K-Squared Ramblings

Flagging (Non)-Spoofed Mail

Following up on the PayPal anti-phishing discussion of a few weeks ago, I see that PayPal is promoting a service called Iconix. You install the program on your system, and it looks at your inbox for messages that claim to be from one of its customers. It tries to verify them “using industry-standard authentication technologies such as Sender ID and DomainKeys.” Messages that pass get a lock-and-checkbox icon attached to the sender’s name, and in some cases the name is replaced by the sender’s logo.

On the tech side, it’s similar to SpamAssassin’s whitelist_from_spf and whitelist_from_dkim features. Both allow you to specify a sender to whitelist, and it will only give a message special treatment if it can verify the sender.

On the user-interface side, it’s similar to EC certificates, in that it tries to highlight a “good” class of messages rather than flag or filter out a “bad” class.

It’s not a bad idea, actually, and now that I’m surprised I haven’t seen something similar in other email clients. It’s sort of like setting up custom rings or images for images on your cell phone address book

They seem to be focused on webmail and Outlook so far, and only on Windows, but it looks like the perfect candidate for a Thunderbird extension. They do have a sign-up form to notify you when they add support for various programs and OSes, and I was pleased to see not only Thunderbird and Mac OS listed, but Linux as well. Too often, Linux gets forgotten in the shuffle to ensure compatibility with every Windows variation.

Nasty Ebay “About Me” Phish

Someone I know encountered a really sneaky eBay phish this weekend. It arrived through eBay’s official “Ask seller a question” system, and consisted of a simple request: Was his auction the same as the auction at the following About Me page?

The URL was a normal eBay URL of the form http://members.ebay.com/aboutme/_____. Pasting the link into another browser brought up the user’s About Me page… which consisted of a spoofed eBay login form that would submit the username and password to a page hosted at Yahoo.

So it not only came through eBay’s official messaging system, but the form appeared on eBay’s own website, meaning it bypasses many of the usual cues. It’s not a secured page, but use of SSL for login pages is still spotty enough that a user could easily miss that. And how many people have noticed that eBay only puts login forms on signin.ebay.com? You have a slightly better chance if you have a browser like Opera, which shows you the target* of a form when you hover over a button. If you think to look at it. Read the rest of this entry »

Flash Fraud

Got an interesting phish today.

Subject: Error in your billing information
From: Keystone Savings Bank.

Hmm, Keystone, eh?

Back to Basics: Phish by Phone

I just spotted a rather disturbing phishing message in (of all places) our abuse contact mailbox:

Subject: Fraud Prevention Measures

Dear customer!

Due to high fraud activity we constantly increasing security level both for online banking and card transactions. In order to update our records you are required to call MBNA Card Service number at 1-800-[removed] and update information on your MBNA card.

This is free of charge and would not affect any transactions with your card. Please note this is necessary to provide highest security level for all transactions with your card.

No HTML tricks. No links to fraudulent websites. Just a phone number.

I can only assume this is a response to high-profile inclusion of antiphishing features in Internet Explorer 7 and in Firefox 2. If there’s no website, there’s nothing for a web browser to check.

And of course by not using sneaky technical tricks in the message, it’s harder for tools like ClamAV, spam filters, or mail clients to detect.

Incidentally, does anyone else find it ironic that one of the most common phishing techniques is to exploit people’s fear of being phished?

Further reading: Anti-Phishing Working Group.

Thank you, Captain Obvious

OK, I appreciate that eBay has a dedicated email address for reporting phishing attempts. I appreciate that their abuse department is a lot busier than I am, and therefore has to rely heavily on form letters. And I appreciate that they’re making an effort to educate the public on how to spot phishing and avoid getting caught.

But when I forward them a message with the comment, “Here’s a sample of a blatant phish,” is it really necessary to reply with the full two-page notice explaining, “This is a spoof, we didn’t send it, here’s how to avoid it, blah blah blah” and the entire body of the original message, complete with the links to the phishing site?

