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."

can this be?

Is it really possible to get even more spam using hotmail?

Re:can this be?

The headline would've worked just as well as:

"Your Rights Online: Hotmail Being Exploited by Spammers"

I suppose MS must be employing their new ActiveSpamXP.NET technology. Built on the proven reliability of ActiveSpam 6.0, it will make our spam receiving experience faster and more reliable.

Re:can this be?

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.

Re:can this be?

While you cannot block Hotmail's corporate addresses from spamming you with their really really handy newsletters about using their paid service to, erh, fight spam... you can set a custom filter to block any mail where the from name contains Hotmail.

I'm not sure, but I think that would block spam posing as Hotmail newsletters. It certainly keeps my newest Hotmail account clean.

I would do the same with my old (Pre-microsoft era, old enough to be comprised of my first name initial and full last name -- try that one today!), but I am using more custom filters than you can technically have for the free service since the introduction of the paid service. If I tried to change one of the filters to the aforementioned, half of my other custom filters would go out the window, but as long as I don't touch anything, it seems I can keep my filters... for now. I miss the pre-MSN days.

Oh I get it.

You expect Microsoft to be ahead of the spammers.

Re:I only use hotmail for online ordering

You might want to try out Yahoo's webmail service - it's noticeably quicker, and their spam blocking is really very good. I've had Yahoo accounts for at least couple of years and so far I've had absolutely no spam on them at all. Not bad considering my userIDs are based on dictionary words...

Re:Blame the original Hotmail owners.

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 [microsoft.com] don't use UNIX [microsoft.com] at all, do they? In fact, they never [google.com] did [google.com].

Re:Blame the original Hotmail owners.

crack team of MCSEs (if such a thing exists :-)

Of course they exist!

MCSEs only use the finest crack.

Re:ouch

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

Hotmail useless

I had a hotmail account once, but the spam level got so high that I abandoned it. It was about 10 times heavier than say Yahoo mail. But now Yahoo is spamming up also, I cannot even imagine 10 times that amount. I think that harddrive makers are in kahootz with spammers.

If you're using the free yahoo mail service, then

it isn't that Yahoo is "spamming up", it's that they've made "address blocking" as a part of their pay package. As a result you get more limited address-blocking capability with the free account, and it's easy to have them cycle through.

Also, I've noticed that some persistent spammers just get through, period, even with blocking [with no apprent change in the headers, at least none that are obvious]. :-/

Re:Hotmail useless

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

another vulnerability

If you check the box to list your new hotmail address on various partners' lists...ever wonder how that works?

InfoSpace was such a partner (maybe still is, but I don't work there anymore). Every so often Hotmail sends these partners a huge set of files. Basically, it's all the diffs, new users, etc.

All it takes is a few employees at a few such partners to copy the data and do whatever they want with it.

Of course, this is a very old problem...nothing unique to Hotmail...

Re:No Biggie

I always wondered how people get so many mail via hotmail while I do not

The only thing which I took care of, was to not click on "yes, send me spam from all advertisers", but that was a no-brainer. If you apply for spam, you will of course get it.

So far, I have my account for more than a year. I regularily send a mail once in 2 weeks to another account, with reply to keep it from expiring, but beside this I don't use nor advertise it at all. No spam. Zero. Nada.

It might be because I am non-american (so I am not a good target for american-only advertising).

Am I the only one with this "problem"?

Re:No Biggie

I also get no spam in my main hotmail account other than the occasional (monthly?) message from the hotmail system itself.

I did once set up an account at [e-mail], and the box was filled in less than a week, mostly with stuff addressed to a single person, so I think it's possible that many people get spam because they picked an address that was already in use in the past, but abandoned.

On a mostly unrelated note, I once had an address that was [e-mail], and got tons of mail from people at my ISP that were trying to send stuff to themselves.

Re:No Biggie

Like most people I suspect your grasp of "really obscure" is about as good as Microsoft's grasp of security through not documenting anything.

On March 6 I created a Hotmail account with a choice of name designed to be "really obscure". I have not had one single piece of spam arrive in that account. In 3 months, no spam. I've only used this account to test whether spammers use email addresses harvested from 551 User not local; please try [e-mail] SMTP responses (conclusion - no they don't)

Having see dictionary attacks on my own domain (and seen the bounces from dictionary attacks when spammers fake my source email address), I can conclude that geeks choice of obscure doesn't range far off science fiction character names.

