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Catching Spam by Looking at Traffic, Not Content
Posted by
Zonk
on Thu Jan 25, 2007 10:43 AM
from the content-sniffing-doesn't-work-anyway dept.
from the content-sniffing-doesn't-work-anyway dept.
AngryDad writes "HexView has proposed a method to deal with spam without scanning actual message bodies. The method is based solely on traffic analysis. They call it STP (Source Trust Prediction). A server, like a Real-time Spam Black list, collects SMTP session source and destination addresses from participating Mail Transfer Agents (MTAs) and applies statistics to identify spam-like traffic patterns. A credibility score is returned to the MTA, so it can throttle down or drop possibly unwanted traffic. While I find it questionable, the method might be useful when combined with traditional keyword analysis." What do you think? Is this snake oil, or is there something to this?
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sounds good to me (Score:5, Insightful)
We can't do this on our personal or company internet connections because we only see individual messages coming from many different IPs, but on the other end of the connection, or even at the backbone level, this strikes me as a pretty solid solution. They could even just tag the packets with the evil bit [faqs.org] and let us decide if we want to filter them or not.
Re:sounds good to me (Score:5, Interesting)
A combination of policyd, postfix, spamassain and ids/bandwidth accounting software has turned it into something manageable, at least where I work. Customers are allowed say, 100 e-mails in a 30 minute time span. If they complain and have a real reason, we can adjust. This also makes finding users with pwned machines a lot easier.
Some of them now (the spam zombies) seem to be moderating their outgoing connections so that it's not so obvious but their volume is still substantial. It just never ends...
Parent
Re:sounds good to me (Score:5, Funny)
Parent
Has been done for a long time. (Score:5, Interesting)
My (previous) ISP did this several years ago. I found out when I was making a computer for a friend. At the time (this was a few years ago) I didn't yet know just how quickly an unprotected windows-box is owned by viruses. I thought I'd be okay for the time it takes to download a firewall. 20 seconds later I got a popup that I recognized as an infection, so I shut down the machine, and tried to get the firewall / AV-software with my other machine instead - only to be greeted by a screen where my ISP informs me that "By the look of your outgoing traffic, it would seem that your machine has been turned into a spam-bot by a virus, and your account will be automatically unblocked 1 hour after the suspicious traffic stops." This was followed by some generic instructions for virus removal.
Parent
Re:sounds good to me (Score:5, Insightful)
Actually, webmail can do one better: if a message is marked as spam at some point in time, the system can retroactively remove it from the Inboxes of the 'first few thousand unlucky recipients' (or mark it 'this may be spam', gray it out, etc., at the least). I don't know of anyone doing this, but I wish they would.
Parent
Re: (Score:3, Insightful)
Re: (Score:3, Insightful)
Then he asks to get port 25 unblocked. Or he's serious enough about his hobby mailing list to drop 8 quid a month for a dreamhost account (which isn't itself spam-free, but you know at least DH's nets aren't full of zombies). Or he switches to a web feed. There are solutions, but giving random strangers the benefit of the doubt isn't one of them.
If SPF and Domainkeys ever got any traction, then Challenge-Response
I don't need no steenkin' introduction (Score:3, Funny)
My ISP (and I mean mine, I'm a shareholder) doesn't give a flying fuck what I do with the bandwidth I paid for (and yes, I do pay). The fixed IP of my 2Mb ADSL suits my needs, and many of the needs of other business users we have as customers, extra QoS not required
Get off your high horse and suck it's cock.
This is painfully obvious and hopelessly naive but (Score:4, Interesting)
Re:This is painfully obvious and hopelessly naive (Score:5, Funny)
Parent
Re:This is painfully obvious and hopelessly naive (Score:5, Funny)
Parent
Re:This is painfully obvious and hopelessly naive (Score:4, Interesting)
Parent
No! (Score:4, Funny)
Thx in advance,
Parent
Re:This is painfully obvious and hopelessly naive (Score:4, Insightful)
Generally there's nothing to 'reply to' - To order the viagra you've got to go to a web site, or fax in an order - and all the latest 'pump and dump' stock-selling emails don't sell anything at all. They buy some stock, spam out their messages, then dump the stock when the price goes up. Often the company in question knows nothing about it.
