Friday, July 10, 2009

Security and public wireless networks

The other day I wrote of the problem with Social Security Numbers being used as the basis of authentication. I mentioned that the underlying problem was an assumption that security lay somewhere that it didn't.

A recent Fox News article about rogue wireless networks set up by criminals in airports and other public places demonstrates a similar failure to understand where security lies. As pointed out in the article, criminals can easily set up "trojan" networks in places where we would expect a legitimate one to exist.

But from a security point of view, worrying exclusively about these fake networks kind of misses the point. In attempting to make your computer and computer use secure, you should always assume that any network is inherently insecure. It should not matter whether you're connecting via the "official" JFK Airport network or its fake counterpart. The problem isn't that you need to avoid sending confidential details encrypted over the hacker's network, or update your antivirus specifically for connecting to that network. You should always be taking such measures for any network. If you've got your security policy right, then connecting via the hacker's network should be completely safe! You're security should not be relying on a particular network being "safe"; no network carries such a guarantee-- and especially no publicly accessible network (note that even if you had to type in a password to access the airport's network, it's still a public network!).

As well as having a paid-for firewall and antivirus that you keep up to date, you should be taking measures such as always accessing e-mail via an encrypted service, ensuring any financial transactions are made via an encrypted service, heeding warnings from your browser about problems with certifiates, not installing software from untrusted web sites, making sure you e-mail service has built in antivirus, and in any case not opening e-mails from suspicious recipients.

Tuesday, July 7, 2009

Social Security Numbers and "security": a case of misguided assumption

The research on predicting social security numbers published today by Alessandro Acquisti and Ralph Gross from Carnegie Mellon University unfortunately highlights a fairly classic case of something we do all too often: basing security on something that was never secure-- and never really intended to be secure-- in the first place.

Much of the information that we readily pretend is a valid authentication key (such as Mother's Maiden Name, Date of Birth and Post Code-- and indeed Social Security Number) has really always been publicly available information. The parameter that has changed is how financially viable it is for a criminal to access the public records necessary to deduce this "secret" information. The SSN allocation scheme is perfectly well documented, public information, and the scheme clearly has no element of security built into it whatsoever. The historical origins of the scheme are also documented: the scheme has no security now, never did and was never intended to.

So what do we need to do about this? We need to understand where security actually lies, and not pretend that it exists in places where it doesn't. In most cases, the "security" does not currently lie in whether somebody can guess your PIN number, forge your signature, find out your mother's maiden name or guess the last couple of digits of your SSN. Our measures for preventing discovery of these largely unsecret "secrets" are predictably diabolical, and they are thus extremely weak forms of authentication. A transaction that is "authenticated" by an SSN or signature is essentially unauthenticated and the security of that transaction relies on it being quickly reversed in the event of fraud. So long as users, banks and lawmakers all understand this, the situation isn't so dire. The big danger comes when we pretend that there is security and authentication where there really isn't.

Friday, July 3, 2009

Java, XML and XPath

The Javamex site now includes a basic introduction to using XML and XPath in Java. Java provides various means to read XML, but XPath is generally the most practical for moderately-sized XML documents. XPath effectively allows you to treat a document as a file system and refer to elements by their "path" within the document.