02 July 2010

DNS

Posts relating to the category tag "DNS" are listed below.

02 July 2010

Web Site Security Basics for SMEs

Sometimes when I'm out socially and people ask what I do, the conversation progresses to concerns about their own web site. They may have a hobby site, run a micro-business or be a manager or director of a small and medium-sized enterprise (SME)—there's all sorts of great entrepreneurial activity going on.

It is very common for SMEs not to have much time or budget for information security, and the available information can be poor or inappropriate (ISSA-UK, under the guidance of their Director of Research David Lacey, is trying to improve this). But what can SMEs do about their web presence—and it is very unusual not to have a web site, whatever the size of business.

Photograph of a waste skip at the side of St John Street in Clerkenwell, London, UK, with the company's website address written boldly across it

Last week I was asked "Is using <company> okay for taking online payments?" and then "what else should I be doing?". Remember we are discussing protection of the SME's own web site, not protecting its employees from using other sites. If I had no information about the business or any existing web security issues, this is what I recommend checking and doing before anything else:

  • Obtain regular backup copies of all data that changes (e.g. databases, logs, uploaded files) and store these securely somewhere other than the host servers. This may typically be daily, but the frequency should be selected based on how often data changes and how much data the SME might be prepared to lose in the event of total server failure.
    • check backup data can read and restored periodically
    • don't forget to securely delete data from old backups when they are no longer required
  • Use a network firewall in front of the web site to limit public (unauthenticated user) access to those ports necessary to access the web site. If other services are required remotely, use the firewall to limit from where (e.g. IP addresses) these can be used.
    • keep a record of the firewall configuration up-to-date
    • limit who can make changes to the firewall
  • Ensure the host servers are fully patched (e.g. operating system, services, applications and supporting code), check all providers for software updates regularly and allow time for installing these.
    • remove or disable all unnecessary services and other software
    • delete old, unused and backup files from the host servers
  • Identify all accounts (log in credentials) that provide server access (not just normal web page access), such as used for transferring files, accessing administrative interfaces (e.g. CMS admin, database and server management/configuration control panels) and using remote desktop. Change the passwords. Keep a record of who has access and remove accounts that are no longer required and enable logging for all access using these accounts.
    • restrict what each account can do as much as possible
    • add restrictions to the use of these accounts (e.g. limit access by IP address, require written approval for use, keep account disabled by default)
  • Check that every agreement with third parties that are required to operate the web site are in the organisation's own name. These may include the registration of domain names, SSL certificates, hosting contracts, monitoring services, data feeds, affiliate marketing agreements and service providers such as for address look-up, credit checks and making online payments.
    • ensure the third parties have the organisation's official contact details, and not those of an employee or of the site's developers
    • make note of any renewal dates
  • Obtain a copy of everything required for the web site including scripts, static files, configuration settings, source code, account details and encryption keys. Keep this updated with changes as they are made.
    • verify who legally owns the source code, designs, database, photographs, etc.
    • check what other licences affect the web site (e.g. use of open source and proprietary software libraries, database use limitations).

Do what you can, when you can. Once those are done, then:

  • Verify the web site and all its components (e.g. web widgets and other third party code/content) does not include common web application vulnerabilities that can be exploited by attackers (e.g. SQL injection, cross-site scripting).
  • Check what obligations the organisation is under to protect business and other people's data such as the Data Protection Act, guidance from regulators, trade organisation rules, agreements with customers and other contracts (e.g. PCI DSS via the acquiring bank).
    • impose security standards and obligations on suppliers and partner organisations
    • keep an eye open for changes to business processes that affect data
  • Document (even just some short notes) the steps to rebuild the web site somewhere else, and to transfer all the data and business processes to the new site.
    • include configuration details and information about third-party services required
    • think about what else will need to be done if the web site is unavailable (does it matter, if so what exactly is important?)
  • Provide information to the web site's users how to help protect themselves and their data.
    • point them to relevant help such as from GetSafeOnline, CardWatch and Think U Know
    • provide easy methods for them to contact the organisation if they think there is a security or privacy problem
  • Monitor web site usage behaviour (e.g. click-through rate, session duration, shopping cart abandonment rate, conversion rate), performance (e.g. uptime, response times) and reputation (e.g. malware, phishing, suspicious applications, malicious links) to gather trend data and identify unusual activity.
    • web server logs are a start, but customised logging is better
    • use reputable online tools (some of which are free) to help.

