Pre-loading HSTS for sibling domains through this one weird trick

The vast majority of websites now support encrypted connections over HTTPS. This prevents eavesdroppers from monitoring or tampering with people’s web activity and is great for privacy. However, HTTPS is optional, and all browsers still support plain unsecured HTTP for when a website doesn’t support encryption. HTTP is commonly the default, and even when it’s not, there’s often no warning when access to a site falls back to using HTTP.

The optional nature of HTTPS is its weakness and can be exploited through tools, like sslstrip, which force browsers to fall back to HTTP, allowing the attacker to eavesdrop or tamper with the connection. In response to this weakness, HTTP Strict Transport Security (HSTS) was created. HSTS allows a website to tell the browser that only HTTPS should be used in future. As long as someone visits an HSTS-enabled website one time over a trustworthy Internet connection, their browser will refuse any attempt to fall back to HTTP. If that person then uses a malicious Internet connection, the worst that can happen is access to that website will be blocked; tampering and eavesdropping are prevented.

Still, someone needs to visit the website once before an HSTS setting is recorded, leaving a window of opportunity for an attacker. The sooner a website can get its HSTS setting recorded, the better. One aspect of HSTS that helps is that a website can indicate that not only should it be HSTS enabled, but that all subdomains are too. For example, planet.wikimedia.org can say that the subdomain en.planet.wikimedia.org is HSTS enabled. However, planet.wikimedia.org can’t say that commons.wikimedia.org is HSTS enabled because they are sibling domains. As a result, someone would need to visit both commons.wikimedia.org and planet.wikimedia.org before both websites would be protected.

What if HSTS could be applied to sibling domains and not just subdomains? That would allow one domain to protect accesses to another. The HSTS specification explicitly excludes this feature, for a good reason: discovering whether two sibling domains are run by the same organisation is fraught with difficulty. However, it turns out there’s a way to “trick” browsers into pre-loading HSTS status for sibling domains.

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Still treating users as the enemy: entrapment and the escalating nastiness of simulated phishing campaigns

Three years ago, we made the case against phishing your own employees through simulated phishing campaigns. They do little to improve security: click rates tend to be reduced (temporarily) but not to zero – and each remaining click can enable an attack. They also have a hidden cost in terms of productivity – employees have to spend time processing more emails that are not relevant to their work, and then spend more time pondering whether to act on emails. In a recent paper, Melanie Volkamer and colleagues provided a detailed listing of the pros and cons from the perspectives of security, human factors and law. One of the legal risks was finding yourself in court with one of the 600-pound digital enterprise gorillas for trademark infringement – Facebook objected to their trademark and domain being impersonated. They also likely don’t want their brand to be used in attacks because, contrary to what some vendors tell you, being tricked by your employer is not a pleasant experience. Negative emotions experienced with an event often transfer to anyone or anything associated with it – and negative emotions are not what you want associated with your brand if your business depends on keeping billions of users engaging with your services as often as possible.

Recent tactics employed by the providers of phishing campaigns can only be described as entrapment – to “demonstrate” the need for their services, they create messages that almost everyone will click on. Employees of the Chicago Tribune and GoDaddy, for instance, received emails promising bonuses. Employees had hope of extra pay raised and then cruelly dashed, and on top, were hectored for being careless about phishing. Some employees vented their rage publicly on Twitter, and the companies involved apologised. The negative publicity may eventually be forgotten, but the resentment of employees feeling not only tricked but humiliated and betrayed, will not fade any time soon. The increasing nastiness of entrapment has seen employees targeted with promises of COVID vaccinations from employers – who then find themselves being ridiculed for their gullibility instead of lauded for their willingness to help.

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The role of usability, power dynamics, and incentives in dispute resolutions around computer evidence

As evidence produced by a computer is often used in court cases, there are necessarily presumptions about the correct operation of the computer that produces it. At present, based on a 1997 paper by the Law Commission, it is assumed that a computer operated correctly unless there is explicit evidence to the contrary.

The recent Post Office trial (previously mentioned on Bentham’s Gaze) has made clear, if previous cases had not, that this assumption is flawed. After all, computers and the software they run are never perfect.