Parent
I'll never stop (Score:5, Funny)
Parent
Re:I'll never stop (Score:4, Funny)
So do the world a favor... please...
Parent
Re:This is painfully obvious and hopelessly naive (Score:5, Insightful)
Parent
Re:This is painfully obvious and hopelessly naive (Score:4, Insightful)
Its similar to a pretty interesting conceptual innovation in medicine, when people realized that even excellent doctors will at some point make grossly negligent mistakes simply due to the shear amount of work they do (i.e. operating on people with paralytics but not analgesics). So the innovation is to make them make fewer decisions - machines that check settings before running, labels that a four year old could understand, arrows and other reminders liberally applied.
So similarly here, yes it's annoying that people continue to "fund" spammers, but education is not the answer. Because, unfortunately, the spammer's target market of "everyone in the world" will always contain enough people to make their trade profitable if all we rely on is good decision making on the parts of spam recipients. So the solution has to be technical or legal. And in that regard, another small step for man here.
Parent
Even if no one ever responds, it won't stop (Score:5, Insightful)
Even if no one ever responds, it won't stop as long as the people paying to have it sent think it works. It's like burning candles to St. Balderdash for scam marketing morons. As long as there is a steady supply of rubes who think that sending spam is their road to riches, and are willing to pay some brighter but no more honest spam lord to send their dreck to a bazillion hapless victims for them, spam will contine to flow.
This is true even if no one ever responds to, falls for, or even opens a spam message ever again.
--MarkusQ
Parent
Re:This is painfully obvious and hopelessly naive (Score:4, Interesting)
The spam-sending organization then shows them that they need to revise their message with a better subject line so more people opened the email. Another $1000 and more spam is sent, this time 0.7% of the people open the email.
Continue this until the advertiser runs out of money. If you have enough contracts for sending spam it matters not a whit if anyone buys the stuff at all. It is only important that people pay for it to be sent.
Parent
Re: (Score:3, Informative)
Re:This is painfully obvious and hopelessly naive (Score:3, Insightful)
Why can't people stop responding to spam in the first place? [...] If spammers made absolutely zero dollars for their efforts would they stop?
First off, if people stopped responding to spam, it wouldn't have any effect on phishing spam, since phishing is based on tricking the user into thinking it's legitimate mail rather than spam. Also, once you have control over an army of zombies, the incremental cost of sending one spam is zero. Even if the spammer thinks he's unlikely to make any money at all by s
unlikely indicators (Score:5, Insightful)
I think the question raises an interesting point: spams *behave* differently on the network than most legitimate emails. It may not be a perfect discriminator, but it sure might be a corroborative scoring aid. This reminded me of the controversy when Slashdot started using text compressibility as a metric for "lameness." I was a disbeliever, and still have my reservations about it, but as a part of the overall toolbox for filtering lameness, the technique seems to have value.
Re:And yet likely... (Score:4, Insightful)
because any email that from the 'Democratic People's Republic of $Country' is likely to be as bogus as the countries name. If a country needs to add 'Democratic' or 'Republic' to its name, you know something's wrong
- Central African Republic
- Czech Republic
- Democratic Republic of the Congo
- Dominican Republic
- Former Yugoslav Republic of Macedonia
And that's just the common names and not the official ones like "Republic of Ireland". Given that this is precisely the kind of verbose terminology that you would find in a genuine official email from a government body in such a country, I don't think that's going be suitable for anything other than a minor nudge towards spamminess.Parent
Places you don't want to be (Score:3, Insightful)
Central African Republic- Less than half the genocide of its neighbor in the congo.
Dominican and Czech Republics, and Macedonia- actual democracies.
So two of your five examples help prove my point- and when you start stacking adjectives together- like 'People's Democratic Republic of Korea' you know you've got one of the worst places to live on Earth.
Also, why on earth would you get an 'official governm
The best and worst places to be (Score:3, Insightful)
greylisting works (Score:2, Insightful)
OpenBSD's greylisting [openbsd.org] in spamd works wonders.