I’d think in this case a simple, “Thanks for the report, we’ve notified the authorities” note would be sufficient, especially since the “how to spot a phish” stuff is already in the auto-response. All it takes is giving their abuse staff an extra choice for the form letter.

And under no circumstances should they be including the full, original text of the phish. At best, it’s asking for the response to get lost in a spam box or blocked outright. At worst, it’s a security risk waiting to happen (since this copy really did come from eBay). Somewhere in the middle is the risk of mucking up adaptive filters as they try to reconcile the original message, which was spam, with the new message, which isn’t.

Spam is like machine gun fire

After my latest round of supposed anti-fraud notices claiming to be from banks with which I don’t have any accounts, it occurred to me that phishing, 419 scams, email spam, blog spam, etc. are all scattershot approaches. They seem so obvious to those of us who are used to seeing them. It seems unthinkable that someone would fall for a phishing attempt that identifies itself as someone else’s bank, or buy pharmaceuticals from someone who can’t spell d.Ruugz. But they’re not intended for us. We’re just collateral damage.

Direct marketing often makes at least an effort to aim, because paper and postage cost money. That’s why businesses and charities will mainly share/sell their mailing lists among similar organizations, and not some random list of people. In this way, direct marketing is like riflery: you want each shot to be as accurate as possible.

Email, however, is cheap, and most spammers are using someone else’s resources to send out the mail anyway. It’s long been pointed out that they don’t care if 99% of their messages get lost in the ether. They only need a fraction of their list to respond. It’s like using a machine gun: you don’t have to aim, just spray the general area and at least one bullet is likely to hit your target.

So phishers don’t have to match their pitches to each recipient’s bank. If they plaster the net with messages claiming to be from Chase, it doesn’t matter if most of their messages hit Wells Fargo customers. Statistically speaking, some of the recipients will have Chase accounts, and some of them will be fooled, and that’s all they need to collect their virtual loot.

And the rest of us? Bystanders caught in the drive-by.

Symantec Issues

Last week I received a message offering a 30% discount on Norton Internet Security 2006. It claimed to be from Symantec, but the email address was at digitalriver.com, and all the links—including the ones that claimed to be at symantec.com—went to bluehornet.com.

Now 5 minutes of research turns up the facts that Symantec does work with Digital River and Digital River owns Blue Hornet. And it did go to the address I used to register Norton Antivirus last year. So it’s probably a legit offer.

But let’s think about this for a minute.

Assuming it’s legit, Symantec—a company that deals in internet security—is deliberately sending out offers via third-party domains, email and web servers. Depending on how security-conscious you are, they are either making their messages look suspicious or training users to ignore warning signs.

Or have you never seen spam offering enormous discounts on Norton products? Which generally turn out to be pirated. And I seem to recall—though I can’t find an article to back it up—that the bootleg copies are often infected themselves, or crippled in some way.

Given how many shady operators are out there, taking advantage of the big guys’ name recognition, you’d think the big guys would at least make some effort to make their own offerings look less, well, shady.

Low-Tech Phish

I found a flood of crude phishing attempts in our postmaster account this morning.

How crude?

The hook was, “Simply reply to this email with your online login and password.”

No forms, no imitation websites, no swiped logos, no links of any sort at all. One of them even had multiple recipients visible on the To: line. It’s like a throwback to the early days of spam-n-scam.

The headers were full of things like %RNDDIGIT27, suggesting a broken spam generator, and of course there’s the fact that they actually targeted the postmaster account.

How Thunderbird’s Scam Detection Works

Since upgrading to Mozilla Thunderbird 1.5 beta 2, I’ve seen a number of messages slapped with a warning label that “Thunderbird thinks this message might be an email scam.” It appears at the top of the message, in the same style as the junk mail notice bar or the warning that remote images have been blocked, and there’s a button to mark the message as “Not a Scam.”