This blog post discusses a recent invited paper published in the Digital Evidence and Electronic Signature Law Review titled The Law Commission presumption concerning the dependability of computer evidence. The authors of the paper, collectively referred to as LLTT, are Peter Bernard Ladkin, Bev Littlewood, Harold Thimbleby and Martyn Thomas.

LLTT examine the basis for the presumption that a computer operated correctly unless there is explicit evidence to the contrary. They explain why the Law Commission’s belief in Colin Tapper’s statement in 1991 that “most computer error is either immediately detectable or results from error in the data entered into the machine” is flawed. Not only can computers be assumed to have bugs (including undiscovered bugs) but the occurrence of a bug may not be noticeable.

LLTT put forward three recommendations. First, a presumption that any particular computer system failure is not caused by software is not justified, even for software that has previously been shown to be very reliable. Second, evidence of previous computer failure undermines a presumption of current proper functioning. Third, the fact that a class of failures has not happened before is not a reason for assuming it cannot occur.

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By revisiting security training through economics principles, organisations can navigate how to support effective security behaviour change

Here I describe analysis by myself and colleagues Albesë Demjaha and David Pym at UCL, which originally appeared at the STAST workshop in late 2019 (where it was awarded best paper). The work was the basis for a talk I gave at Cambridge Computer Laboratory earlier this week (I thank Alice Hutchings and the Security Group for hosting the talk, as it was also an opportunity to consider this work alongside themes raised in our recent eCrime 2019 paper).

Secure behaviour in organisations

Both research and practice have shown that security behaviours, encapsulated in policy and advised in organisations, may not be adopted by employees. Employees may not see how advice applies to them, find it difficult to follow, or regard the expectations as unrealistic. Employees may, as a consequence, create their own alternative behaviours as an effort to approximate secure working (rather than totally abandoning security). Organisational support can then be critical to whether secure practices persist. Economics principles can be applied to explain how complex systems such as these behave the way they do, and so here we focus on informing an overarching goal to:

Provide better support for ‘good enough’ security-related decisions, by individuals within an organization, that best approximate secure behaviours under constraints, such as limited time or knowledge.

Traditional economics assumes decision-makers are rational, and that they are equipped with the capabilities and resources to make the decision which will be most beneficial for them. However, people have reasons, motivations, and goals when deciding to do something — whether they do it well or badly, they do engage in thinking and reasoning when making a decision. We must capture how the decision-making process looks for the employee, as a bounded agent with limited resources and knowledge to make the best choice. This process is more realistically represented in behavioural economics. And yet, behaviour intervention programmes mix elements of both of these areas of economics. It is by considering these principles in tandem that we explore a more constructive approach to decision-support in organisations.

Contradictions in current practice

A bounded agent often settles for a satisfactory decision, by satisficing rather than optimising. For example, the agent can turn to ‘rules of thumb’ and make ad-hoc decisions, based on a quick evaluation of perceived probability, costs, gains, and losses. We can already imagine how these restrictions may play out in a busy workplace. This leads us toward identifying those points of engagement at which employees ought to be supported, in order to avoid poor choices.

Continue reading By revisiting security training through economics principles, organisations can navigate how to support effective security behaviour change

UK Parliament on protecting consumers from economic crime

On Friday, the UK House of Commons Treasury Committee published their report on the consumer perspective of economic crime. I’ve frequently addressed this topic in my research, as well as here on Bentham’s Gaze, so I’m pleased to see several recommendations of the committee match what myself and colleagues have proposed. In other respects, the report could have gone further, so as well as discussing the positive aspects of the report, I would also like to suggest what more could be done to reduce economic crime and protect its victims.

Irrevocable payments are the wrong default

Transfers between UK bank accounts will generally use the Faster Payment System (FPS), where money will immediately show up in the recipient account. FPS transfers cannot be revoked, even in the case of fraud. This characteristic protects banks because if fraudulently obtained funds leave the banking system, the bank receiving the transfer has no obligation to reimburse the victim.

