not understand the basics of security. By looking at what is proposed and advised under the guise of security to people starting out to write their own web applications I understand that those are not far behind. Should their applications become famous, they will be broken as easily. There needs to be a place to discuss even the most basic things, so people do not keep making the same mistakes over and over again… like if it’s bloody Groundhog Day.

Second, why do we have to talk about software security always with a grave face? Yes, it is a serious subject but that does not warrant the long faces. Lighten up, people! Relax, let the Force flow. Have a break and make a joke. Security can be an entertaining subject. Let’s not make it appear harder than it is.

So here we are, something has to be done and it better be done with a smile. Or a grin… a smirk, a beam, a crack. Not with a frown. I will write my thoughts on software security, you are welcome to comment, make fun of, ask questions and generally have a good time.

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