As for this Hotmail exploit, I had been wondering why these spams were getting through my DNSBL lists - about the only spam that was.

Time to add hotmail.com to the baclklist until Microsoft fix this.

DAV as an integration method for outlook?

So they report that spam sent by means of this has the following in the header:

Received: from 202.144.44.81 by bay3-dav91.bay3.hotmail.com with DAV; Sat, 07 Jun 2003 23:33:24 +0000

and that the vulnerability was created to allow greater integration for Outlook users. Anyone know if all mail sent with Outlook through Hormail contains this in the header?

Re:DAV as an integration method for outlook?

and that the vulnerability was created to allow greater integration for Outlook users.

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

I am not trolling here, this is a serious question based on example after example of companies that want to standardize on Outlook. For instance, my wife's company (a large multi-national conglomerate which will go un-named) decided last year that they wanted to standardize on Outlook. Their support costs have supposedly skyrocketed and yet there is no discussion of using something else. What is happening here?

Re:DAV as an integration method for outlook?

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 [pmail.gen.nz] does much more than Outlook...
• PocoMail [pocomail.com] does everything you need, and is secure
• The Bat [ritlabs.com] is used by many, as a secure alternative
• Personally, I use only JBMail [pc-utils.com], which strips out HTML and has no scripting

Re:DAV as an integration method for outlook?

You know what I have been waiting for? Ximian Evolution for Windows. I don't know what I could personally do to contribute to this endeavor short of purchasing such a product or donating to the port....but that would be a completey sweet alternative...I love running Evolution on Linux machines, and I wish there was a convenient installer for Windows.

* btw - if there is a port and I am just not aware of it, someone please let me know.

Re:DAV as an integration method for outlook?

None of which have the calendar, collaboration or integration that Outlook has. Not one of them is suitable for a corporate environment without adding other programs in to make up for the lack...

Re:DAV as an integration method for outlook?

"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.

Spammers cutting and pasting???

Microsoft has created a grave spam threat with this vulnerability. Hotmail has always been a problematic spam source. The saving grace has been that the spam had to be transmitted manually, through a web form, so the sending rate was limited by how fast the spammer could cut-n-paste. Now that Microsoft has provided this new programmatic interface for spammers, that limit has been removed. Spammers may now script their spam runs--and they do--which has created a huge increase in spam transmitted by Hotmail.

So you are telling me that all the spammers out there who so gracefully manage to figure out how to avoid the plethora of filters designed to stop them, negotiate with bandwidth providers to keep thier accounts, and carefully hide thier irl addresses from everyone on earth with a spare brick and a good arm actually cut and paste thier e-mailed spam?

I don't buy it. An hour with a Perl for dummies book and the LWP doc's and any spammer can automate thier submissions.

Does the author really believe that these spammers are copy and pasting thier spams? I sure as heck don't.

Re: Spammers cutting and pasting???

> The bulk of it is 419 spam, which is reported to be largely done by hand by itinerant Nigerians.

Itinerants? I only get it from ambasadors, generals, and other important public officials.

Re:Three month old news

Hi. Welcome to Slashdot. You must be new here?

Spam control in Hotmail? Bought a bridge lately?

Not to totally deride Hotmail, but after having used it for several years, I can honestly say that it's probably the worst out of all free e-mail providers in terms of controlling incoming spam. Yahoo Mail blocks out a good 80-90% of incoming unsolicited mail, and hushmail.com is even better at it - I haven't gotten a single spam during my 6 months with them (so far at least). Add to that the ease with which Hotmail passwords can be hacked (trivial even for script kiddies), and after some consideration you might want to look at another provider.

And hey, it's owned by Microsoft! Grab your pitchforks! :)

Hotmail use

The best use for hotmail always has been: Use the account only for entering onto forms that require a live email address that info will be sent to immediately in response to the form being filled out. Then beyond that, don't even bother checking, just periodically empty the inbox all at once.

What kind of crack is that guy smoking?

You've been able to send email through OE and Outlook for years without utilizing the hotmail web interface. Outlook could easily be automated through COM to be a bulk mailer.

How is this any different than signing up for a standard throw away ISP account with imap or pop/smtp servers and using a bulk mailer in conjunction with it?

Wow..

Another function added at the expense of security and usability.

I get the distinct feeling that if Microsoft organised a piss up in a brewery there would be sausages, crisps, plenty of seating, a cool entertainment system, probably even a stripper... ...and a distinct lack of beer.

I thought this was news for nerds?