In contrast, the clearing system for paper cheques permits payments to be revoked for a few days after the funds appeared in the recipient account, should there have been a fraud. This period allows customers to quickly make use of funds they receive, while still giving a window of opportunity for banks and customers to identify and prevent fraud. There’s no reason why this same revocation window could not be applied to fully electronic payment systems like FPS.

In my submissions to consultations on how to prevent push payment scams, I argued that irrevocable payments are the wrong default, and transfers should be possible to reverse in cases of fraud. The same argument applies to consumer-oriented cryptocurrencies like Libra. I’m pleased to see that the Treasury Committee agrees and they have recommended that when a customer sends money to an account for the first time, that transfer be revocable for 24 hours.

Introducing Confirmation of Payee, finally

The banking industry has been planning on launching the Confirmation of Payee system to check if the name of the recipient of a transfer matches what the customer sending money thinks. The committee is clearly frustrated with delays on deploying this system, first promised for September 2018 but since slipped to March 2020. Confirmation of Payee will be a helpful tool for customers to help avoid certain frauds. Still, I’m pleased the committee also recognise it’s limitations and that the “onus will always be on financial firms to develop further methods and technologies to keep up with fraudsters.” It is for this reason that I argued that a bank showing a customer a Confirmation of Payee mismatch should not be a sufficient condition to hold customers liable for fraud, and the push-payment scam reimbursement scheme is wrong to do so. It doesn’t look like the committee is asking for the situation to be changed though.

Continue reading UK Parliament on protecting consumers from economic crime

Beyond Regulators’ Concerns, Facebook’s Libra Cryptocurrency Faces another Big Challenge: The Risk of Fraud

Facebook has attracted attention through the announcement of their blockchain-based payment network, Libra. This won’t be the first payment system Facebook has launched, but what makes Facebook’s Libra distinctive is that rather than transferring Euros or dollars, the network is designed for a new cryptocurrency, also called Libra. This currency is backed by a reserve of nationally-issued currencies, and so Facebook hopes it will avoid the high volatility of cryptocurrencies like Bitcoin. As a result, Libra won’t be attractive to currency speculators, but Facebook hopes that it will, therefore, be useful for its stated goal – to be a “simple global currency and financial infrastructure that empowers billions of people.”

Reducing currency volatility is only one step towards meeting this goal of scaling cryptocurrencies to billions of users. The Libra blockchain design addresses how the network can maintain the high throughput and low transaction fees needed to compete with existing payment networks like Visa or MasterCard. However, a question that is equally important but as yet unanswered is how Facebook will develop a secure authentication and fraud prevention system that can scale to billions of users while maintaining good usability and low cost.

Facebook designed the Libra network, but in contrast to traditional payment networks, the Libra network is open. Anyone can send transactions through the network, and anyone can write programs (known as “smart contracts”) that control how, and under what conditions, funds can move between Libra accounts. To comply with anti-money-laundering regulations, Know Your Customer (KYC) checks will be performed, but only when Libra enters or leaves the network through exchanges. Transactions moving funds within the network should be accepted if they meet the criteria set out in the applicable smart contract, regardless of who sent them.

The Libra network isn’t even restricted to transactions transferring the Libra currency. Facebook has explicitly designed the Libra blockchain to make it easy for anyone to implement their own currency and benefit from the same technical facilities that Facebook designed for its currency. Other blockchains have tried this. For example, Ethereum has spawned hundreds of special-purpose currencies. But programming a smart contract to implement a new currency is difficult, and errors can be costly. The programming language for smart contracts within the Libra network is designed to help developers avoid some of the most common mistakes.

Facebook’s Libra and Securing the Calibra Wallet

There’s more to setting up an effective currency than just the technology: regulatory compliance, a network of exchanges, and monetary policy are essential. Facebook, through setting up the Libra Association, is focusing its efforts here solely on the Libra currency. The widespread expectation is, therefore, at least initially, the Libra cryptocurrency will be the dominant usage of the network, and most users will send and receive funds through the Calibra wallet smartphone app, developed by a Facebook subsidiary. From the perspective of the vast majority of the world, the Calibra wallet will be synonymous with Facebook’s Libra, and so damage to trust in Calibra will damage the reputation of Libra as a whole.

