Paypal follow-up

Some people wonder whether the situation with PayPal is that bad.  Well, at least the phishing part is.  Today’s mail included this little gem from points unknown pretending to be PayPal:

Attention! Your PayPal account has been limited!


[Link to a phishing site]

This is the Last reminder to log in to PayPal as soon as possible. Once you log in, you will be provided with steps to restore your account access.


How did I know this was a forgery?  Let’s take a look at the email headers:

Return-Path: <>
Received: from ( [])
	by with ESMTP id n9GAJ9h3022332
	for <>; Fri, 16 Oct 2009 12:19:31 +0200
Received: from ([]) by with Microsoft SMTPSVC(5.0.2195.6713);
	 Fri, 16 Oct 2009 06:32:45 -0400
From: "PayPal Services" <>
To: "lear" <>
Subject: Your PayPal account has been Limited
Date: Fri, 16 Oct 2009 10:18:53 +0000
Organization: PayPal
MIME-Version: 1.0
Content-Type: multipart/alternative;
Message-ID: <>
X-OriginalArrivalTime: 16 Oct 2009 10:32:45.0859 (UTC) FILETIME=[00099730:01CA4E4C]

The first thing we note is the From: line.  While this line can be easily forged, in this case, the miscreant forged not paypal’s domain but‘s.  Well, that’s not PayPal.  This one was easy to establish as a fraud.  But had we any doubts we would need look no further than the previous two lines (the last Received: header).  If we look at the address, which is claimed to be, we note that the name it has begins with “dynamic”.  That name, and the numbers that follow in it, indicate that this is probably someone’s house or office PC, and not paypal’s email server.  Note I’ve highlighted to “To” line, with the address  But that is not the address I’ve given PayPal.

What’s more, I happen to have an actual set of headers to compare against.  Here is what it looks like:

Return-Path: <>
Received: from ( [])
	by (8.14.3/8.14.3/Debian-6) with ESMTP id n9E8KIwI026171
	for <>; Wed, 14 Oct 2009 10:20:39 +0200
Authentication-Results:; dkim=pass
	(1024-bit key; insecure key);
	dkim-adsp=none (insecure policy)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;;; q=dns/txt; s=dkim;
  t=1255508439; x=1287044439;
Received: (qmail 22290 invoked by uid 99); 14 Oct 2009 08:20:17 -0000
Date: Wed, 14 Oct 2009 01:20:17 -0700
Message-Id: <>
Subject: Receipt for Your Payment to XXXX
X-MaxCode-Template: email-receipt-xclick-payment
To: Eliot Lear <>
From: "" <>
X-Email-Type-Id: PP120
X-XPT-XSL-Name: email_pimp/CH/en_US/xclick/ReceiptXClickPayment.xsl
Content-Type: multipart/alternative;
MIME-Version: 1.0

A few things to note: first, there my own mailer adds an Authentication-Results header, and in this case you see dkim=pass.  It’s done that by looking at the DKIM-Signature header to determine if Paypal really did send the email.  This is a strong authoritative check.  Knowing that PayPal does this makes me feel comfortable to discard just about any email from that lacks this header.  Also, this email was addressed to the correct address (I’m not actually showing the address that I use).  Not every site uses dkim and that’s a pity.  One has to know in advance when to expect dkim=pass and one has to look at the headers to check.

Just by comparing email headers we can see that this is a poor forgery.  And yet it takes time and effort for people to determine just that.  And this is the risk that we consumers face.  If one decides that any email one wasn’t expecting from PayPal is in fact a forgery, then should someone break into one’s account, one may not notice that there is a problem.

Summarizing, here are the things that I’ve done to limit the chances of something bad happening:

  1. I use a single email address for PayPal that forgers are unlikely to know about.
  2. I look for the Authentication-Results header.
  3. Even if I think this is an authentic email, I will not click on links, but instead go to

But it’s not all that easy for me.  It certainly isn’t easy for those who haven’t been paying attention to all of this stuff as part of their job.

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A lesson in transitive trust

CybercrimeGrowing up in the New York area in the 1970s, one never really paid attention to all the crime that occurred.  There just was so much of it.  Even when I lived in California, while a murder would make the local news, it wasn’t something that would shake the community.  A murder in the Zürich area, however, is rare.  Maybe it’s because everyone has a gun, as my friend Neal might say.  Who knows?  The point is that people here are not inured to that level of violence.

Now we are discovering the online version of that.  When last we left our situation, we were trying to figure out how best to protect ourselves from evil bad guys by limiting the damage dumb passwords can do.  Since then, it has been widely reported that 10,000 Hotmail account passwords were stolen.  But they weren’t the only ones.  Many of the people who use Hotmail accounts also have GMail and Yahoo! accounts, and many of those passwords are the same.  Why?  Because humans don’t like having to remember lots and lots of passwords.  And of course, if you were one of those people who used the same password between both and linked your Yahoo or GMail account to Facebook, that means that your Facebook account could have been compromised as well.  And that means that your friends may have been attacked, as we previously discussed.