That's just the basics. So, what would be next for an SME? If the web site is a significant sales/engagement channel, the organisation has multiple web sites, is in a more regulated sector or one that is targetted particularly by criminals (e.g. gaming, betting and financial), takes payments or does other electronic commerce, allows users to add their own content or processes data for someone else, the above is just the start. Those SMEs probably need to be more proactive.

This helps to protect the SME's business information, but also helps to protect the web site users and their information. After all, the users are existing and potential customers, clients and citizens.

Oh, the best response I had to someone when I was explaining my work: "You're an anti-hacker than?". Well, I suppose so, but it's not quite how I'd describe it.

Any comments or suggestions?

Posted on: 02 July 2010 at 08:18 hrs

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08 December 2009

Your UK Web Site Can Be Shut Down

The use of particular top-level country domain names (e.g. .co.uk or .com) does add an element of trust to a visitor's impression of the site. On Thursday, the Metropolitan Police's Central e-Crime Unit (PCeU) closed 1,219 web sites selling fake designer goods.

Photograph of a painted wooden shop shutter with the word 'CLOSED' painted on itWhilst I'm not suggesting that any readers of this blog were operating these sites, it is worth bearing in mind the sanctions that can be applied by the government for illegal trading. In this case, Nominet who maintain the register for .uk domains, were asked to take down the domain names to protect consumers and companies selling legitimate goods.

If the fake sites had not been on .co.uk domain, they may have been less able to con consumers into parting with their money and not receiving anything or buying counterfeit products, and the PCeU would have had a harder time taking action. Providing sufficient evidence has been gained, it appears these measures were appropriate in the circumstances.

Posted on: 08 December 2009 at 11:31 hrs

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16 October 2009

Warning: Punctuation Marks Can Damage Your Web Site

It seems a missing full stop brought down every web site hosted on a domain ending with .se (the top-level domain for Sweden) on Monday evening.

Partial picture of Table 4/T.50, the basic 7-bit code table, from the ITU-T Recommendation T.50

The .SE registry had apparently performed an incorrect software update but actually a script (program written by a human) had failed to add a terminating full stop (.) to the DNS records in the .se zone. Tested? I guess not.

It reminded me of Google's mishap in May when it flagged every site as potentially harmful by simply adding an extra forward slash (/) character to a file.

And, simple punctuation mistakes can invalidate the HTML of your web page, or stop your application's scripts from running. In July Microsoft created a security flaw in Windows by the addition of an extra ampersand (&) character.

Tim Berners-Lee is still wishing he hadn't put two forward slashes in every URL.

The mighty power of a punctuation mark.

Posted on: 16 October 2009 at 15:24 hrs

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29 September 2009

IP Address Restrictions and Exceptions

It's common for access to some web sites to be restricted to users from particular Internet Protocol (IP) addresses. This is usually in addition to some other identification and authentication method. But other IP addresses are often added to this "allow list" and these should not necessarily be trusted in the same way.

Photograph of a sign with an exclamation mark on a yellow triangle that reads 'Caution - Traffic management Trial - DO NOT MOVE' on a construction site boundary's wire barrier

In a typical scenario, a web site hosted on the internet that is used to administer another web application might be restricted to the company's own IP addresses. Then the developers say they need to check something on the live site, or another server needs to index the content, or someone wants to work from home for a while, or the site needs to be demonstrated at a client's location. All these additional IP addresses are added to the "allow list". These restrictions may be being applied at a network firewall, traffic management system, at the web server, in the application itself, in intrusion detection systems or in log analytical software, or in many of these. These are difficult to manage and in time there will be many IP addresses that no-one knows why they are allowed unless they are carefully documented, and subject to a fixed time limit when they are confirmed again by an appropriate person or removed. These extra addresses are quite often hard for someone else to guess.

However, there is another area where IP addresses are added to "allow lists", and this is for remote monitoring and testing services. These might be checking uptime, response times, content changes, HTML validation or security testing. The service providers publish the IP addresses of the source systems so that companies can specifically allow access to their web sites. Since the number of these services is relatively small, it's not too difficult to find which one might give access to areas of a web site or web application that the public (and malicious people) should not be able to get to. The particular danger here is that the IP addresses might be excluded from monitoring and logging, and therefore even a diligent web site manager might not realise for example the uptime monitoring service is making unusual, or excessive, requests.

Although it is not likely a malicious person is using this "trusted" address unless routing has been compromised as well, problems can go undetected, from what might seem to be a legitimate source. The IP address may have been typed incorrectly, or worse, the restrictions/exceptions may not have been implemented correctly allowing more addresses to have the privileged access than intended. Not logging a user's session is privileged access.

