The UK's Centre for the Protection of National Infrastructure (CPNI) has updated its guidance on protecting business applications with the publication this month of a new document on developing and implementing secure web applications.

Development and Implementation of Secure Web Applications is a well-written and digestible 81-page A4 document arranged in seven main sections:

• Introduction to web application security
• General aspects of web application security
• Access handling (authentication, session management and access control)
• Injection flaws
• Application users and security
• Thick client security
• Preparing the infrastructure

It appears to replace the good, but somewhat dated document "Briefing 10/2006 - Secure web Applications - Development, Installation and Security Testing" created by their predecessor National Infrastructure Security Co-ordination Centre (NISCC), and issued in April 2006. The new document is more compact and focused, and I think I prefer it. Yes of course it is more up-to-date, and while it would be possible to argue why some things are included and not others, these others things tend to be explained further in the references. It's clear there is considerable overlap with information from OWASP and the Microsoft SDL, but I'm sure the reverse is true to an extent too.

It is very encouraging CPNI have taken the time to produce an updated document, but that probably reflects the types of risks facing their audience. I am especially pleased to see the section on infrastructure, since application security cannot be an island on its own. I would say the guidance is probably on the medium-to-heavy weight side of advice, but that is probably appropriate for critical national infrastructure, and the document does discuss threat modelling initially. It might seem overwhelming to some organisations new to the subject, and that might need some help on what to do first.

I think the document could perhaps do with more cross-referencing to additional information resources elsewhere. Yes, documents can always be improved, and I am sure we will find niggles and faults with use, but threats evolve and so does our knowledge.

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.

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).
  • use resources such as the OWASP Top Ten and WASC Threat Classification
  • build security requirements into future developments
• 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?

The news that a the UK hosting company VAServ lost 100,000 web sites all at once is devastating for the organisations involved. It appears that many cannot be recovered and a considerable number do not have recent backups.

From the temporary status page dated 10th June:

The event was widely reported:

• Webhost Hack Wipes Out Data for 100,000 Sites
• Webhost Denies Poor Passwords Led to Catastrophic Hack
• U.K. Web Hoster, Customers Scramble After Attack Deletes 100,000 Sites

Particularly sobering is the news that the CEO of LxLabs, implicated as the developers of the software that was hacked, has committed suicide:

• LxLabs boss found hanged after vuln[erability] wipes websites
• Web Hacking Incident Database (WHID) 2009-45: Outcome: Death

Even if you don't have a formal disaster recovery plan, at least make sure you have backups of all your site code, database and other data.

Hardening the underlying server operating system is an important fundamental task to help protect your web applications.

For example, the Payment Card Industry Data Security Standard (PCIDSS) requirement 2.2 states:

Two United States organisations producing guidance in this field are:

• Security Configuration Benchmarks from the Center for Internet Security (CIS)
• Security Content Automation Protocol (SCAP) Checklists from the National Institute of Standards and Technology (NIST) Computer Security Division (CSD)

These are detailed documents and all the recommendations may not be appropriate for your own situation.

This week a friend contacted me about his business website. It seemed his company had paid for both a .co.uk and .com domain name, but the latter was not currently mapped to her site.

It seems the web developer wasn't being co-operative and she was asking for some advice. It appeared that neither domain were registered in my friend's company's name—both named the developers. This makes things much more difficult if the developers are slow to respond to change requests, or fail to renew your domains, or you fall out with them or they go out of business.

But I came across another example on Wednesday. I had to drive through London and later in the day I went to pay the £8.00 charge using the congestion charge online payment service from Transport for London.

I looked at the SSL certificate's details and was very surprised to see the organisation named on the certificate (known as the distinguished name field for organization) was not "Transport for London" but "Cobweb Solutions Ltd", presumably this company.

Whilst this may not be contrary to the SSL Protocol Specification, it is contrary to expectations and good practice. If this were a retail website (where you choose to buy rather than being obligated to pay!), would a cautious potential customer trust the site? The information has also given away vital clues to a malicious user on the software development company and thus perhaps possible approaches to breach the system. Cobweb Solutions' own site has a shopping basket/e-commerce system that has a similarly attributed secure certificate:

Like domain names, your own website SSL certificates, regardless of SSL certificate type should be in your own organisation's name, not anyone else's. In fact this also usually makes the proces of purchasing a certificate simpler.

On my friend's domain name issue, she has contacted the relevant domain name registrars using their disputes process to ask for the details to be updated. She is also checking whose name is on the web hosting contract.

The first stage of attack is reconnaissance. Therefore don't give the enemy information they shouldn't have.

I photographed this public information screen at the weekend. It looks like it's part-way through being commissioned, but it was displaying important network information.

In this case I suspect the information isn't particularly helpful to someone who wants to display their own messages instead of the official ones, but it is leaking information about how the system works. This particular installation probably isn't part of the critical national infrastructure, but is any more case being taken there?

Web sites often give away too much information in their error messages, filenames, source code, headers and cookies. This information can be used to help compromise the site.