The problem with this (Score:5, Insightful)
Greylisting (Score:2, Informative)
request (Score:3, Funny)
we've got to keep this place organized
Yes and no - but a suggestion... (Score:3, Insightful)
OTOH, As part of a larger array of spam-fighting tools, okay - there's bits in there I actually like and which can be used as part of other solutions, if not used in the way suggested. As someone who runs a couple of MTA's on top of everything else I do around here, I always like to find new and interesting ways of stopping spam.
N.B., all that I ask is this: Please make it useful w/o sucking down resources or requisitioning another server. I detest external RBL's - please don't suggest anything that may have an overly-subjective and/or an overly-dependant basis like that. If it isn't RFC-compliant (yes, Verizon, I'm talking to YOU when I say that!), I won't go near it.
Satisfy those, and yes, I'm interested, as would lots of other SMTP-monkeys out here.
Obligatory (Score:4, Funny)
(x) technical ( ) legislative ( ) market-based ( ) vigilante
approach to fighting spam. Your idea will not work. Here is why it won't work. (One or more of the following may apply to your particular idea, and it may have other flaws which used to vary from state to state before a bad federal law was passed.)
( ) Spammers can easily use it to harvest email addresses
(x) Mailing lists and other legitimate email uses would be affected
( ) No one will be able to find the guy or collect the money
(x) It is defenseless against brute force attacks
(x) It will stop spam for two weeks and then we'll be stuck with it
( ) Users of email will not put up with it
( ) Microsoft will not put up with it
( ) The police will not put up with it
( ) Requires too much cooperation from spammers
( ) Requires immediate total cooperation from everybody at once
( ) Many email users cannot afford to lose business or alienate potential employers
( ) Spammers don't care about invalid addresses in their lists
( ) Anyone could anonymously destroy anyone else's career or business
Specifically, your plan fails to account for
( ) Laws expressly prohibiting it
( ) Lack of centrally controlling authority for email
( ) Open relays in foreign countries
( ) Ease of searching tiny alphanumeric address space of all email addresses
( ) Asshats
( ) Jurisdictional problems
( ) Unpopularity of weird new taxes
( ) Public reluctance to accept weird new forms of money
( ) Huge existing software investment in SMTP
( ) Susceptibility of protocols other than SMTP to attack
( ) Willingness of users to install OS patches received by email
( ) Armies of worm riddled broadband-connected Windows boxes
(x) Eternal arms race involved in all filtering approaches
( ) Extreme profitability of spam
( ) Joe jobs and/or identity theft
( ) Technically illiterate politicians
( ) Extreme stupidity on the part of people who do business with spammers
( ) Dishonesty on the part of spammers themselves
( ) Bandwidth costs that are unaffected by client filtering
( ) Outlook
and the following philosophical objections may also apply:
( ) Ideas similar to yours are easy to come up with, yet none have ever
been shown practical
( ) Any scheme based on opt-out is unacceptable
( ) SMTP headers should not be the subject of legislation
( ) Blacklists suck
( ) Whitelists suck
( ) We should be able to talk about Viagra without being censored
( ) Countermeasures should not involve wire fraud or credit card fraud
( ) Countermeasures should not involve sabotage of public networks
( ) Countermeasures must work if phased in gradually
( ) Sending email should be free
(x) Why should we have to trust you and your servers?
( ) Incompatiblity with open source or open source licenses
(x) Feel-good measures do nothing to solve the problem
( ) Temporary/one-time email addresses are cumbersome
( ) I don't want the government reading my email
( ) Killing them that way is not slow and painful enough
Furthermore, this is what I think about you:
(x) Sorry dude, but I don't think it would work.
( ) This is a stupid idea, and you're a stupid person for suggesting it.
( ) Nice try, assh0le! I'm going to find out where you live and burn your
house down!
Re: (Score:3, Interesting)
This form is for ideas that have been thought of before and have been discredited, but I'm not convinced yet that this idea wouldn't work. Here are the biggest objections you raised:
How? The method specifically mentions whitelisting, and only mailing lists or other "legitimate uses" (can't think of any myself) that involve thousands of recipients would be noticed by the proposed algorithm.