There’s only one problem. Since SpamAssassin and ClamAV do such a good job of catching the phishing scams before they reach my inbox, Thunderbird has yet to catch any actual phish. But there’ve been a lot of false positives. It’s hit LiveJournal reply notices, newsletters from IEEE and Golden Key, a Spam Karma notice from my own blog, and I’ve seen it on both outbid notices and updates to saved searches from eBay.

I found myself wondering just how Thunderbird’s phishing detection decides that a message is suspicious—and how to teach it that the next LJ notice isn’t a scam.

The Thunderbird support website doesn’t seem to have been updated yet. Most of the articles I’ve found only talk about TB adding the feature, not how it works. The best information I found was this Mozillazine forum thread, which included a link to the actual code that makes the decision, in phishingDetector.js. Thunderbird looks at the following:

• Links that only use an IP address, including dotted decimal, octal, hex, dword, or some mixed encoding.
• Links that claim to go to one site, but actually go to another. (Phishers do this to fool you into going to their site. Legit mailing lists sometimes do this with redirectors for tracking purposes.)
• Forms embedded in the email. (This explains the LiveJournal notices.)

It also appears to trap text URLs containing HTML-escaped characters, which explains the Spam Karma reports. In this case the report includes a spammer’s link with ​ in the hostname. The message is plain text, so Thunderbird leaves the entity as-is when displaying it…but decodes it when it creates the link. Result: a link where the text and URL don’t match.

The easiest way to prevent it from freaking out over the next message? Add the sender to your address book. I’m not sure that’s a great idea, since a phisher could guess which addresses you have saved and spoof them, but it’s at least simple. I guess I’ll find out whether it works the next time I get a reply notice from LJ. Update: Adding the sender to your address book doesn’t seem to have any effect.

Update 2 (July 12, 2006): The comment thread’s gotten long enough that I can see people might miss this, so here’s how to disable it:

1. Open Options or Preferences (this will be under the Tools menu on Windows, Thunderbird on Mac, or Edit on Linux).
2. Click on Privacy (there should be a big padlock icon).
3. Click on the E-mail Scams tab.
4. Disable the “Check mail messages for email scams” option and click on Close.

That’s it.

100% Distributed Web Hosting

Too bad it’s the bad guys.

As reported on DailyDave and picked up at SANS, Email Battles and elsewhere, there are phishers out there using a botnet (a network of infected “zombie” computers) not just to send emails, but to host the websites and the DNS for their scam.

Imagine what this technology could do for legitimate sites. It could potentially surpass Akamai’s system of worldwide mirrors. You could set up something like BitTorrent that would automatically mirror sites you’re looking at. Getting Slashdotted would actually improve a site’s response!

Stealing pop-ups from your bank

Here’s an online security story to freak you out: Security firm Secunia has found a loophole [Edit: originally linked to Yahoo! News] in basic browser window handling that can let any site plug its code into a pop-up window generated by any other site. That’s not just ads, that includes pop-up help files, password dialogs, you name it.

They even have a demonstration: Start the code going on their site, open up Citibank, then click on a button on the Citibank site and it’ll open a page from Secunia.

And it works in every major browser, for the simple reason that it uses standard functionality that no one has questioned until now: The ability to open a page in a particular frame or window. All you need to know is the name of that window, and you’re set. As long as it hides the toolbars (SOP for pop-up windows of all stripes), the user will never notice. There is a workaround, at least for Firefox and Mozilla users, but it’s ugly: prevent sites from hiding the location bar.

Actually, the functionality has been questioned before: last July, when Secunia found a similar problem in frames. The solution for that was to prevent a page in one window (or tab) from accessing frames in another. But it’s a little more challenging to decide which pages should be allowed to update a top-level window.

In the short term, sites wanting to protect themselves from being hijacked can probably help by randomizing the names of their pop-up windows. In the long term, browsers are going to have to figure out how to separate windows that should have the ability to load new pages from windows that shouldn’t, knowing that they’ll undoubtedly end up breaking some websites in the process.

(via The War on Spam)