I am organising an upcoming conference and some of our participants were approached by Expo Housing Services, a company claiming - falsely - to be charged with arranging accommodation for our guests. The details of their operation, specifically targeting scientific conferences are explained here, in a warning on an Elsevier's bio-science event website (in short: under some pretense credit card details are requested, loss of funds ensues) which I was able to find quickly googling "EHS scam". However, to do that I needed to know the fraudster's name, which changes often.
Frankly I am amazed that scientific conferences are a big enough market for the scam to persist (google search returns hits from as far as 2014), but it concerns me that I have never heard of such a scam tailored towards academics. So suppose I would like to raise awareness of this scheme. How to communicate such scams to a wider academic community?
Obviously, I figured that writing on academia.stackexchange is a good first step (also, to the best of my search skills, this topic was not raised here yet). I can of course warn colleagues in my field, but EHS does not discriminate and targets various disciplines (and operates in various countries).
There is one more question here. What reasonable measures can I take to prevent scammers from reaching my participants? EHS called two invited speakers of my conference (obtaining their numbers from their institutions' websites, I presume), so I could simply not publish the invited speakers list. To clarify, this is a mathematics conference where we announce in advance several top-tier experts to be present and then expect members of community to register based on their interest in specific topics that these invited speakers are known to work on - you see why I don't consider anonymity a reasonable mesure. I am very curious if in any parts of academia there are protocols in place to prevent third parties from pretending to be associated with a conference. I'm considering adding appropriate disclaimers to websites of any future events I will organise, although I am aware that a significant portion of visitors only read participant lists.
I know that I am not responsible for the unsolicited contact from EHS (to be clear, there was no leak on my end - the scammers used only public information), but at the same time I can't shake the feeling that the very situation (or especially potential loss of money) reflects badly on me.
EDIT: 15.07.2018. Thank you all for the input. I am now after the conference and I figure an update of the story would not go amiss.
First of all, I accepted @KareemElashmawy answer, since I came to agree that it is on the relevant authority for the community to warn about and fight such scams: not on the particular organizer, and not on the particular university. I contacted my national maths society and they were very interested. I feel they will try to deal with the problem.
However, I also contacted several people at my faculty that I know were organizing conferences this summer. The mathematicians were grateful for the warning (not one mathematician whom I asked - and I did, home and abroad - ever encountered such scam), but the computer scientists dismissed me, because "they know the problem very well and it's no news to them". I was frankly astonished that this knowledge did not pass to me (or other mathematicians) from people working in the same building. Unfortunately I don't know any reasonable way to exchange such tacit knowledge between fields - to find one was a part of my motivation for asking this question here, but since no answer weighed in on this topic I guess I did a poor job of conveying that. Of course the issue of inter-fields communication is not easy (as witnessed in this case by my CS colleagues) and I greatly appreciate the comments from astronomers, chemists and statisticians that appeared here. It would be very interesting to understand why some groups were targeted by (and thus warn about) such scams, and why some were not (yet).
I also followed @Kareem's advice to contact the law enforcement, which wasn't my first instinct and here is why: I was only able to testify that maybe someone from an unspecified country tried to impersonate me (or just falsely presented themselves as an affiliate of my university, maybe) in order to maybe steal money from a third party, also maybe in a different country. I was utterly unsurprised that the policeman told me that since neither me or the university lost any money, short of the university claiming image losses we have no legal action. I left it at that, since I know my university would not have any interest in pursuing this route. There is of course also an issue of jurisdiction, since the chances the local law enforcement could reach the foreign scammers are pretty slim. I need however to stress that this paragraph is very country-, university-, or even perhaps the-policeman-talking-with-you-specific.
The links to Comic Con and Yankees 2016 that @Kareem has provided helped me to stop worrying too much about my participants - if a Comic Con attendee wants to buy the ticket from a shady source, it is on them if the ticket will turn out useless, and quite the same with my participants. Needless to say, the moment I heard about the attempt of this scam I did email all my participants, reiterating who are the only people that should be contacting them on our behalf (and with what - collecting abstracts is okay, asking for credit card details is not). It was too late to give any warning on the registration form (since by that time it was almost closed), but I will of course do that the next time I organize anything - and I will probably do it in @einpoklum's style:) However I now feel that such a warning is all that should be expected of the organizers in such situations.
Last but not least, I think that the conned participant got his money back, via Chargeback (I give a link, since I am illiterate at banking and did not know about it until this scam). It certainly didn't mar his stay, he seemed very happy to visit us despite the unfortunate start.
Again, thanks to everyone for sharing their thoughts.