Amex card numbers -- frustrating, and maybe insecure

Old Aug 18, 16, 10:14 am
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Amex card numbers -- frustrating, and maybe insecure

I have two Amex cards ending in 1007. I wouldn't be surprised if half of Flyertalk had at least one.

For a recent Hertz rental I wanted to make sure I got the Open savings, so I checked which card was the default in my Hertz profile. It said "1007." Not helpful -- I had to go in and check the whole number.

Then I got a pending charge from American Traffic Solutions -- the dreaded PlatePass fiasco I'll have to clear up (if it ultimately posts), since I used my own transponder.

I didn't know which Hertz rental it was from, so I went to the PlatePass site and did a search by card number. It asked for the first six and last four digits. Up came a receipt with the name and address of some other guy who happens to have a card with those same digits.

I guess Amex has used its numbering system for years, but it would be nice if they randomized the numbers a bit.

Seth
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Old Aug 18, 16, 10:17 am
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Those last numbers are the same for a reason just like the first 4 numbers. You can find a thread on the meaning if you are curious. Call Amex tell them your card was lost or stolen and you want a new card sent overnight. The last 4 digits will change. Problem solved.
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Old Aug 18, 16, 10:19 am
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Get a duplicate card. My original card was 1008, AU card was 1016, and the dup card I had to get was 1024. Each subsequent card increased by 8, it seems.
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Old Aug 18, 16, 10:19 am
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Related discussion here:

http://www.flyertalk.com/forum/ameri...rong-card.html
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Old Aug 18, 16, 11:00 am
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Thanks for the suggestions and link!

Seth
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Old Aug 18, 16, 12:37 pm
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Originally Posted by Centurion View Post
Those last numbers are the same for a reason just like the first 4 numbers.
Yes, but it is not a good reason and ought to be changed.
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Old Aug 18, 16, 2:58 pm
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Originally Posted by Markonen View Post
Yes, but it is not a good reason and ought to be changed.
Agreed. It's scary that I can feed 10 digits of my Amex into the PlatePass site, pull up the name of someone else who has the same kind of card, and know his address and the fact that he drove through a certain state on a certain date. That's more a fault of the PlatePass site, but Amex's predictable numbering doesn't help. If I stretched the search to before August I'd probably have had even more results.

Seth
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Old Aug 19, 16, 2:18 am
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Originally Posted by Finkface View Post
Each subsequent card increased by 8, it seems.
I think the increase is 1, i.e. consecutive. The last digit is a check digit AIUI. See bolded digits.
My original card was 1008, AU card was 1016, and the dup card I had to get was 1024.
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Old Aug 19, 16, 7:51 am
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I cancelled a card as stolen/lost ending with 1007. They re-issued me one with 2005 ending. However any purchases on ebay or amazon gets accidentally charged to 1007 as thats my default on the profiles. And AMEX let it through as valid charge....I have since replaced 1007 with 2005 card on my profiles..But how in the hell is AMEX letting charges go thru on my lost / stolen card? Very frustrating.
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Old Aug 19, 16, 10:15 am
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Originally Posted by MNSWEEps View Post
how in the hell is AMEX letting charges go thru on my lost / stolen card? Very frustrating.
I don't know the rules, but I don't think that should happen -- the whole point of reporting the card is to make sure that number can't be used. It shouldn't matter whether an attempt is made on the physical card or merely with the card number. The only exception would be items that were pending or pre-authorized before the card was reported lost or stolen.

Seth
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Old Mar 25, 17, 11:52 am
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I had 4 AmEx cards with the same last 4 digits (two with the same last 5). Called AmEx yesterday and requested new cards with unique last 4 digits to better manage the cards with online merchants. Rep said no problem and overnighted them. I was very explicit the I really wanted unique last 4 digits on each card and rep said he would ensure that was the case. Cards arrived today, all with the same last 4 numbers (and again, two with the same last 5). Very frustrating.
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Old Mar 25, 17, 3:18 pm
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Originally Posted by bodiddely View Post
I had 4 AmEx cards with the same last 4 digits (two with the same last 5). Called AmEx yesterday and requested new cards with unique last 4 digits to better manage the cards with online merchants. Rep said no problem and overnighted them. I was very explicit the I really wanted unique last 4 digits on each card and rep said he would ensure that was the case. Cards arrived today, all with the same last 4 numbers (and again, two with the same last 5). Very frustrating.
Why not just report the cards stolen once at a time to ensure the cards will have different last 4/5 numbers?
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Old Mar 25, 17, 3:44 pm
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This problem is built into the way that American Express generates card numbers. Replacing all the cards will result in parallel changes to all of them. This thread from 2003 may be of interest:

http://www.flyertalk.com/forum/ameri...rd-number.html
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