Spammers Exploiting Hotmail Vulnerability

chip rosenthal writes "Notice more Hotmail spam in your inbox recently? There is a good reason for that. In March, spammers discovered a new vulnerability in the Hotmail service that allows them to script their spam sending. So far I've seen a 2200% increase in Hotmail spam as a result. We're now at three months and counting, and the problem only seems to be getting worse."

Comments

Re:ouch

[jqh1]

go for the bonus round by getting a disposable email account (eg spamgourmet.com) to protect your new address.

I reported this problem to them some time ago...

[Yonder Way]

...and they shrugged it off, claiming it wasn't their problem. Hotmail actually pointed the finger at MSN, and MSN wasn't responsive when I included them in the loop.

Here's an example of the kind of brush-off I got when reporting this to Hotmail. Note that I've reported the issue several times, tried to have it escalated as I suspected it was a hole in their DAV implementation. Here's what I would get back from them:

Hello warthog,

Thank you for writing to MSN Hotmail.

This is Alvin and I'm writing in response to your complaint.

I have checked the mail including the headers and it appears that the
mail passed through a Hotmail server. However, kindly note that this
does not mean such e-mail originated from our domain.

Sometimes, e-mail delivery between different domains are relayed
through other servers. This is the reason why a Hotmail server appears
in the mail header. It is possible that your ISP or e-mail provider
employs such method.

I understand how it feels when an illegal activity has not been given
proper attention. However, we're only allowed to investigate Hotmail
members. In this case, I strongly suggest that you contact the Help
program or the Abuse section of the domain from which the unwanted
e-mail originated .

Sincerely,

Alvin F.

MSN Hotmail Customer Support

Re:Hotmail useless

[illuvata]

for all the people that obviosly didn't RTFA or even the summary, this is not about recieving spam on your hotmail account, but geting spam from hotmail accounts.
basicly, before you spammers had to go through the slow web interface to send spam, now they can automate the process

Re:DAV as an integration method for outlook?

[bigberk]

So, Outlook is this huge pipe for virii, worms and spam leading me to wonder.....why is anyone still using Outlook?

Excellent point. Especially amazing when so many free Windows alternatives exist:

• Pegasus Mail does much more than Outlook...
• PocoMail does everything you need, and is secure
• The Bat is used by many, as a secure alternative
• Personally, I use only JBMail, which strips out HTML and has no scripting

Re:DAV as an integration method for outlook?

[Anonvmous Coward]

"So, Outlook is this huge pipe for virii, worms and spam leading me to wonder.....why is anyone still using Outlook?"

1.) They don't necessarily need to use Outlook to be exploited. If a file has the extesion .EML, it opens Outlook Express. If you have Outlook 2000 (harder to exploit btw, I've had it since it came out and nobody in my company has been hit by a worm through it) and somebody sends you a message with a .EML attachment, opening the attachment fires up the much more vulnerable Outlook Express.

2.) People can be using any email app and still get tricked into opening a trojan. Since Outlook Express is on everybody's Windows machines, then it can still be used as a conduit to send stuff back out. Most of the attempts I've seen involved opening stuff that has nothing to do with what e-mail app you're running. Remember "pretty park.exe"?

I'm not defending MS here, Outlook Express has created a nasty situation for Windows users. You don't even have to use OE to have it bite you in the ass. Uninstalling it's not painless either. I tried to do that once, and it killed Outlook 2k by wiping out a common DLL that they use. Doh. (Note: I haven't tried uninstalling OE and installing O2k.)

Here are a few things you can do to solidify yourself:

- Remap the .EML extension to open Notepad instead of Outlook express.

- If you're using Outlook 2000, set its 'attachment security' to high. While you're at it, go through it's zone security and turn off everything. You don't need 'ActiveX Controls marked as Safe' to be enabled, for example.

