It's good to see different groups working together to improve security. This week another browser manufacturer announced future support for an initiative relating to Transport Layer Security (TLS, the successor to SSL).

HTTP Strict Transport Security (HSTS) describes a method for a web site to tell client browsers that they should only interact with it over secure transport, i.e. TLS Whilst there have been browser plugins which support this draft specification, support for HSTS was announced for v4 of Google Chrome in January, and last week for v4 of Mozilla Firefox. Hopefully Microsoft Internet Explorer 9 and ,a href="http://www.opera.com/">Opera will also adopt this.

Why is it important? Some attacks mean that TLS is vulnerable if there are redirects from non-TLS (e.g. http://www.example.com) to TLS (https://www.example.com) content. And if part, or all, of your web site is only meant to be accessed over SSL, HSTS should be implemented now, ready for mainstream adoption.

Further details are provided on the W3C page at Strict Transport Security (STS) and the draft IETF specification is at HTTP Strict Transport Security (HSTS).

A few weeks ago I mentioned two new research papers about the use of passwords on website. Another new paper from Microsoft Research and Harvard University discusses how to avoid, and protect web sites from, users selecting popular passwords.

The paper Popularity is Everything: A New Approach to Protecting Passwords from Statistical-Guessing Attacks describes online and offline threats and defences against the sue of common popular passwords.

Password implementation policies can be guided by legacy approaches and various standards, but as mentioned previously, economics plays a large part too. Following a much publicised successful brute force against Twitter accounts, the company increased its password requirements. But rather than forcing passwords to be more complex, they instead took the decision to prevent the use of 370 common passwords. Whilst the list is culturally-biased, due to other breaches, there is similar data from other sites (e.g. here and here). But how does banning popular passwords help, and if the lists of common passwords are known, does this matter?

Firstly I'll mention here a couple of typical online tools for determining password complexity:

• Password meter providing an indication of complexity
• Hammer of God providing an estimate of how long it would take to obtain the password using a brute force attack

Don't put your real passwords into these sites or any other checkers! But these types of tools do not take into account popularity (e.g. '123456') or common manipulations (e.g. is 'P@ssword' really that much more secure than 'password'?). If attackers try popular passwords first (i.e. a dictionary attack), the time to break into a user's account may be much shorter.

The research paper, which does include some mathematics, suggests that simple passwords should be allowed providing they are not subject to statistical guessing attacks and proposes attack detection methods.

Good reading and inspiration for password-based authentication systems. I'm off to the station now, to get a train to Newcastle which was cancelled last night.

PCI DSS and PA-DSS standards changes have been pre-announced by the Payment Card Industry Security Standards Council (PCI SCC).

Yesterday's announcement, which also includes notice of changes to PIN Transaction Security (PTS) requirements, provides a summary of the upcoming changes to v2.0 of PCI DSS and PA-DSS due in October 2010. Apart from increased alignment between the standards, the upcoming changes are meant to provide clarifications, additional guidance, new requirements and provide ways to improve organisations' flexibility to implement controls using a risk-based approach. There is also mention of a more forward-looking approach with guidance on managing evolving threats.

The indication that a risk-based approach is to be recommended for assessing vulnerabilities is a welcome change. This of course needs to be undertaken with a real regard of the risks to the business and its customers, clients and citizens, not just the data itself. The references to additional sources of good coding standards and vulnerabilities is encouraging.

The new standards are expected to be published on 28 October 2010 and will come into force on 1 January 2011. This will be quite a tight deadline for many operators to ensure they continue in compliance. The press release also includes details of upcoming meetings and webinars where additional information will be provided by the PCI SSC.

The UK Centre for the Protection of National Infrastructure (CPNI) have published new guidance on understanding and managing the risks from phishing and pharming.

Whilst most readers of this blog won't work on projects considered part of the national infrastructure, that doesn't mean you should ignore good, free advice.

The CPNI document discusses the threats and impacts (on employees, customers, clients and citizens), the modes of attack and possible countermeasures. I'm pleased to see that countermeasures to reduce the likelihood of successful attacks include both technical and cultural measures. Measures to mitigate the effects of successful attacks are also discussed.

Although some of the document is necessarily technical in places, the case studies in Appendix C should make sense to everyone. Remember, this is about business risk, not technical risk. The "I don't understand technical things" argument does not stand up.

Of course, assessing and implementing information security policies and controls is hardly ever simple or quick. But with the government's aim to reduce the number of different web sites this process may be a little easier. It's good to see such guidance, especially when the Central Office of Information (COI) has to date avoided the subject of security in its own web standards and guidelines. In view of the perception that the government isn't keeping up with threats (for example see the response to the petition to upgrade away from Internet Explorer 6), how are the CPNI phishing and pharming countermeasures being implemented by the government?

Knowledge about the degree to which the cultural countermeasures have been adopted within the government sector cannot be adequately measured from outside, and it would be good to see these included in work performed by the National Audit Office. Similarly most of the technical countermeasures would require privileged access to government networks (and permission!). However "use of SSL and TLS" and "signing of digital communications" should be easily observable, without doing any testing, from the outside world.