Allow traffic through, but be very specific what is allowed and monitor what's going on. Review all the exceptions periodically. Be especially careful about anything that bypasses authentication (such as allowing a search engine to crawl restricted-access content) on an otherwise public site.

Posted on: 29 September 2009 at 10:18 hrs

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13 November 2008

A Cry for Help Which Made Me Want to Cry

E-consultancy.com has many excellent online marketing and e-commerce resources, and I read the blogs and forums regularly. The following posting appeared on the forum a couple of days ago:

Partial screen capture of posting to the e-consultancy.com forums asking 'Can anyone tell me if there is a way of finding out who hosts your website? We  need to find out who is hosting our website any help would be appreciated.'

This cry for help worried me. Although the forum replies were helpful, it did make me wonder how many other web site owners have no idea where their web site is hosted.

If this is really the case here, it probably means the owner doesn't have all the resources to rebuild the site elsewhere and possibly is without back-ups of the data. And what about the intellectual property ownership? It's something which all developers should be discussing with their customers. My first suggestion would have been to contact the development company. A cursory examination of the source code reveals:

Partial screen capture of page source code with a commented out hyperlink to the designers Osmodus

This company even showcases the site:

Partial screen capture showing the Gluttonous Gardener web site featured on the Osmodus portfolio pages

Now, we have no idea of the background and cannot guess if there is anything amiss. But the site is a card payment enabled e-commerce site, and surely the owner has had to comply with the Payment Card Industry (PCI) Security Standards Council's Data Security Standard (DSS)? Knowing where your web site is hosted would be one of the earlier things to discover.

Let's hope it's sorted soon.

Posted on: 13 November 2008 at 14:52 hrs

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15 August 2008

Is Your Web Site on Virtual Contaminated Land?

When we set up a web site, how much thought should we give to the previous use of the Internet Protocol (IP) address and domain name? Any previous use could spell disaster for a new web site.

When you buy a house your conveyancing solicitor will undertake local searches and review the Home Information Pack. For commercial transactions, organisations will usually undertake some form of due diligence checks including enquiring about previous uses of the site and adjoining properties using old maps and information from the local authority. No-one wants to inherit the liability for contaminated land, for example from a previous gas works, tanning plant or dye manufacturer that occupied the site.

Instead of chemical threats, web sites need some virtual due diligence, when setting up a new site or moving to a new hosting company or domain. It may also be an issue if your hosting company is changing their IP address ranges and this affects your servers. The threats are to your organisation's reputation if it becomes associated with something contrary to its beliefs, objectives or might upset its customers, clients or users. It could also lead to a lack of availability if the address is blocked by spam or web filtering gateways.

The Domain Name Service (DNS) is responsible for translating between human-friendly domain names (e.g. www.clerkendweller.com) and and machine-friendly IP addresses (e.g. 217.33.198.55). If a hosting company loses a client, they are very likely to re-allocate their web site's IP address to a new customer.

For a new IP address on your existing domain (e.g. a server move), my recommendation is to obtain details of:

  • How long the IP address has been allocated to the hosting company
  • All domains assigned to the IP address previously
  • Details of the organisations who own those domains
  • Check what is hosted on 'nearby' IP addresses i.e. in the same address block
  • Check what else is listed on the same domain name servers and the company who operates them

For a new web domain, check:

  • Ownership history
  • Current and prior internet usage (web, email, ftp, etc)
  • Check the IP addresses for both of these (as above)

Then, evaluate whether there is anything you might not want to be associated with or has been excluded by web/email filtering/firewall systems due to what it has been used for or the content it contained. Check other server IP addresses as well (e.g. your mail server) if this is changing as well. Also check what else is hosted on 'nearby' IP addresses in the same range.

For a new web domain, use tools like Netcraft, Site Advisor, The Way Back Machine and Google searches to investigate prior use. Check with suppliers of web filtering gateways and providers of reputational services whether the domains are blacklisted.

For mail, the Spam and Open Relay Blocking System (SORBS) and Spamhaus list potentially problematic spam sources and open mail relays. There are many more similar searchable spam lists listed at dr.moensted. You may also want to check whether Hotmail, GMail and AOL treat the IP or domain as a source of spam.

If you are purchasing an existing domain name, as opposed to registering one from scratch, check its previous and current use. Some companies serve advert pages for domains they own but are not allocated to a web site - be very wary of these.

If your hosting company won't help with this enquiry, go elsewhere.

Posted on: 15 August 2008 at 10:15 hrs

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