Entries Tagged "Nigeria"

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Far-Fetched Scams Separate the Gullible from Everyone Else

Interesting conclusion by Cormac Herley, in this paper: “Why Do Nigerian Scammers Say They are From Nigeria?

Abstract: False positives cause many promising detection technologies to be unworkable in practice. Attackers, we show, face this problem too. In deciding who to attack true positives are targets successfully attacked, while false positives are those that are attacked but yield nothing. This allows us to view the attacker’s problem as a binary classification. The most profitable strategy requires accurately distinguishing viable from non-viable users, and balancing the relative costs of true and false positives. We show that as victim density decreases the fraction of viable users than can be profitably attacked drops dramatically. For example, a 10x reduction in density can produce a 1000x reduction in the number of victims found. At very low victim densities the attacker faces a seemingly intractable Catch-22: unless he can distinguish viable from non-viable users with great accuracy the attacker cannot find enough victims to be profitable. However, only by finding large numbers of victims can he learn how to accurately distinguish the two.

Finally, this approach suggests an answer to the question in the title. Far-fetched tales of West African riches strike most as comical. Our analysis suggests that is an advantage to the attacker, not a disadvantage. Since his attack has a low density of victims the Nigerian scammer has an over-riding need to reduce false positives. By sending an email that repels all but the most gullible the scammer gets the most promising marks to self-select, and tilts the true to false positive ratio in his favor.

Posted on June 21, 2012 at 1:03 PMView Comments

Interview with a Nigerian Internet Scammer

Really interesting reading.

Scam-Detective: How did you find victims for your scams?

John: First you need to understand how the gangs work. At the bottom are the “foot soldiers”, kids who spend all of their time online to find email addresses and send out the first emails to get people interested. When they receive a reply, the victim is passed up the chain, to someone who has better English to get copies of ID from them like copies of their passport and driving licenses and build up trust. Then when they are ready to ask for money, they are passed further up again to someone who will pretend to be a barrister or shipping agent who will tell the victim that they need to pay charges or even a bribe to get the big cash amount out of the country. When they pay up, the gang master will collect the money from the Western Union office, using fake ID that they have taken from other scam victims.

[…]

Scam-Detective: Ok, I also want to talk more about how you managed to get your victims to trust you. I know it can be difficult for legitimate businesses to persuade customers to buy their products, yet you were able to convince people to part with their cash to get their hands on money that never existed in the first place, with at least one taking an international flight on top. That’s quite a skill, how did you learn to do it?

John: Once I had spent some time as a “foot soldier” (* sending out initial approaches and passing serious victims to other scammers) I was promoted to act as either a barrister, shipping agent or bank official. In the early days I had a supervisor who would read my emails and suggest responses, then I was left to do it myself. I had lots of different documents that I would use to convince the victim that I was genuine, including photographs of an official looking man in an office, fake ID and storage manifests, bank statements showing the money, whatever would best convince the victim that I, and the money, was real. I think the English term is to “worm my way” into their trust, taking it slowly and carefully so I didn’t scare them away by asking for too much money too soon.

Scam-Detective: What would you do if a victim had sent money and couldn’t afford to send more, or got cold feet?

John: I would use whatever tactics were needed to get more money. I would send faked letters which stated that the money was about to be taken out of the account by the bank or seized by the government to make them think it was urgent, or tell them that this was definitely the last obstacle to the money being released. I would encourage them to take out loans or borrow money from friends to make the last payment, but tell them that it was important that they didn’t tell anyone what the money was for. I promised them that the expenses would be paid back on top of their share of the money.

[…]

John: We had something called the recovery approach. A few months after the original scam, we would approach the victim again, this time pretending to be from the FBI, or the Nigerian Authorities. The email would tell the victim that we had caught a scammer and had found all of the details of the original scam, and that the money could be recovered. Of course there would be fees involved as well. Victims would often pay up again to try and get their money back.

This sounds just like any other confidence game; in fact, it’s a modern variation on a classic con game called the Spanish Prisoner. The only difference is that this one uses the Internet.

Posted on February 11, 2010 at 7:19 AMView Comments

New Real Estate Scam

Clever:

Nigerian scammers find homes listed for sale on these public search sites, copy the pictures and listings verbatim, and then post the information onto Craigslist under available housing rentals, without the consent or knowledge of Craigslist, who has been notified.

After the posting is listed, unsuspecting individuals contact the poster, who is Nigerian, for more information on the “rental.” The Nigerian scammer will state that they had to leave the country very quickly to do missionary or contract work in Africa and were unable to rent their house before leaving, therefore they have to take care of this remotely. The “homeowner” sends the prospective renter an application and tells them to send them first and last month’s rent to the Nigerian scammer via Western Union. The prospective renter is further told If they “qualify,” they will send them the keys for their house. Once the money is wired to the scammer, they show up at the house, see the home is actually for sale, are unable to access the property, and their money is gone.

Posted on July 29, 2009 at 5:31 AMView Comments

Who Falls for those Nigerian 419 Scams Anyway?

This is the story of a woman who sent the scammers $400K:

She wiped out her husband’s retirement account, mortgaged the house and took a lien out on the family car. Both were already paid for.

For more than two years, Spears sent tens and hundreds of thousands of dollars. Everyone she knew, including law enforcement officials, her family and bank officials, told her to stop, that it was all a scam. She persisted.

Spears said she kept sending money because the scammers kept telling her that the next payment would be the last one, that the big money was inbound. Spears said she became obsessed with getting paid.

An undercover investigator who worked on the case said greed helped blind Spears to the reality of the situation, which he called the worst example of the scam he’s ever seen.

EDITED TO ADD (12/13): More about the story.

Posted on December 3, 2008 at 8:20 AMView Comments

Top 10 Internet Crimes of 2006

According to the Internet Crime Complaint Center and reported in U.S. News and World Report, auction fraud and non-delivery of items purchased are far and away the most common Internet crimes. Identity theft is way down near the bottom.

Although the number of complaints last year­207,492­fell by 10 percent, the overall losses hit a record $198 million. By far the most reported crime: Internet auction fraud, garnering 45 percent of all complaints. Also big was nondelivery of merchandise or payment, which notched second at 19 percent. The biggest money losers: those omnipresent Nigerian scam letters, which fleeced victims on average of $5,100 ­followed by check fraud at $3,744 and investment fraud at $2,694.

[…]

The feds caution that these figures don’t represent a scientific sample of just how much Net crime is out there. They note, for example, that the high number of auction fraud complaints is due, in part, to eBay and other big E-commerce outfits offering customers direct links to the IC3 website. And it’s tough to measure what may be the Web’s biggest scourge, child porn, simply by complaints. Still, the survey is a useful snapshot, even if it tells us what we already know: that the Internet, like the rest of life, is full of bad guys. Caveat emptor.

Posted on April 24, 2007 at 12:25 PMView Comments

Sidebar photo of Bruce Schneier by Joe MacInnis.