How could this be worse?  Let’s add Paypal into the mix.  If you use the same password for eBay as you used for Yahoo!, now all of a sudden, you have invited someone to empty your bank account.  Had Paypal implemented an OpenID consumer for login, an attacker wouldn’t even need your password.

Now let’s aggregate all of the people who do that.  The popular OpenID providers include Google, Yahoo, and Verisign.  As the number of providers increases, the concentration of risk of any one single failure decreases.  Concentration of risk is a fancy way of saying that one is putting all of one’s egg in one basket.  On the other hand, from the perspective of a web site that uses OpenID or some other federated mechanism such as SAML, the information received from any random Identity Provider (IdP) could reasonably be considered suspect.

This leads to a few conclusions:

  • A large number of Identity Providers will require a service that provides some indication as to the reliability of the information returned by a given IdP.
  • The insurance and credit industries can’t manage concentrated risk.  We’ve seen what happens in the housing market.  The Internet can reproduce those conditions.  Hence, there will be limitations on transitive trust imposed.

Conveniently, you are not without any protection, nor are the banks.  There are large federated market places already out there.  Perhaps the two biggest are eBay and Amazon.  Amazon has the advantage of requiring a physical address to deliver to, for most goods, the exceptions being software, soft-copy books and downloadable movies.  In each of these cases, the transaction value tends to be fairly low, and the resale value of most of these items is 0.  It’s the resale value that’s important, because the miscreants in this business don’t want 150 copies of Quicken for themselves, nor can they really sell off an episode of House.

Paypal is another matter.  If someone has broken into your Paypal account, here is what they can do:

  • Empty it of any credit it might have;
  • Charge against your credit cards; and/or
  • Take money from your bank.

If you’re paying attention and act quickly, you might prevent some of these nasties from happening.  But first you will have to read a tome that is their agreement.  In all likelihood you have no recourse to whatever final decision they make.  If you’re not paying attention, your account and those associated with it become an excellent opportunity for money laundering.  What does it mean to pay attention?  It means that you are receiving and reading email from  That means that they have to have a current email address.  When was the last time you checked that they do?  Assuming that they do, it also means that you have to read what you are receiving.  Now- I don’t know about you, but I’ve been spammed to death by people claiming to be PayPal.  Remember, how this posted started by talking about being inured to crime?  Well, here we go again.

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Can The Industry Stop break-ins on Facebook?

FacebookAfter my last post, a reasonable question is whether we in the industry have been goofing off on the job.  After all, how could it be that someone got their account broken into?  Everyone knows that passwords are a weak form of authentication.  Most enterprises won’t allow it for employee access, and we would string a bank CSO up by his or her toenails if a bank only used passwords to access your information. They use at a bear minimum RSA one time password tokens or perhaps Smart Cards.  So why are the rules different for Facebook?

They would say, I’m sure, that they do not hold the keys to your financial data.  Only that may not be true.  Have you entered credit card details into Facebook?  Then in that case maybe they do hold the keys to your financial data.  Even if you haven’t entered any financial data into Facebook?  Are you using the same password for Facebook that you are for your financial institution?  Many people are, and that is the problem.

Passwords have become, for want of a better term, an attractive nuisance.  It’s not that the concept itself is terrible, but they are increasingly difficult to secure, as the number of accounts that people hold continues to skyrocket.  Yes, the problem is getting worse, not better.  My favorite example is the latest update to the Wall Street Journal iPhone app, where the upgrade description says, “Application Enhancements to Add Free Registration & the Ability for Subscribers and Users to Login”.  What a lovely enhancement.  Right up there with enhancing the keyboard I am typing on to give me electric shocks.

Facebook is at least making a feeble attempt to get around this problem by offering OpenID access in some limited way (I tried using it from this site, and FB is broken, even though I can get into all sorts of other sites, including LiveJournal).  Still, it probably works for you if you are a Google, Yahoo!, or MySpace user, but for better or worse those sites themselves do not accept OpenID.  (The better part is that no one can simply break into one account and gain access to all of these other sites.  The worse part is that if you have some other OpenID, you can’t use it with these sites.)

OpenID has lots of problems, the biggest of which is that there is no standard privileged interface to the user.  This is something that Google, Yahoo!, and MySpace might actually like, because it means that they provide the interface they want to provide.  Unfortunately, programs, or more precisely the authors of programs, might find that a little irritating, since OpenID is so closely tied to the web that it is difficult to use for other applications (like email).

SAML and Higgins to the rescue?  OAUTH?  Blech.

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Beware Facebook Scams! Protect yourself!

CybercrimeAs Facebook now has more accounts than there are people in the United States, it should come as no surprise that it is possible to break into some of those 300 accounts.  This happens.  Well, what happens next when an attacker breaks into a Facebook account?  Several things are likely.  First, the attacker will retrieve as much information about the individual and his or her friends as possible.  There are several key pieces of information that prove valuable:

  • Birthday and Hometown are enough information for an attacker to reliably predict social security numbers of people born after 1989.  You can hide this information from your profile by going to your profile, clicking on the little box in the upper right of the Information tab, and deselecting birthday and home town.
  • Email address is useful to feed into a phishing/spam engine.
  • Telephone # and IM account information is enough to either use or sell to other scammers.

