The gift of the gab: Are rental scammers skilled at the art of persuasion? Sophie Van Der Zee, Richard Clayton, Ross Anderson Computer Laboratory, University of Cambridge, JJ Thomson Ave, Cambridge, CB3 0FD, UK, [email protected] [email protected] [email protected] November 20, 2019 Abstract Rental scams are a type of advance fee fraud, in which the scammer tries to get a victim to pay a deposit to rent an apartment of which the scammer pretends to be the landlord. We specifically focused on fraudulent long-term rentals advertised in the UK on Craigslist. After a victim responds to the scammer’s advertisement, the scammer attempts to persuade them to transfer money without having seen the property. We were interested in which persuasion techniques scammers use, and in assessing their skill at the art of persuasion. During a period of three weeks, we scraped 2 112 letting advertisements, identified the fraudulent advertisements and had 44 conversations of around 4 or 5 emails each with the scammers. Our analysis indicates that Cialdini’s marketing-based social persuasion strategies, such arXiv:1911.08253v1 [cs.CY] 19 Nov 2019 as liking, appeal to authority, and the need for commitment and consistency are extensively implemented by rental scammers. Of Stajano and Wilson’s scam-based persuasion strategies, an appeal to sympathy (i.e., kindness) and need for greed were commonly used. We identified two further social persuasion strategies: establishing credibility and removing objections. At a superficial level, rental scammers seem skilled at their job, because they mimic genuine landlords and use a range of effective persuasion techniques. However, when examining their emails more closely, we see they often use pre-scripted emails, their mimicry is often incompetent, and they have a lack of language skills and cultural knowledge that may tip people off. They appear to be the criminal equivalent of a boilerhouse sales operation, a modus operandi that has not previously been studied by cybercrime researchers. 1 1 Introduction Fraud, the act of deception for personal gain, and its deterrence, can be traced back to ancient times. It is a recurring theme in Greek mythology, with many stories about Dolos (the spirit of trickery and guile) and Apate (the goddess of fraud and deceit). Although fraud has occurred throughout history, its prevalence and shape have changed over time. Technological developments such as the post, telephone and fax enabled fraudsters to target potential victims more efficiently, removing the need for face-to-face contact [33]. The latest evolution started in the nineties when the use of email became widespread [2, 16]; as more and more people went online, scammers started to use the Internet to target millions of people worldwide while concealing their true identity and location [9]. Although the Internet has affected a range of existing fraud types and created several new ones, it has greatly increased the ease and incidence of advance fee frauds (AFF). Also called ‘419 scams’ from the relevant article in the Nigerian Criminal Code, these typically involve tricking a potential victim into transferring money by persuading them that they will shortly receive a larger sum of money in return [5]. Scammers experiment with different story-scripts [33], but a classic tactic is to im- personate a wealthy and powerful person with access to a large sum of money [9]. The scammer’s tale is that before this fortune can be accessed, he needs an accomplice; then a small payment needs to be made, for example to cover processing fees, unforeseen taxes or insurance. The collection of these ‘advance fees’ is the real objective of the scam [21]. AFF in its current international form, originated in Nigeria in the seventies and is still largely driven by fraudsters from West Africa [5, 21]. A sense of historical revenge provides a sense of justification to at least some scammers; during the trial of Nigerian lawyer and alleged fraud kingpin Fred Ajudua, for a series of 419 offences, he claimed that the frauds were “compensation from white men for slavery and colonialism” [12, 23]. 1.1 Rental scams A specific type of AFF is the rental scam. We came across different types of rental scams, including short-term holiday rentals and long-term letting. On the long-term rental market, scams can be divided between those where an apartment can be viewed before payment is made, and scams in which viewing is not possible [27]. In the latter, the victim responds to an advert for a property and pays money up front without viewing the place. The scammer’s advertisement may make the property seem especially desirable or the rent may be set below the market rate. Once a potential victim answers, emails are exchanged and then a reason is found for the victim to transfer money. Although not being able to view a property before renting would serve as a red flag for some people, it may not put off students and other people who move across country or 2 even across borders, as they may have no choice but to rent sight unseen. In other cases, the scammer is prepared to offer a viewing but only once a fee has been paid to cover a credit check, postage for sending keys for a viewing, or a deposit may be requested along with advance rent. In some cases the victim may just be asked to make a Western Union payment to a friend to show that they have sufficient funds, but the scammer impersonates the friend and steals the money. Although rental scams have not previously been studied in the literature, they are widespread. Based on an online survey by Shelter in 2010, the UK National Fraud Authority estimated that all rental scams together annually cause 315,000 victims to lose on average of £2,394, leading to an overall cost of £755 million a year [20]. However, the Shelter survey covered many other types of rental scams besides the AFF version that we discuss here [24] and in particular it included disputes where a landlord refuses to refund a tenant’s deposit. As an order of magnitude estimate for the AFF component of the overall fraud figure, we attempted to determine how many Cambridge students had been affected by such frauds in 2014. The police received 44 victim reports, but all appear to be for a specific scam that targeted students with fake websites, local phone numbers and some convincing paperwork. Scaling this up across all UK students (of which around 1% are in Cambridge) would imply an overall impact of around £4 million per annum, but this will be on the high side because the scam was specific to Cambridge and a handful of other towns, and was rather more convincingly executed than the scams that we look at in this paper. Equally not all victims are students and not all victims report their loss to the police – so our best estimate is that the annual take from AFF style rental scams in the UK is in the range £2–10 million – and may be of a similar magnitude in several other countries because we have also seen scams targeting rentals in other European and US cities. We personally got interested in rental scams when the first author encountered a fake letting advertisement when moving to Cambridge for a post-doctoral research position. Fortunately, she realised it was a scam before transferring money, but it made her re- alise how well-crafted this type of AFF could be. Since then, she has been in contact with several people at the University of Cambridge who have lost money this way. The experiences of four scam victims are described later in this paper. Other indications that rental scams are becoming a serious issue is provided by large housing websites such as Craigslist, Trulia, and Zillow, which now explicitly mention rental scams in their help section on “how to avoid getting scammed” [7, 28, 32]. Although many fraudsters appear to operate from outside the jurisdiction, in some cases criminals have been caught and prosecuted. 3 1.2 Why do scams work? To understand why scams succeed, and to prevent others from falling victim in the future, researchers have tried to determine why victims fall for scams. For example, Modic and Lea investigated how personality traits correlate with the likelihood of being scammed, and found that traits such as extraversion and openness can put one at risk [19]. Although an interesting result, it is not obvious how we might use it to reduce the number of incidents. An alternative approach involves studying the methodology of scams [31]. Previous research has demonstrated that scammers tend to borrow social persuasion strategies from the marketing industry [26, 6]. For example, interviews with real victims show that scammers frequently appeal to scarcity (highlighting a limited offer), authority (forging emails from the FBI) and exploit people’s greed (stressing the amounts of money in- volved). Carter’s text analysis of postal scams revealed that scammers appeal to scarcity, but also inspire secrecy [4]. Wilson experimented on unwitting members of the public using a variety of (staged) scams in the BBC TV program “The Real Hustle” [26]. Stajano and Wilson demonstrated that these scams implement all six social persuasion strategies identified by Cialdini: reci- procity, commitment and consistency, liking, authority, scarcity and social proof [6], plus the ‘need and greed’ principle described by Lea et al. [18]. Their analysis also identified three additional persuasion techniques: ‘distraction’, ‘dishonesty’ and ‘kindness’, leading to a total of ten scam-related persuasion techniques.