These two measures have security benefits beyond protection against phishing and pharming. They can assist citizens wanting to verify the identity of, and rely on the integrity of the information they see on what looks like a government web site, or receive in an official-looking email or other form of correspondence, perhaps during a national emergency. These types of event can attract themed phishing attacks for example. I haven't received any official government electronic communications recently apart from reminders from HMRC about tax deadlines and the like, so can't comment on how the sender and data integrity is verified. The tax reminders don't contain any sensitive data, and occur when there are known forthcoming business events or relate to actions undertaken by myself, so correctly don't need the same degree of verification.

But anyone can visit a web site, so what about those? Well, the CPNI web site appears to also be available over SSL/TLS as we'd expect. But, looking at https://www.direct.gov.uk using SSL (now more correctly called transport layer security, TLS) in the Chrome web browser, I was a bit surprised to see:

and this is the same for the prime minister's web site at https://www.number10.gov.uk/. Another possible primary governmental address is https://www.hmg.gov.uk which gives:

Maybe these have been deemed to be acceptable risks. But let's hope the other recommended countermeasures have been implemented.

Early last year I mentioned the security implications of the Web Content Accessibility Guidelines 2.0 and the scope for accessibility testing. I also spoke about whether an accessible web application be secure at the OWASP AppSec EU09 conference.

At that time, I found it fairly difficult to identify many web sites that were making WCAG 2.0 conformance claims.

The US Department of Justice is now seeking comments on proposed rule changes to the Americans with Disabilities Act that might make compliance to Level AA of WCAG 2.0 more widely mandated. A full analysis of the legal implications and timescales are presented on the Outlaw web site. As we see increased take-up in the US, it's likely similar levels of compliance will be required elsewhere.

In my conference presentation, I discussed how some security vulnerabilities could occur if WCAG 2.0 is implemented poorly.

Two great papers on web site password security were published this month. We are swamped with passwords and every daily activity is increasingly linked with an online version, which requires users to register to obtain some additional benefits. Every organisation, resource, activity and event encourages us to visit their own website and sign-up.

Firstly, in Where Do [Password] Security Policies Come From?, Dinei Florêncio and Cormac Herley of Microsoft Research discuss the password policies of 75 different web sites, in an effort to determine password strength requirements with other aspects such as size of site, assets protected, number of users and frequency of attacks.

The authors' findings suggest that none of these are the key factors, and in fact some of the largest sites, most attacked and with higher-value assets have the weakest password policies. The authors suggest stronger policies exist where organisations are more insulated from the consequences of poor usability, whereas online retailers and sites that rely on advertising revenues have to compete rigorously for users and traffic. The paper also discusses how strong passwords need to be, and how this is affected also by what attack methods you are considering (e.g. online vs. offline brute-force), and whether other security controls are implemented (e.g. account lock-out).

This idea of considering the whole password environment is taken further in The Password Thicket: Technical and Market Failures in Human Authentication on the Web by Joseph Bonneau and Sören Preibusch at the Cambridge University Computing Laboratory, and presented at this year's Economics of Information Security (WEIS 2010). Their study included 150 web sites looking at password implementations. the study looked more broadly at the protective measures used— not just complexity requirements—but whether these were applied consistently across the site's functionality (e.g. registration/enrolment, log-in/authentication, password change, password reset/recovery, log-out), encryption during transmission, storage of passwords in clear text, inclusion of passwords in emails, as well as protection from brute-force attacks.

The authors found that stricter security in one area was often undermined by weaknesses in another, suggesting that a lack of standards is harming security. The paper also discusses economic interpretations, such as how deploying passwords might be being used to justify collection of marketing data, and how password insecurity can be a negative externality.

Visa Inc has released a guide to Card Data Tokenization Best Practices.

The intention is to provide guidance on using non-sensitive surrogate values (tokens) as a proxy for card data (typically the primary account number or PAN) by merchants, vendors, service providers and acquirers. This in turn can reduce where card data exists, and therefore the scope for compliance with the Payment Card Industry Security Standards Council (PCISSC) Data Security Standard (DSS). The guidance joins other information in Visa'a Cardholder Information Security Program (CISP).

The guidance describes Visa's best practices for the tokenization system, token generation, token mapping, the card data vault (the secure repository that maps tokens to cardholder data), cryptographic key management and the management of historical data.

However the guidance may not generally accepted and is being debated here and here, especially with regards to reversibility of the process and the use of salts when hashing, but Visa are seeking feedback on this first version, and have asked for responses by 31 August 2010 to be sent by email to inforisk@visa.com.

Knowledge of application context is used routinely in mobile applications—for example sensing a user's context (e.g. location and physical actions, time, etc), reducing network usage during periods of inactivity and designing for users. But how does this idea transfer to the server?

