Security Engineering. Ross Anderson

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СКАЧАТЬ banks took to claiming that it's your identity that's been stolen rather than their money [1730]. There is less of that liability dumping now, but the FBI still records much cybercrime as ‘identity theft’ which helps keep it out of the mainstream US crime statistics.

      The card fraud ecosystem is now fairly stable. Surveys in 2011 and 2019 show that while card fraud doubled over the decade, the loss fell slightly as a percentage of transaction value [91, 92]; the system has been getting more efficient as it grows. Many card numbers are harvested in hacking attacks on retailers, which can be very expensive for them once they've paid to notify affected customers and reimburse banks for reissued cards. As with the criminal infrastructure, the total costs may be easily two orders of magnitude greater than anything the criminals actually get away with.

      Attacks on online banking ramped up in 2005 with the arrival of large-scale phishing attacks; emails that seemed to come from banks drove customers to imitation bank websites that stole their passwords. The banks responded with techniques such as two-factor authentication, or the low-cost substitute of asking for only a few letters of the password at a time; the crooks' response, from about 2009, has been credential-stealing malware. Zeus and later Trojans lurk on a PC until the user logs on to a bank whose website they recognise; they then make payments to mule accounts and hide their activity from the user – the so-called ‘man-in-the-browser attack’. (Some Trojans even connect in real time to a human operator.) The crooks behind the Zeus and later the Dridex banking malware were named and indicted by US investigators in December 2019, and accused of stealing some $100m, but they remain at liberty in Russia [796]. Other gangs have been broken up and people arrested for such scams, which continue to net in the hundreds of millions to low billions a year worldwide.

      Firms also have to pay attention to business email compromise, where a crook compromises a business email account and tells a customer that their bank account number has changed; or where the crook impersonates the CEO and orders a financial controller to make a payment; and social engineering attacks by people pretending to be from your bank who talk you into releasing a code to authorise a payment. Most targeted attacks on company payment systems can in theory be prevented by the control procedures that most large firms already have, and so the typical target is a badly-run large firm, or a medium-sized firm with enough money to be worth stealing but not enough control to lock everything down.

      I'll discuss the technicalities of such frauds in Chapter 12, along with a growing number of crimes that directly affect only banks, their regulators and their retail customers. I'll also discuss cryptocurrencies, which facilitate cybercrimes from ransomware to stock frauds, in Chapter 20.

      2.3.3 Sectoral cybercrime ecosystems

      A number of sectors other than banking have their own established cybercrime scenes. One example is travel fraud. There's a whole ecosystem of people who sell fraudulently obtained air tickets, which are sometimes simply bought with stolen credit card numbers, sometimes obtained directly by manipulating or hacking the systems of travel agents or airlines, sometimes booked by corrupt staff at these firms, and sometimes scammed from the public directly by stealing their air miles. The resulting cut-price tickets are sold directly using spam or through various affiliate marketing scams. Some of the passengers who use them to fly know they're dubious, while others are dupes – which makes it hard to deal with the problem just by arresting people at the boarding gate. (The scammers also supply tickets at the last minute, so that the alarms are usually too late.) For an account and analysis of travel fraud, see Hutchings [938]. An increasing number of other business sectors are acquiring their own dark side, and I will touch on some of them in later chapters.

      2.3.4 Internal attacks

      Fraud by insiders has been an issue since businesses started hiring people. Employees cheat the firm, partners cheat each other, and firms cheat their shareholders. The main defence is bookkeeping. The invention of double-entry bookkeeping, of which our earliest records are from the Cairo of a thousand years ago, enabled businesses to scale up beyond the family that owned them. This whole ecosystem is evolving as technology does, and its design is driven by the Big Four accounting firms who make demands on their audit clients that in turn drive the development of accounting software and the supporting security mechanisms. I discuss all this at length in Chapter 12. There are also inside attacks involving whistleblowing, which I discuss below.

2.3.5 CEO crimes

Companies attack each other, and their customers too. From the 1990s, printer vendors have used cryptography to lock their customers in to using proprietary ink cartridges, as I describe in section 24.6, while companies selling refills have been breaking the crypto. Games console makers have been playing exactly the same game with aftermarket vendors. The use of cryptography for accessory control is now pervasive, being found even on water filter cartridges in fridges [1073]. Many customers find this annoying and try to circumvent the controls. The US courts decided in the Lexmark v SCC case that this was fine: the printer vendor Lexmark sued SCC, a company that sold clones of its security chips to independent ink vendors, but lost. So the incumbent can now hire the best cryptographers they can find to lock their products, while the challenger can hire the best cryptanalysts they can find to unlock them – and customers can hack them any way they can. Here, the conflict is legal and open. As with state actors, corporates sometimes assemble teams with multiple PhDs, millions of dollars in funding, and capital assets such as electron microscopes¹³. We discuss this in greater detail later in section 24.6.

      Not all corporate attacks are conducted as openly. Perhaps the best-known covert hack was by Volkswagen on the EU and US emissions testing schemes; diesel engines sold in cars were programmed to run cleanly if they detected the standard emission test conditions, and efficiently otherwise. For this, the CEO of VW was fired and indicted in the USA (to which Germany won't extradite him), while the CEO of Audi was fired and jailed in Germany [1086]. VW has set aside €25bn to cover criminal and civil fines and compensation. Other carmakers were cheating too; Daimler was fined €860m in Europe in 2019 [1468], and in 2020 reached a US settlement consisting of a fine of $1.5bn from four government agencies plus a class action of $700m [1859]. Settlements for other manufacturers and other countries are in the pipeline.

      Sometimes products are designed to break whole classes of protection system, an example being the overlay SIM cards described later in Chapter 12. These are SIM cards with two sides and only 160 microns thick, which you stick on top of the SIM card in your phone to provide a second root of trust; they were designed to enable people in China to defeat the high roaming charges of the early 2010s. The overlay SIM essentially does a man-in-the-middle attack on the real SIM, and can be programmed in Javacard. A side-effect is that such SIMs make it really easy to do some types of bank fraud.

      So when putting together the threat model for your system, stop and think what capable motivated opponents you might have among your competitors, or among firms competing with suppliers on which products you depend. The obvious attacks include industrial espionage, but nowadays it's much more complex than that.

      2.3.6 Whistleblowers

      Intelligence agencies, and secretive firms, can get obsessive about ‘the insider threat’. But in 2018, Barclays Bank's CEO was fined £642,000 and ordered to repay £500,000 of his bonus for attempting to trace a whistleblower in the bank [698]. So let's turn it round and look at it from the other perspective – that of the whistleblower. Many СКАЧАТЬ