Wednesday, April 22, 2015

A new option to stem the tide of nefarious Twitter images...

Smoothwall's team of intrepid web-wranglers have recently noticed a change in Twitter's behaviour. Where once, it was impossible to differentiate the resources loaded from twimg.com, Twitter now includes some handy sub-domains so we can differentiate the optional user-uploaded images from the CSS , buttons, etc.

This means it's possible to prevent twitter loading user-content images without doing HTTPS inspection - something that's a bit of a broad brush, but given the fairly hefty amount of adult content swilling around Twitter, it's far from being the worst idea!

Smoothwall users: Twitter images are considered "unmoderated image hosting" - if you had previously made some changes to unblock CSS and JS from twimg, you can probably remove those now.

Tuesday, March 31, 2015

Pukka Firewall Lessons from Jamie Oliver

Pukka Firewall Lessons from Jamie Oliver

In our office I’m willing to bet that food is discussed on average three times a day. Monday mornings will be spent waxing lyrical about the culinary masterpiece we’ve managed to prepare over the weekend. Then at around 11 someone will say, “Where are we going for lunch?” Before going home that evening, maybe there’s a question about the latest eatery in town. 

I expect your office chit chat is not too dissimilar to ours, because food and what we do with it has skyrocketed in popularity over the past few years. Cookery programmes like Jamie Oliver's 30 minute meals, the Great British Bake-off and Masterchef have been a big influence. 

Our food obsession, however, might be putting us all at risk, and I don’t just mean from an expanded waistline. Cyber criminals appear to have turned their attention to the food industry, targeting Jamie Oliver’s website with malware. This is the second time that malware has been found on site. News originally broke back in February, and the problem was thought to have been resolved. Then, following a routine site inspection on the 13th of March, webmasters found that the malware had returned or had never actually been completely removed. 

It’s no surprise that cyber criminals have associated themselves with Jamie Oliver, since they’ve been leeching on pop culture and celebrities for years. Back in 2008, typing a star’s name into a search engine and straying away from the official sites was a sure fire way to get malware. Now it seems they’ve cut out the middleman, going straight to the source. This malware was planted directly onto JamieOliver.com.

Apart from bad press, Jamie Oliver has come away unscathed. Nobody has been seriously affected and the situation could have been much worse had the malware got into an organisational network. 

Even with no real damage there’s an important lesson to be learned. Keep your firewall up to date so it can identify nefarious code contained within web pages or applications. If such code tries to execute itself on your machine, a good firewall will identify this as malware.

Wednesday, March 18, 2015

5 Important Lessons from the Judges Who Were Caught Watching Porn


5 Important Lessons from the judges who were caught watching porn

I've never been in court before or stood in a witness box, and I hope I never do. If I am, however, called before a judge, I’d expect him or her to be donning a funny wig and a gown, to be above average intelligence, and to judge my case fairly according to the law of the land. What I would not expect is for that judge to be indulging while in the office, as these District Judges have done. Four of Her Majesty’s finest have been caught watching porn on judicial owned IT equipment. While, the material didn't contain illegal content or child images, it’s easy to see why the case has attracted so much media attention. I mean, it’s the kind of behaviour you would expect from a group of lads on a stag, not from a District Judge! Now the shoe is on the other foot, and questions will be asked about how a porn culture was allowed to develop at the highest levels of justice. Poor web usage controls and lack of communication were more than likely to blame. But speculation aside, the world may have passed the point where opportunity can remain unrestricted to allow things like this to happen. Employees, especially those in high positions, are more vulnerable and need protection. So here are 5 important lessons on web filtering from 4 District Judges: 1. Know Your Organisational Risk – The highest levels of staff pose the highest risk to the organisation. Failures on their part risk the credibility of the whole organisation. 2. Recognise Individual Risk – While not always the case, veteran leadership may be the least computer literate and risk stumbling into ill-advised territory accidentally. 3. Communicate with Staff – Notification of acceptable use policies can go a long way to getting everyone on the same page and help with legal recourse when bad things do happen. 4. Be Proactive – Use a web filter for what’s not acceptable instead of leaving that subject matter open to traffic. If you still want to give your staff some flexibility, try out a limit-to-quota feature. 5. Trust No One (Blindly) – Today’s internet environment makes a blind, trust-based relationship foolish. There is simply too much shady stuff out there and much of it is cleverly disguised. If there is anyone out there who’s reading and thinking, this would never happen in my organisation; my staff would never do that, think again, my friend. Nobody is perfect; the ability to look at inappropriate content knows no bounds, including the heights of hierarchy. We’re all potential infringers, as proved by Judges Timothy Bowles, Warren Grant, Peter Bullock and Andrew Maw.

Thursday, March 5, 2015

Statement: Smoothwall and the "FREAK" Vulnerability

In light of the recent "FREAK" vulnerability, in which web servers and web browsers can be cajoled into using older, more vulnerable ciphers in encrypted communications, we would like to assure customers that the web server configuration on an up-to-date Smoothwall system is not vulnerable to this attack.

Similarly, if you are using "HTTPS Decrypt & Inspect" in Smoothwall, your clients' browsers will afforded some protection from attack, as their traffic will be re-encrypted by the web filter, which does not support downgrading to these "Export Grade" ciphers.

Wednesday, March 4, 2015

Searching Safely When HTTPS is Mandatory

Searching Safely when HTTPS is Mandatory


Nobody wants anyone looking at their search history. I get it. I mean, look at mine  —oh wait, don't—that's quite embarrassing. Those were for a friend, honestly.

Fortunately for us, it's pretty difficult to dig into someone's search history. Google even forces you to log in again before you can view it in its entirety. Most search engines now encrypt our traffic by default, too —some even using HSTS to make sure our browsers always go secure. This is great news for consumers, and means our privacy is protected (with the noticeable exception of the search provider, who knows everything and owns your life, but that's another story).