OPPOTUNITY. == DISCRETION REQUIRED == (Score:5, Funny)
OUR TECHNOLOGY DEPARTMENT HAS COME UP WITH A GREAT OPPUTUNITY TO STOP ALL YOUR SPAM. THIS TECHNOLOGY IS CALLED source Trust Prediction (STP). IT WORKS BASED ON identifying patterns and trends in real time AND IN THIS WAY PREVENT SPAM. HOWEVER TO MAKE PROFIT FROM THIS NEW TECHNOLOGYY WE NEED TO DO A PATENT APPLICATION. YOUR NAME CAME FORWARD AS AN EXCELLENT INVESTOR FOR THIS. WITH THE CURRENT RISE OF SPAM THIS TECH WILL BE REQUIRED QUICKLY BY A LOT OF PEOPLE.
I am only contacting you as a foreigner, I will use my influence to
effect legal approvals and onward transfer into your account At the
conclusion of this business, you will be given 50% of the total
PROFITS, 50% will be for me and my family AFTER DEDUCTION OF THE PATENT COSTS
. I await to hear from you.
Yours truly,
Mr.Barry Leoard.
FNB OF SOUTH AFRICA
THIS
IS MY PRIVATE EMAIL ADDRESS, YOU CAN SEND YOUR REPLY HERE:-
barryleonard@walla.com
Re:OPPOTUNITY. == DISCRETION REQUIRED == (Score:4, Funny)
There, fixed your spelling
Parent
Its not snake oil, but... (Score:5, Interesting)
effective in the long term. Getting around this type of filter (or delay) seems relatively simple
compared to the task of defeating the bayesian filters over the past couple years.
The lynchpin of greylisting is that legitimate mail will "try again" after being returned by the
server, while spam will not. The conclusion (which we hope is true) is that any mail that is
not re-sent was in fact spam. Never mind the danger that the assumption could be false and
legitimate mail gets lost -- how long will it be before spammers simply "re try" their spam --
or worse -- just send everything twice?
As with any attempt to modify behavior electronically -- behavior usually wins.
Re: (Score:3, Insightful)
What about SenderBase? (Score:4, Insightful)
This isn't a new concept. Our mail gateways already participate in something like this with IronPort's [ironport.com] SenderBase [senderbase.org] reputation filtering. 90%+ of our incoming mail traffic is dropped based on poor reputations scores without looking at anything more than the sender's address. So far, we've never had a false-positive that we know of, and only once, after many customers were made a part of a bot-net and started spamming, did SenderBase throttle traffic to one of the local ISP's. A quick call to their mail admins pointing out the problem and they were able to block those customers from sending mail until they were cleaned up and the reputation score climbed back up again.
It has really taken the load off our mail servers by blocking millions of connections. The rest, we run through SpamAssassin and everything works great!I am curious... (Score:3, Interesting)
Cheers.
Re: (Score:3, Informative)
Are any of you people still living with spam? Do we really need another solution?
Anyone who's a mail server administrator is living with more spam than you could probably imagine. During a four-week period, across two of the (very small) servers I manage, 38,728 connections were refused because of RBLs. Of the messages that were accepted, 8,102 were assigned a SpamAssassin score above 15 and sent to a system-wide quarantine folder that users never see. Another 13,619 messages were assigned a score between 5 and 15, and sent to a user-accessible quarantine folder for review. I use R
this and other effective weapons (Score:5, Interesting)
I work for a small email company we process millions of emails an hour inbound, but only a few million a day outbound.
Our most effective filters are:
connect/HELO restrictions: you can only get email into the environment if your IP address resolves to a FQDN.
HELO restrictions: if you connect using X different HELO strings, you are blacklisted. Spambots often randomize the helos, this blocks those.
Spamassassin at the client side, filtering email into various folders based on the score.
antivirus server that filters the few viruses that make it in, and phishing is filtered too.
The problem? All this doesn't catch enough of the spam. We still have loads of CPU dedicated to filtering spam, but something like this technique at the border will help, and I'll predict (based on experience watching the traffic and spam filtering graphs) that we could cut spam another 30% just by watching the curves and tightening the restrictions during those peaks.
Re: (Score:3, Interesting)
Re: (Score:3, Informative)
The only real solution to spam. (Score:3, Interesting)
Won't work. (Score:3, Interesting)
Won't work. It just means the owners of zombie PCs get big bills.
Re: (Score:3, Interesting)
That's not a bug, it's a feature.
Right now, the costs caused by Windows insecurity are passed on to me even though I don't run Windows. Passing those costs on to the people causing them would be much fairer.