I almost called this environmental awareness, but didn't want to cause confusion with discussions about network/server environments. By 'situational awareness' I mean awareness of factors external to the application that might be used to affect its behaviour. In my talk this week about application intrusion detection, I will be discussing how an aspect such as the general risk level to an organisation/application might be used to alter an application's actions (e.g. amount of logging, attack detection thresholds). But this awareness, can be used beyond attacker detection and response.

Information is knowledge and additional awareness of external factors can be used to control changes to the application. An adaptive application can learn change in response to outside factors. And no, I don't mean displaying an intrusive and annoying paperclip that says "It looks like you're writing a letter". Apart from standard functionality the user sees, some ways your application may already be doing this are:

• customising content based on:
  • geo-location information
  • user preferences
  • device type (e.g. mobile), browser and screen resolution
  • typical user behaviour
• implementation of additional delays for failed attempts at authentication
• use of reputation-based systems
• displaying the number/identities of active/logged-in users
• detecting usage of the application by users from a different location than they had used previously (e.g. IP address)
• showing advertising based on users' behavioural characteristics.

But what else can be done? I remember chatting with someone during an unexpected period of severe weather which had disrupted travel in south-east England one morning. They had explained that in situations like this when their call centre was under staffed, they had procedures in place to reduce the length of each customer call, by shortening their own scripts taking out offers for helping with anything else and cross-selling/up-selling. The dialogue script was adapted to the situation. A web application could respond in a similar way during increasing, and higher periods of demand, to increase availability:

• switch to more static content (e.g. change the home page to static HTML rather than a scripted dynamic page)
• swap to lower bandwidth assets (e.g. display photographs instead of videos, use lower resolution photos)
• use third-party servers for some content (e.g. video on YouTube)
• reduce the size of pages and number of page elements by dropping out non-core material (e.g. promotional items, banners)
• increase caching
• delay non-core server intensive activities (e.g. management report generation)
• provide links to printable forms to divert some or all users of a particular online service.

Similarly, if a local (e.g. dynamic PDF creation or chart generation), back-office (e.g. data archive) or third-party service (e.g. payment authorisation, address look-up) is detected as running slowly or has become unavailable, some of the following may be possible:

• switch to cached data
• add a queue to access the function
• slow down the speed at which users can undertake the function
• offer alternative (quicker) ways to complete the transaction
• take the service offline, but offer to email users back when it is available again.

Similar changes could occur in advance of, or during, known scheduled application maintenance periods:

• advanced warning notices to users
• timed count-down to function or application shutdown
• preventing users beginning new tasks which might not be able to be completed before the shutdown
• ability for users to request notification that the service is back up.

The important thing (remember "clippy") is not to change the user experience too noticeably, and where there is a significant change (e.g. download the form instead of doing it online), provide a time-stamped explanation of the change and reasons.

These measures all bring complexity, and it is important they do not introduce additional vulnerabilities to the application. The problems are quite likely to be in authentication, authorisation and session management and need to be identified during security specification and verification processes. The effect on data integrity, including accuracy, also needs to be considered. But the measures are worth considering where the alternative is additional standby staff and increased usage of other channels.

Fed up with false positives when trying to detect malicious users with network intrusion detection systems (IDS)? Application intrusion detection is the way to go.

Like an advanced robot, applications can build in security protection, detection and response.

Next Thursday 15th July 2010, I will be presenting "Real Time Application Attack Detection and Response" at the next OWASP meeting in London. Like all OWASP chapter meetings, the event is free but prior registration is required.

I will talk about how advanced attackers probe and try to exploit applications, how some common defences against these attacks are of no use, and why we need to use protection that:

• understands the application
• understands normal vs. suspicious use
• can identify and shut down attackers in real time.

Is this possible? Yes. AppSensor specifies how application-based detection points can be used to stop attackers. I will also describe how project leader Michael Coates has demonstrated how real web sites can deploy such measures in practice to protect an application against automated scanners, advanced attackers and build in protection against application worms.

Arrive from 17:30 hrs since the talks start promptly at 18:00. Hope to see you there.

Yesterday, the UK Information Commissioner's Office (ICO) launched their Personal Information Online Code of Practice.

The new code is available online as an eBook together with associated guidance for individuals Protecting Your Personal Information Online. Hopefully the code will also be available as a standalone PDF for offline use and in print.

The Personal Information Online Code of Practice has been improved substantially since the draft for consultation was issued in December. The code describes the benefits of protecting personal information including increased trust, reduced reputational risk, better take-up of services, reduced risk of data breaches and associated enforcement action, improved competitive advantage, increased quality of data and decreased customer/client/citizen support costs.

I am pleased to see so many practical tips tied to real-world examples such as whether IP addresses are personal data (answer: probably). It is difficult to get the balance of detail and readability correct, but I think this document will hit the mark for many busy web site owners.

The code points to other matters that should be considered (e.g. risk assessments), but correctly doesn't details precisely how these are undertaken.

Update 9th July 2010: The Personal Information Online Code of Practice is now available both as a PDF and in print on request.