This all comes a little unstuck though - sometimes we want to be able to see inside searches. In a web filtered environment it is really useful to be able to do this. Not just in schools where it's important to prevent searches for online games during lessons, but also in the corporate world where, at the very least, it would be prudent to cut out searches for pornographic terms. It's not that difficult to come up with a handful of search terms that give potentially embarrassing image results.

So, how can we prevent users running wild with search engines? The first option is to secure all HTTPS traffic with "decrypt and inspect" type technology —your Smoothwall can do this, but you will need to distribute a certificate to all who want to use your network to browse the web. This certificate tells the browser: "trust this organisation to look at my secure traffic and do the right thing". This will get all the bells and whistles we were used to in the halcyon days of HTTP: SafeSearch, thumbnail blocking, and search term filtering and reporting.

Full decryption isn't as easy when the device in question is user-owned. The alternative option here is to force SafeSearch (Google let us do this without decrypting HTTPS) but it does leave you at their mercy in terms of SafeSearch. This will block anything that's considered porn, but will leave a fair chunk of "adult" content and doesn't intend to cover subjects such as gambling —or indeed online games. You won't be able to report on any of this either, of course.

Some people ask "can we redirect to the HTTP site" - this is a "downgrade attack", and exactly what modern browsers will spot, and prevent us from doing. We also get asked "can we resolve DNS differently, and send secure traffic to a server we have the cert for?" - well, yes, you can, but the browser will spot this too. You won't get a certificate for "google.com", and that's where the browser thinks it is going, so that's where it expects the certificate to be for.

In conclusion: ideally, you MITM or you force Google's SafeSearch & block access to other search engines. For more information read our whitepaper: 'The Risks of Secure Google Search'. It examines the problems associated with mandatory Google HTTPS searches, and suggests methods which can be used to remedy these issues.

Tuesday, February 24, 2015

Twitter - Den of Iniquity or Paragon of Virtue... or Someplace in Between?


Twitter - Den of Iniquity or Paragon of Virtue or Someplace in Between


Recently there's been some coverage of Twitter's propensity for porn. Some research has shown that
one in every thousand tweets contains something pornographic. With 8662 tweets purportedly sent every second, that's quite a lot.

Now, this is not something that has escaped our notice here at Smoothwall HQ. We like to help our customers keep the web clean and tidy for their users, and mostly that means free of porn. With Twitter that's particularly difficult. Their filtering isn't easy to enforce and, while we have had some reasonable results with a combination of search term filtering and stripping certain tweets based on content, it's still not optimal. Twitter does not enforce content marking and 140 characters is right on the cusp of being impossible to content filter.

That said - how porn riddled is Twitter? Is there really sex round every corner? Is that little blue bird a pervert? Well, what we've found is: it's all relative.

Twitter is certainly among the more gutter variety of social networks, with Tumblr giving it a decent run for boobs-per-square-inch, but the likes of Facebook are much cleaner — with even images of breastfeeding mothers causing some controversy.

Interestingly, however, our back-of-a-beermat research leads us to believe that about 40 in every 1000 websites is in some way linked to porn — these numbers come from checking a quarter of a million of the most popular sites through Smoothwall's web filter and seeing what gets tagged as porn. Meanwhile, the Huffington Post reports that 30% of all Internet traffic is porn - the biggest number thus far. However, given the tendency of porn toward video, I guess we shouldn't be shocked.

Twitter: hard to filter, relatively porn-rich social network which is only doing its best to mirror the makeup of the Internet at large. As a school network admin, I would have it blocked for sure: Twitter themselves used to suggest a minimum age of 13, though this requirement quietly went away in a recent update to their terms of service.

Friday, January 30, 2015

Plausible Deniability - The Impact of Crypto Law

So, after the recent terror attacks in Paris, the UK suffered from the usual knee-jerk reactions from the technologically-challenged chaps we have governing us. “Let’s ban encryption the Government can’t crack”, they say. Many people mocked this, saying that terrorists were flouting laws anyway, so why would they obey the rules on crypto? How would companies that rely on crypto do business in the UK (that’s everyone, by the way)?


Well, I’m not going to dwell on those points, because I am rather late to the party in writing this piece, and because those points are boring :) In any case, if the Internet went all plaintext on us, web filtering would be a whole lot easier, and Smoothwall’s HTTPS features wouldn’t be quite so popular!


If the real intent of the law is to be able to arrest someone just for having, or sending encrypted data - the equivalent of arresting someone for looking funny (or stepping on the cracks in pavements). What would our miscreants do next?


Well, the idea we need to explore is “plausible deniability”. For example, you are a De Niro-esque mafia enforcer. You need to carry a baseball bat, for the commission of your illicit  work. If you want to be able to fool the local law enforcement, you might also carry a baseball. “i’m going to play baseball, officer” (may not go down well at 3 in the morning when you have a corpse in the back seat of your car, but it’s a start). You conceal your weapon among things that help it look normal. It is possible conceal the cryptography “weapon” so that law enforcement can’t see it’s there so they can’t arrest anyone. Is it possible to say “sorry officer, no AES256 here, just a picture of a kitteh”? If so, you have plausible deniability.

What’s the crypto equivalent? Steganography. The idea of hiding a message inside other data, such that it is very hard to prove a hidden message is there at all. Here’s an example:



This image of a slightly irritated looking cat in a shoebox contains a short message. It will be very hard to find, because the original image is only on my harddisk, so you have nothing to compare to. There are many steganographic methods for hiding the text, and it is extremely short by comparison to the image. If I had encrypted the text… well, you would find it even harder, because you couldn’t even look for words. It is left as an exercise for the reader to tell me in a comment what the message is.