I acted as my company's sysadmin for a couple of years. Back then, we were all running Windows 2000 and Outlook 2000. As mentioned before, I never had to deal with the cleanup of a virus. All I really had to do was go through that little checklist. If I hadn't done that.. well who knows? I probably wouldn't have so many posts on Slashdot. I'd be busy working or something. Heh.

Seems like a good time..

[msimm]

To plug bluebottle.com. Their 'smart' spam filtering system includes a challenge-response type system to verify the legitimacy of the account and an allowed list. I've been using it for about 2 weeks and like it so far (I get over a hundred pieces of crap a day at my old account).

Couple of nits are it is slow as hell to log into (they are in Australia and supposedly upgrading their system to fix this) and it uses Horde as the actual email interface (I'm a much bigger fan of SquirrelMail and always thought Horde needed a serious facelift).

Of course the upside is I haven't had a single piece of spam and I really like logging in and knowing that if I have new mail its from people I want to hear from.

Here's their marketing spiel:

Bluebottle stops spam.
Bluebottle's open-source technology is 100% effective in blocking unwanted email. It is the only system that can effectively protect a user from spam while ensuring all legitimate email is received.

Bluebottle is easy to use. When Bluebottle receives an email from an address or domain not on your âAllowed' list, a verification request is sent asking the sender to verify themselves in one of two ways. The required response to these verification requests automatically places the sender's address on your âAllowed' list, and the email is delivered to you without delay.

Once the sender's address is on this list, they can email you as they would normally. The advantage is that you ONLY receive email from allowed senders.

Effective.
To avoid identification, spammers commonly use forged or fake addresses. Consequently, the verification request is never seen or responded to, so spammers can't infiltrate your allowed list. That means you'll no longer receive annoying, unwanted email.

Manageable.
Bluebottle is easy to manage. Simply add your known contacts to your âAllowed' list so they can avoid verifying themselves. And even if legitimate senders do need to verify themselves, it's quick and easy to do so.

If you're sending an email, Bluebottle automatically adds the recipient's address to your allowed list to avoid a request being sent when they reply.

Protective.
Bluebottle applies the verification process to your existing email, including Hotmail, by checking your accounts through its servers. Email from known senders is delivered to your account without delay. Unknown email is placed in the pending queue to await verification. You can access your spam-free email through Bluebottle's webmail interface or via pop using any email client.

This article is flamebait-ish

[skookum]

There are several things that it appears most people do not understand about hotmail or email in general:

• You cannot trust the From: line! A whole lot of spam looks like it's from a Hotmail account based on the email address in the header. But this is almost always forged, and it says nothing about the actual service used to send the email. Most times, the mail is sent via an open proxy, usually in an uncontrolled network. Korea, China, Argentina, Nigeria, Brazil are all very good sources of open proxies. In other words: Do not think for a single moment that because the spam says it's from abcd123@hotmail.com that it had anything whatsoever to do with Hotmail!
  
  
• Mail sent using HTTPMail, the proprietary WebDAV interface that this article referrs to, will always have an easy to spot Received line that contains "with DAV;". It will also have an X-Originating-IP: [a.b.c.d] header that can be trusted. Note that sometimes the spammer will try to forge a fake X-Originating-IP, but it will usually either have the wrong capitalization (Ip vs. IP) or it won't have viable IP address numbers, usually with dotted quads greater than 255. It will also usually have an X-Originating-Email header that identifies the actual account name. Because of this, anyone dumb enough to spam with this method gets the account they used shut down almost immediately. In contrast, open proxies leave no evidence whatsoever of the actual originating party of the message.
  
  
• It is hardly a secret. For example, there's an open-source Mail plug in for OSX that lets one send/receive mail with HTTPMail. Additionally, there are Windows utilities that create a pop3-HTTPMail gateway, allowing you to read hotmail that way.
  
  
• As of March of this year, you can only send 100 emails per day per account using this method. Slashdot covered the story when the change was made. Here's a link to one version of the announcement.
  