Continue reading Beyond Regulators’ Concerns, Facebook’s Libra Cryptocurrency Faces another Big Challenge: The Risk of Fraud

Next version of Android might introduce new security risks for online banking, 2FA, and more

Google is preparing new functionality for Android that will allow apps to retrieve and auto-fill security codes from SMS. Last year Apple introduced a similar feature to iOS and macOS, for which we discovered security risks for online banking, two-factor authentication, and other services. Will Google come up with a better design? In this post, we analyse what we know about this feature so far. 


The latest developer beta of Google Play Services (18.7.13 beta) contains code fragments that show a new Android permission to automatically retrieve verification codes from text messages. This feature has not yet been fully implemented, but the available code allows for some analysis and early evaluation for possible security risks, akin to similar risks we demonstrated in 2018 for the Security Code AutoFill feature in iOS and macOS.

Background

It seems that Google is updating the “Autofill Framework”, introduced with Android 8.0 in 2017, to include the new functionality. Previously, this framework’s sole purpose was to support the autofill functionality of password managers in Android apps and websites. The code fragments of this new feature reveal the names and descriptions of the associated system setting and corresponding runtime permission requests, shown below.

A screenshot of an Android phone.
The likely UI of the new setting in Android to enable/disable SMS Code Auto-fill.
The picture of an Android runtime permission request.
The likely UI of the new runtime permission request in Android to deny or allow an application’s access to the SMS Code Auto-fill feature.

Continue reading Next version of Android might introduce new security risks for online banking, 2FA, and more

Confirmation of Payee is coming, but will it protect bank customers from fraud?

The Payment System Regulator (PSR) has just announced that the UK’s six largest banks must check whether the name of the recipient of a transfer matches what the sender thinks. This new feature should help address a security loophole in online payments: the name of the recipient of transfers is ignored, contrary to expectations and unlike cheques. This improved security should make some fraud more difficult, but banks must be prevented from exploiting the change to unfairly shift the liability of the remaining crime to the victims.

The PSR’s target is for checks to be fully implemented by March 2020, somewhat later than their initial promise to Parliament of September 2018 and subsequent target of July 2019. The new proposal, known as Confirmation of Payee, also only covers the six largest banking groups, but this should cover 90% of transfers. Its goal is to defend against criminals who trick victims into transferring funds under the false pretence that the money is going to the victim’s new account, whereas it is really going to the criminal. The losses from such fraud, known as push payment scams, are often life-changing, resulting in misery for the victims.

Checks on the recipient name will make this particular scam harder, so while unlikely to prevent all types of push payment scams they will hopefully force criminals to adopt strategies that are easier to prevent. The risk that consumer representatives and regulators will need to watch out for is that these new security measures could result in victims being unfairly held liable. This scenario is, unfortunately, likely because the voluntary consumer protection code for push payment scams excuses the bank from liability if they show the customer a Confirmation of Payee warning.

Warning fatigue and misaligned incentives

In my response to the consultation over this consumer protection code, I raised the issue of “warning fatigue” – that customers will be shown many irrelevant warnings while they do online banking and this reduces the likelihood that customers will notice important ones. Even Confirmation of Payee warnings will frequently be wrong, such as if the recipient’s bank account is under a different name to what the sender expects. If the two names are very dissimilar, the sender won’t be given more details but if the name entered is close to the name in bank records the sender should be told what the correct one is and asked to compare.

Continue reading Confirmation of Payee is coming, but will it protect bank customers from fraud?

How Accidental Data Breaches can be Facilitated by Windows 10 and macOS Mojave

Inadequate user interface designs in Windows 10 and macOS Mojave can cause accidental data breaches through inconsistent language, insecure default options, and unclear or incomprehensible information. Users could accidentally leak sensitive personal data. Data controllers in companies might be unknowingly non-compliant with the GDPR’s legal obligations for data erasure.