Why would a nerd ever use hotmail? Don't they all have their own domains?

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

...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

hotmail spam

Hotmail seems to receive more spam than other free email providers. I believe this may be due to how they handle recipient verification in SMTP. When a mail client attempts to send a message to an unknown username, the hotmail mail server will reply with an error message, indicating that the user doesn't exist. As a result, it is possible for a single spammer to spend some time just once to brute-force user names, and then distribute the list of known-good user names.

Yahoo generates the same reply regardless of whether the recipient exists or not. Thus, to guess user names, spammers would have to brute-force every mailing, as opposed to just the initial one like in the hotmail case.

Why hotmail would do something like this is completely beyond me.

Seems like a good time..

To plug bluebottle.com [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 [horde.org] as the actual email interface (I'm a much bigger fan of SquirrelMail [squirrelmail.org] 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.

hotmail... more porn for free

Ugh...
Hotmail supplies me with the following things:
Slashdot Updates
Porn

Oh yeah, and I occasionally get asked if my privates are O.K.

Check.
------
The movie of the summer [tripod.com]

Casaredmond

Ballmer: "I'm shocked--shocked!--to find that spamming is going on here."
Allchin: "The latest donation from the spammers, sir."
Ballmer: (sotto voce) "Oh, thank you very much." (to customers) "Get out! Everyone out at once!"

This article is flamebait-ish

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 [e-mail] 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 [sourceforge.net] 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 [zdnetindia.com] 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.

Imperial units?

From the article

...programatically generate a metric buttload of spam.

Anyone know what a metric buttload is in English/Imperial units? For some odd reason units(1) wasn't able to convert for me.

Since US butts are, on the whole, larger than in the rest of the world, I can guess that a metric buttload is larger than a US buttload.

This doesn't match my experience

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.

Hotmail users vs. the spammers...

Yes, Hotmail is a spamtrap. I've known about the chink in the proverbial armor for quite some time now. I've also gotten less than enthusiastic responses when I have tried to bring it to Hotmail's attention. (Really, the only reasons that I keep the account are 1: pure force of habit, and 2: it gives me an address to hand out to political mailing lists and such.)
Honestly, though, blaming Hotmail for this is pretty counterproductive. 99% of the time, parsing the header and tracing the return path reveals that the the displayed information was munged and spoofed beyond any resemblence to reality. I have yet to have a spam bearing a Hotmail "from" address actually be sent from a Hotmail account.

Yes, Microsoft is (probably) guilty of a multitude of evils. This, however, doesn't seem to be one of them. Hotmail spam is increasing, just as is all other spam, because there are enough idiots out there who actually will click on links in unsolicited e-mail to make it profitable for the [expletive deleted] who send the shite out in the first place.

hotmail

On the spamcop [spamcop.net] newsgroup this has come up several times, increasing frequently. After tens of complainst to hotmail, still the canned 'measures you can do to prevent spam' email returns. Nice to know they care about their soon to be blacklisting.

Security problem?

As much as I love to bash Microsoft, this isn't really a "vulnerability" in the normal sense. What they are saying is that when Microsoft lets you send mail through hotmail without a web browser, you can send mail through hotmail without a web browser. Duh. What's next, free POP/SMTP providers have a "vulnerability" that allows their users to send mail with their SMTP servers? And their claims of spammers otherwise being limitted to "copy and paste" is just ridiculous. Just because its a web interface doesn't mean it can't be scripted or can only be accessed by a normal web browser. Somehow I doubt that there are many spammers copy/pasting messages over and over into hotmail accounts.

hotmail leaks on purpose?

I created a hotmail account with an unusual name unlikely to be guessed by any kind of directory attack, and selected every privacy option I could find but within four hours I got spam.

How could that be without Hotmail leaking names?

The 65.54.*.* range

About a month ago my mailserver started to receive a lot of hotmail connections from the range 65.54.*.*., guess what the bay range servers inside hotmail.com. I contacted [e-mail], tried a few times to convince the drone at the other end that my mailserver was receiving a connection from a hotmail server every 20 seconds, but they didn't understand it. I mailed mailserver logs, explanations, links to threads about this on usenet, no clue. After a while I simply blocked all hotmail servers from my server. It's really weird that they have people on the abuse staff that do not understand what 'abuse' means or how to prevent it.

A week ago I removed the block to check if things had changed. To my suprise, no connection since. Apparantly MS has solved this problem finally (that is: installed the WebDAV patch that is what, 2 months old?).