  
• For the above reasons, you won't get a lot of spam from this service. I just grepped my known-spam folder with about 2000 messages for the last 6 months or so, and found FOUR such HTTPMail-delivered spam -- and they were all from msn.com addresses/accounts, not hotmail.
  

So please, I know slashdot will take any opportunity it can get to Microsoft-bash but in this case the blogger is pronouncing the sky to have fallen when it has not. The fact is that this service IS traceable and IS throttled, two aspects which make it relevent only to the newbie spammer that doesn't know what he's doing.

Re:can this be?

[sleeper0]

This exploit appears to allow you to obscure your ip address as well. I didn't see any mention of this in the linked article so i figured it was worth mentioning. About a month ago i recieved a spam complaint from our ISP about mail sent from a machine in our IP block:

Received: from 64.84.xxx.xxx by bay3-dav112.bay3.hotmail.com with DAV;

After investigation it didnt seem like the spam had come from there, there was no evidence of a break in or that anyone had used it to send spam. While we were investigating we changed it's IP adress and never bothered to change it back, but we've still been given 3 more copies of current spam showing this IP address thats not even in use anymore.

By the way, I thought the article was pretty retarded standing on it's soap box about horrible microsoft security blah blah blah. The entire industry has problems with security, singling one company out is just petty. I've certainly had a lot of linux security updates I've needed to install over the past year, its nothing exclusive to one camp.

Also i think he was exagerating the effect of this bug.

I checked my spam that i've gotten since 5/1/03:
3467 pieces of spam
5 pieces of DAV spam

hardly a substantial amount.

This doesn't match my experience

[babbage]

I've just grepped my spamtrap directory for 'with DAV', as the linked article suggests should be seen in messages delivered using this exploit. For background, here's a little ascii chart of my month over month spam trends (line length is divided by 25):

0165 Jun xxxxxx
1602 May xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxx
0734 Apr xxxxxxxxxxxxxxxxxxxxxxxxxxxxx
0439 Mar xxxxxxxxxxxxxxxxx
0289 Feb xxxxxxxxxxx
0236 Jan xxxxxxxxx
0283 Dec xxxxxxxxxxx
0189 Nov xxxxxxx
0417 Oct xxxxxxxxxxxxxxxx
0349 Sep xxxxxxxxxxxxx

Clearly, I for one have been getting a surge in spam lately, which might possibly be sloping back down after last month's spike, but it's too early to tell yet.

In spite of that, of the nearly 3000 spams I have received since march, only seven match the pattern with DAV in the message headers. That bears repeating: I have received only seven instances of this exploit, vs. 2940 overall spams since March. Further, I only see 72 messages that have a hotmail.com server on their received headers at all -- most of the time I get "from Hotmail users" it's almost always forged.

Anyway, the first message to mention "with DAV" was sent March 25th, which fits the timeline this guy describes. On the other hand, the rest of my data massively disagrees with the 2200% spike that is suggested in the linked blog -- it seems to me that 0.238% of the spam I'm getting is due to this mis-feature, not 2200%.

Now granted, the two of us are the only two data points that I know of so far, but the results that we're seeing are so wildly out of step that I wouldn't think people should draw conclusions from this. Two completely conflicting measurements can't show us any kind of pattern.

The spam sky may be falling, but this isn't one of the falling pieces you need to keep an eye out for as near as I can tell.

Re:Blame the original Hotmail owners.

[grahamlee]

FWIW, Hotmail ran on BSD for a number of years, before Microsoft bought it out. They then sent a huge crack team of MCSEs (if such a thing exists :-) in to switch everything over to Windows, and they did everything apart from the advertising servers. It was run like this for a couple of years, then some Linux fanboi said "look! Microsoft use Unix!" and they changed the ad servers too. I've had my Hotmail account for around six years, and have been receiving stupid volumes of spam for about three years. Even when Microsoft took over, it was a useful service for a few years.

Of course, we all know Microsoft don't use UNIX at all, do they? In fact, they never did.