Next, an attacker may try to directly contact friends to scam money out of them.  While such attacks are unlikely to take the form of a 419 scam where the attacker tries to play on greed, they will more likely play on peoples’ sympathies.

Here is an example:

0Wn3d Friend: Hey
0Wn3d Friend: How are you doin?
Target: good evening, Friend!
Target: i’m doing well, and you and your family?!
0Wn3d Friend: Not too good
Target: oh?
0Wn3d Friend: We are in a very deep mess
0Wn3d Friend: Glad you are here
Target: what happened?
0Wn3d Friend: We are stranded in London England
Target: WHAT?!  how so?
Target: where?
Target: (in london)?
0Wn3d Friend: Kentish Town
0Wn3d Friend: We got mugged on our way back to the hotel at a gun point
Target: oh geez
Target: have you gone to the police?
Target: do you have a phone?
0Wn3d Friend: Yes,We were able to file a report to the cops and that is been Investigated
0Wn3d Friend: They made way with all we got here
0Wn3d Friend: Cash,bank cards and also the cell phone
Target: ok.
Target: i have a few friends outside of london.  are you in a hotel?
0Wn3d Friend: Yes
Target: do you still have your passports?
0Wn3d Friend: Yes,I’m still safe with the Passport
Target: ok.  how long are you supposed to be in London?
0Wn3d Friend: That has been the problem
0Wn3d Friend: I seriously need your urgent help getting back home
Target: what hotel are you in?
0Wn3d Friend: Sector Hotel
0Wn3d Friend: I have a flight back home in the next 3hrs but the hotel management won’t let go
Target: do you have the hotel’s address & phone #?
0Wn3d Friend: I don,t have the #
Target: i’ll need an address
0Wn3d Friend: 151 Kentish Town Road, London, NW5 2CG
0Wn3d Friend: I’m having problem with the hotel on the bills

What happens next is that the attacker asks for a credit card.

So how do you know it’s a scam?  First, Amazingly, Google is your friend.  If you enter just a few details from this example, you’ll see that Kentish Town and the Sector Hotel show up as a scam. The other odd thing about this exchange is that the person claims to have been mugged at gun point in London.  I’m not saying it doesn’t happen, but it’s rare.

More importantly, ask yourself why this friend is contact you, and not calling a relative for help.  To be sure, if this person really is a friend, you should already have a phone number for that person.  Call him or her, but do not rely on contact information from the attacker.  Calling a number they give you can cause you to lose a lot of money.  If they answer the phone and have no idea what you’re talking about, you know it’s a scam.  If they don’t answer, call a relative of theirs or ask for more details.  In this case the person said they filed a police report.  Get the report number from the person, name of an officer who took the report, and independently call the police.    Do not rely on anything in the facebook profile of the friend.  You should assume the attacker has already manipulated all of that information.

Most importantly, never send credit card information over the network in such circumstances.

Ok, so you’ve figured out it’s a scam.  Congratulations!  What do you do next?  Report it, and fast.  Facebook is pretty responsive when it comes to shutting down accounts.  In one case I’ve reported, they reacted within 10 minutes.  To report abuse on facebook, click on Help at the bottom of the page, and right at the top you will find the following:

Hacked accounts and spam

Click on that text, and it will help you report the information.  You will need the URL of the profile of the friend who you are reporting.  To get this, type the friend’s name in the search bar.

Don’t feel bad that you are reporting a friend, either.  This is a case where your friend is being maliciously used, and you are doing your part to putting an end to it.

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New Research: Social Security Numbers (SSN) are Entirely Predictable

CybercrimeNew research published in yesterday’s Proceedings of the National Acadamy of Sciences has dramatic implications for Americans and identity theft.  Alessandro Acquisti is an Associate Professor of Information Technology and Public Policy at Heinz College of Carnegie Mellon.  He has spent the better part of two years with his colleague Ralph Gross, looking at social security numbers as both identifier and authenticator, something we have all known was a bad combination.  Professor Acquisti demonstrates just how bad of an idea it has been in the last twenty years.  In that time there have been two significant policy changes that have made numbers extremely predictable based on two pieces of information:

  • birth city
  • date of birth

The policy changes involve release of something known as the Death Master File (DMF), which was intended to prevent someone from expropriating a dead person’s identity, and the Enumeration at Birth (EAB) initiative, which has had the effect of allocating SSNs shortly after birth.  These combined with the facts that SSNs have structure based on location, and that the less significant components are serialized in allocation, and it makes for a predictable SSN.

This gets worse.  While it may be possible to fix this problem for future generations that use SSNs, either by randomizing all or lesser components, or by not filing applications upon birth, the millions of people who have assignments in this time period are in an extremely difficult spot, because the workaround is a change of number.  This argues for a new form of identity that separates authentication and identity, but the effort to do so requires that the finance, education, and medical sectors (not to mention government)  change their means of identifying individuals.  This will be no easy task.

This research is a remarkable piece of work by Professor Acquisti and his colleagues.

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