At the upcoming Annual Privacy Forum 2019 in Rome, I will be presenting the results of a recent study conducted with my colleague Mark Warner, exploring the inadequate design of user interfaces (UI) as a contributing factor in accidental data breaches from USB memory sticks. The paper titled “Fight to be Forgotten: Exploring the Efficacy of Data Erasure in Popular Operating Systems” will be published in the conference proceedings at a later date but the accepted version is available now.

Privacy and security risks from decommissioned memory chips

The process of decommissioning memory chips (e.g. USB sticks, hard drives, and memory cards) can create risks for data protection. Researchers have repeatedly found sensitive data on devices they acquired from second-hand markets. Sometimes this data was from the previous owners, other times from third persons. In some cases, highly sensitive data from vulnerable people were found, e.g. Jones et al. found videos of children at a high school in the UK on a second-hand USB stick.

Data found this way had frequently been deleted but not erased, creating the risk that any tech-savvy future owner could access it using legally available, free to download software (e.g., FTK Imager Lite 3.4.3.3). Findings from these studies also indicate the previous owners’ intentions to erase these files and prevent future access by unauthorised individuals, and their failure to sufficiently do so. Moreover, these risks likely extend from the second-hand market to recycled memory chips – a practice encouraged under Directive 2012/19/EU on ‘waste electrical and electronic equipment’.

The implications for data security and data protection are substantial. End-users and companies alike could accidentally cause breaches of sensitive personal data of themselves or their customers. The protection of personal data is enshrined in Article 8 of the Charter of Fundamental Rights of the European Union, and the General Data Protection Regulation (GDPR) lays down rules and regulation for the protection of this fundamental right. For example, data processors could find themselves inadvertently in violation of Article 17 GDPR Right to Erasure (‘right to be forgotten’) despite their best intentions if they failed to erase a customer’s personal data – independent of whether that data was breached or not.

Seemingly minor design choices, the potential for major implications

The indication that people might fail to properly erase files from storage, despite their apparent intention to do so, is a strong sign of system failure. We know since more than twenty years that unintentional failure of users at a task is often caused by the way in which [these] mechanisms are implemented, and users’ lack of knowledge. In our case, these mechanisms are – for most users – the UI of Windows and macOS. When investigating these mechanisms, we found seemingly minor design choices that might facilitate unintentional data breaches. A few examples are shown below and are expanded upon in the full publication of our work.

Continue reading How Accidental Data Breaches can be Facilitated by Windows 10 and macOS Mojave

UK Faster Payment System Prompts Changes to Fraud Regulation

Banking transactions are rapidly moving online, offering convenience to customers and allowing banks to close branches and re-focus on marketing more profitable financial products. At the same time, new payment methods, like the UK’s Faster Payment System, make transactions irrevocable within hours, not days, and so let recipients make use of funds immediately.

However, these changes have also created a new opportunity for fraud schemes that trick victims into performing a transaction under false pretences. For example, a criminal might call a bank customer, tell them that their account has been compromised, and help them to transfer money to a supposedly safe account that is actually under the criminal’s control. Losses in the UK from this type of fraud were £145.4 million during the first half of 2018 but importantly for the public, such frauds fall outside of existing consumer protection rules, leaving the customer liable for sometimes life-changing amounts.

The human cost behind this epidemic has persuaded regulators to do more to protect customers and create incentives for banks to do a better job at preventing the fraud. These measures are coming sooner than UK Finance – the trade association for UK based banking payments and cards businesses – would like, but during questioning by the House of Commons Treasury Committee, their Chief Executive conceded that change is coming. They now focus on who will reimburse customers who have been defrauded through no fault of their own. Who picks up the bill will depend not just on how good fraud prevention measures are, but how effectively banks can demonstrate this fact.

UK Faster Payment Creates an Opportunity for Social Engineering Attacks

One factor that contributed to the new type of fraud is that online interactions lack the usual cues that help customers tell whether a bank is genuine. Criminals use sophisticated social engineering attacks that create a sense of urgency, combined with information gathered about the customer through illicit means, to convince even diligent victims that it could only be their own bank calling. These techniques, combined with the newly irrevocable payment system, create an ideal situation for criminals.

Continue reading UK Faster Payment System Prompts Changes to Fraud Regulation