Great idea, just several years late ;) (Score:5, Informative)
Ironport (recently purchased by Cisco for $830 million US) has been doing this kind of service for large providers for several years.
Their statistics site is publicly viewable, but using their stats requires a subscription fee.
http://www.senderbase.org/ [senderbase.org]
Its interesting to look at how well or poorly the MTA's you use are scored. All of the stats are gathered by the systems they sell to ISP's and enterprise customers. These boxes perform the spam filtering for that organization's customers and provide statistical data back to senderbase.org, which allows all Ironport customers to "know" about problems for all other Ironport customers.
The link to their PDF on their metric's is here:
http://ironport.com/pdf/ironport_wp_reputation_ba
We evaluated their system last year as a possible replacement for a third party spam/virus scanning provider and may end up purchasing their equipment once everything with the Cisco purchase shakes out. Their solution, while not perfect, behaves far better than some of the things that large service providers *coughAOLcough* have tried and are (or were when we tested) comparable to most of the content based scanning systems in terms of spam filtering with a lower rate of false positives.
Want to get rid of Spam? (Score:3, Insightful)
Send a URL in your text-only email if you want to check the email out in HTML...
Just a thought
The problem is that it is still filtering (Score:3, Interesting)
free, yet their router retains the default username and admin password. Spammers have programs that allow people to try to log in to these routers and use their embedded telnet commands to send spam without the knowledge of the computer owner or any program residing on their computer. The point is that the Internet can be compared more to "swiss cheese" rather than the "series of tubes" that the politicians use. There are many, many points of attack for spammers to use.
Filtering spam is much akin to a person who holds hands in front of his or her face while a bully is pummeling him or her. The person is likely to fend off blows from the bully, but some of the blows will get through. Once a spam is sent, even if properly filtered, the damage has already been done. Until very recently, all I had in my area was dialup. My program successfully filtered about 99% of the spam received, however I still had to wait about 30 minutes before I was able to view my legitimate mail. I lost 30 minutes of time that I could have been working on a client's problem, while the spammer lost nothing. I also lost a client because a program that I previous used labeled his email he sent me as spam. Again the spammer who spammed me lost nothing. Spammers are like bullies, they will not stop until people HIT BACK!
It is only when spammers have to deal with the large amount of bandwith used, the processing power to handle complaints, and the loss of sales that result from efforts to filter complaints will spam be much less profitable. The idea is to punch back and deter the bully. Sending complaints to the spammers' websites get them at their weak point - the place where they make contact with potential buyers. Several program have attempted to hit back, and 2 of them were very successful in doing so. However, like spammers, these programs had a weak point, and that point was the fact that they needed a central server in order to instruct each individual program. Now things are different. There are several projects currently underway to trade complaint instruction files via peer to peer networks. What this means is that there is no central server which spammers can attack in order to silence complaints to their websites. One such project is called SpammerSkewer, and it is an open source GPL program that is in alpha. The program can be found at http://spammerskewer.sourceforge.net/ [sourceforge.net]
It is also important to note that these new programs are not distributed denial of service programs. As for SpammerSkewer, it only receives instructions on how to complain. It does not initiate complaints. Only a user can initiate a complaint by either bringing up the complaint interface or by dragging an email into SpammerSkewer's spam directory. It is the Spammer who determines how many complaints are submitted to their websites. SpammerSkewer's author even provides a way for spammers to "opt out" from receiving complaints if they insert a header clearly labeling their email as spam. Another way they can opt out is by not sending spam in the first place. In a distributed denial of service attack, a person other than the one who controls a victim's website is the one that controls how many visits a site receives. With SpammerSkewer, it is the Spammer who sends out the spam that determines how many visits a site advertised via spam gets. The only sites that are put in SPammerSkewer's instruction files are those well known to be advertised via spam. Instruction files are also cryptographically signed in order to prevent tampering. I
Re: (Score:3, Interesting)
The company I work for contracts with advertisers to send out bulk mailings to our opted-in users.
And did they opt in by specifically requesting your mail, or implicitly as part of some other transaction? If it's the latter, you're a spammer. Die.
If people really want your content, offer an RSS feed. If nobody subscribes to your feed, they didn't want your content.