Tuesday, January 28, 2014

A word about achieving PCI compliance on Smoothwall systems

Many people use security scanning software to audit the network. Either generally as part of day-to-day network operations, or when evaluating some new product.

These tools are fine and serve a useful purpose.  However, as with many tools, they are only as good as the person interpreting the scan results.  Oftentimes we will have customers contact our Managed Services department with an enquiry about the results from such scans.  Occasionally it looks as if the Smoothwall system is rife with issues; the scanning software occasionally highlighting "critical" problems which, on closer inspection, mean very little at all from an real-world threat perspective.

Some examples of the kind of output you might see when scanning:

  • "The web-server presents a self-signed certificate" - This "vulnerability" relates to the fact that the Smoothwall, in a standard shipping configuration, presents its' HTTPS connection with an automatically created self-signed certificate and not one you could purchase from a Certificate Authority. Generally these self-signed certs are adequate for small deployments, and indeed you should consider that the scanner is highlighting a configuration decision made on the part of the administrator, and not showing a real world vulnerability.
  • "TCP Timestamp response" - TCP timestamps are a performance feature for increasing the speed of TCP sessions (RFC1323). Nonetheless, the PCI scan will show a low-level vulnerability because the TCP timestamp can be used to determine the target system's uptime, which is (theoretically) useful to an attacker. In any case this option can be disabled using the Networking > Settings > Advanced page. Note that Smoothwall ships with this option enabled, because in the general case network performance is paramount.
  • "ICMP timestamp response"- Similar to the above. ICMP timestamps, while a feature of a standards-compliant TCP/IP stack, are not very useful to anyone and present a generally useless information leak to a potential attacker. A future update will add the ability to disable these responses through the admin interface all the same. In the mean time, this should not be considered a concern and disabling this feature's biggest benefit will be to succeed in giving you warm fuzzy feelings because your scanner now produces less output.
  • "Apache HTTPD: ETag Inode Information Leakage"- ETags are a mechanism used by browsers to know if URLs have changed on the server, so that the browser can know if it has to re-download the URL. A current Smoothwall will generate these tags, to assist the browser in caching images etc. However, in 2003 a vulnerability report was raised against this behaviour in the Apache webserver which Smoothwall incorporates. This vulnerability relates specifically to the use of ETags in file sharing (NFS) setups, something that Smoothwall has never and will never do. This vulnerability is therefore a prime candidate to be considered a false-positive. But nevertheless, the utility of these ETags is not high, so in a a future update ETags will be disabled just to quieten this report from PCI scanners.
  • "Weak Cryptographic Key" - This is the closest thing to a genuine issue so far listed. Over time, computers become faster. This PCI scanner message is an artefact of this and appears because the previously described self-signed certificate is signed with a 1024 bit key. Only a few years ago this was considered excessively long, but up-to-date PCI scanners now flag this as being not completely adequate. It should be pointed out that breaking a "mere" 1024 bit key still requires many years, even with thousands of computers working at the problem. But still, the NSA is rumoured to be able to crack 1024 bit encryption. And in keeping with PCI recommendations, Smoothwall will switch to using 2048 bit keys in all of it's internally generated certificates and keys.
I hope the reader finds this information useful. As the old saying goes "Security is a process". There are no magic bullets, or black and white answers, but the following is a good start:
  • Keep your systems up to date
  • Expose services only to the people who need, and use them
  • Perform regular audits

Thursday, January 2, 2014

5 New Year's Resolutions to Keep You Safe on the Internet

Happy New Year etc.! OK, now the pleasantries are out out of the way, we can get on with the usual cliche'd list of New Year's Resolutions. You can see I'm going well already with my drive to avoid cynicism in blog posts. These resolutions are aimed more at your personal IT needs than your work life, but you might find a spot of cross applicability in any case.

  1. Housekeeping! - Yes, it is a bit early for a spring clean, but since you've a while to go before you have to break out the washing up gloves and the hoover, you've got time for a bit of a clear-out in online accounts. Each login you have, even if it doesn't protect anything "interesting" or "valuable", is a potential route in for a "cross site privilege escalation" - an attacker could, for example use this to find your postal address or mobile number, which you gave on sign-up, and use these to gain entry to a more "interesting" site, which may have your credit card details. Take a look back at the marketing emails you received in December (they're all at it over the holidays so this is a great time for it) and close down anything you don't use. 

  2. Pesky Passwords - by following the first resolution, you've protected yourself some more against having your password stolen in a site-breach - there's been enough of these in 2013 to sink a battleship. Ideally, you're going to want a different password for each site or service, and there are 2 ways to help reduce your password re-use: First, federate login (eg. through google and facebook), which is very much putting all your eggs in one basket - so you had better watch that basket by following my other resolutions. The second method is to use a password service, such as lastpass. There's no reason not to have a little from column A, and a little from column B, of course. While you're at it, you might check to see if any of the passwords you've been naughtily re-using have been leaked to the world here: https://haveibeenpwned.com/

  3. Backup: Half the Story - and I'm assuming you are halfway there, right? You should back up as much as possible as often as possible. I prefer "everything, all the time" for my files (I personally use backblaze, good value for money!) Other backup services/strategies exist. YMMV. The other side of the backup story is restore. Having your files sent to the great hard disk in the sky is all well and good, but you need to be sure you can get them back. At the very least, pick a few files and try to restore them. You might find a problem you never knew you had!

  4. No Pain, No Gain - 2 Factor Authentication. Yes, I mean you. Pay attention at the back. I know you've been putting this off because you think it will be a pain in the backside. Yes, it will, but once you're used to it, it's minor, and the protection afforded against keyloggers and brute force attacks are not to be understated. This isn't a panacea, but it's one more useful protection against the legion wrongdoers. Many sites & services now support this, a not-particularly-exhaustive list on a post over here.

  5. Finally, One Good Turn... - I'm quite sure you are already 100% on top of all of these suggestions, so I am going to leave you with resolution 5 - go help someone less fortunate (in the Info-security sense) than yourself. Parents, siblings, other-halves, whoever. I know, it's a pain, you're probably the person they'll come to when it all goes pear shaped in any case, and you do enough family tech support as it is, blah blah. Nut up, and go do a good turn. It's the new year, and you'll feel better for it. Not only that, but some of these resolutions will help reduce the calls you get in 2014 from panicking friends and family, and their security is, in many ways, allied to your own. Much like a compromise on a "less important" account that can be priv-esc'd, a security-compromised friend is a threat to your own online safety. On the subject of good turns - if you're after more resolutiony goodness, check out Graham Cluley's list here.
One last thing... thanks for reading the Smoothwall blog in 2013, hope we can keep you interested and entertained in 2014. -Tom