Google Mail Servers Enable Backscatter Spam 344
Mike Morris writes "Google email servers are responsible for a large volume of backscatter spam. No recipient validation is being performed for the domains googlegroups.com and blogger.com — possibly for other Google domains as well, but these two have been confirmed. (You can test this by sending an email to a bogus address in either of the domains; you'll quickly get a Google-generated bounce message.) Consequently spammers are able to launch dictionary attacks against these domains using forged envelope sender addresses. The owners of these forged addresses are then inundated with the bounce messages generated by the Google mail servers. The proper behavior would be for the mail servers to reject email traffic to non-existent users during the initial SMTP transaction. Attempts at contacting them via abuse@google.com and postmaster@google.com have gone unanswered for quite some time. Only automated responses are received which say Google isn't doing anything wrong."
*goes change his gmail password* (Score:5, Interesting)
Seriously though, there's something else that bothers me about gmail (not the only one to do it): that apparently anyone can get your contact list if they have your address.
Ever happened to you? I was signing up on a music website with a gmail address, and then they asked me if I wanted to send invites to all my contacts, which magicaly appeared on their page. Even if it is apparently a common practice, I find it very disturbing.
just point it out to them more clearally. (Score:5, Interesting)
to: bogus@[domain]
You have issues.
If they have back scatter, they get it. If they don't have back scatter, they don't.
A suggestion for Gmail spam-fighting (Score:5, Interesting)
soaked. Even their filtering is having troubles with false positives
and false negatives--and the spam is just increasing. Therefore I
think Google should act more aggressively to drive the spammers away
from Gmail.
My latest anti-spam idea is a SuperReport option. (Kind of like
SpamCop, but not so lazy.) If you click on the SuperReport option,
Gmail would explode the spam and try to analyze it for you to help go
after the spammers more aggressively. Here is one approach to
implementing it:
The first pass analysis would be a low-cost quickie that would also
act like a kind of CAPTCHA. This would just be an automated pass
looking for obvious patterns like email addresses and URLs. The email
would then be exploded and shown to the person making the report (=
the targeted recipient of the spam AKA victim). The thoughtful
responses for the second pass would guide the system in going after
the spammers--making Gmail a *VERY* hostile environment for spammers
to the point that they would stop spamming Gmail.
For example, if the first pass analysis finds an email address in the
header, the exploded options might be "Obvious fake, ignore",
"Plausible fake used to improve delivery", "Apparently valid drop
address for replies", "Possible Joe job", and "Other". (Of course
there should be pop-up explanations for help, which would be easy if
it's done as a radio button. Also, Google always needs to allow for
"Other" because the spammers are so damn innovative. In the "Other"
case, the second pass should call for an explanation of why it is
"Other".)
If the first pass analysis finds a URL, the exploded options should be
things like "Drugs", "Stock scam", "Software piracy", "Loan scam",
"419 scam", "Prostitution", "Fake merchandise", "Reputation theft",
"Possible Joe job", and "Other". I think URLs should include a second
radio button for "Registered Domain" (default), "Redirection",
"Possible redirection", "Dynamic DNS routing", and "Other". (Or
perhaps that would be another second-pass option?)
If the first pass finds an email address in the body, the exploded
options should include things like "Fake opt-out for address
harvester", "419 reply path", "Joe job", and "Other".
At the bottom of the expanded first pass analysis there should be some
general options about the kind of spam and suggested countermeasures,
and the submit SuperReport button. This would trigger the heavier
second pass where Gmail's system would take these detailed results of
the human analysis of the spam and use them to really go after the
spammers in a more serious way. Some of the second pass stuff should
come back to the person who received the spam for confirmation of the
suggested countermeasures.
Going beyond that? I think Gmail should also rate the spam reporters
on their spam-fighting skills, and figure out how smart they are when
they are analyzing the spam. I want to earn a "Spam Fighter First
Class" merit badge!
If you agree with these ideas--or have better ones, I suggest you try
to call them to Google's attention. Google still seems to be an
innovative and responsive company--and they claim they want to fight
evil, too. More so if many people write to them? (I even think they
recently implemented one of my suggestions to improve the Groups...
However, it doesn't matter who gets credit--what matters is destroying
the spammers.)
250 Accepted (Score:5, Interesting)
Yes, mail to an unknown recipient should be rejected with a 550 code during the initial SMTP dialogue. But not only that - lots of people believe that *any* message you don't intend to deliver should be rejected during the SMTP dialogue. The current fashion is to say "250 OK" and then silently delete the message later, which is wrong.
I hate to toot my own horn here, but I wrote tarmail [ablative.org] with this express purpose in mind (among others). GPLed and everything. Messages that you won't accept get rejected during the SMTP dialogue.
If you don't like my MTA, then please feel free to mod this down so that others won't be needlessly bothered. But I really to believe that Tarmail is the right answer to this specific problem. Thank you for your time.
Google Groups must DIE (Score:3, Interesting)
Re:250 Accepted (Score:3, Interesting)
Re:*goes change his gmail password* (Score:5, Interesting)
LinkedIn asks me if I want to "connect" to certain people that I know for sure my only contact with them has been through mail on my gmail account. LinkedIn *can* mine your gmail account for you if you provide your account info to them, but I certainly never used that feature, so it was a bit alarming to see all of my gmail contacts showing up.
Personally, I don't care if they are not the only ones to do it. They shouldn't be giving out our personal info. I did expect them to use my info to provide context-sensitive ads, but I did not expect them to share my info with other companies without my explicit permission.
Not to mention, if you and I both saw it on sites that ostensibly have no relationship with google, it's possible that anyone that can hook to their Soap API can get your contact list.
Re:250 Accepted (Score:5, Interesting)
Since SMTP is defective by design, this is an acceptable response. Doing anything else allows spammers to confirm valid accounts using dictionary attacks.
It is not that easy.... (Score:5, Interesting)
If the sender address is legitimate, but a relay is in the transmission chain, you have only bad choices: Silent drop may cause problems for legitimate emails. Initial bounce causes the observed problem, once removed and with real-time characteristics. The observed delayed notification behavior at least has the advantage that you can control the rate these messages are outgoing. A good strategy would be to intitially send one of these and then accumulate these per sender messages over, say 24h and send only one further notification per day. Incidentially, this strategy is something known to most people that ever implemented automatic notification emails on system failures...
I think there is just no good way to deal with this issuse, as long as open, badly configures relays are around. It is also quite possible that the gmail designers never anticipated this and not are not readily able to respont in an adequate fashion (see the 24h accumulation, e.g.). That would possibly indicate a lack of competent security people involved in the design process. As these people are scarce everywhere, Google will also likely not have enough of them.
On my own mailservers (small), I use silend drop for relay requests (which is definitely a good idea) and "drop into spambox" for unknown destinations. I look over these occasionally, and I have found legitimate email in there.
I do agree that initial bounce sounds like the right strategy, but unfortunately it does have serious problems.
Re:250 Accepted (Score:5, Interesting)
In fact setting up ClamAV and SpamAssassin alone is orders of magnitude more complex.
I might argue that if you have a hard time understanding the postfix manual you have no business running a mail server.
In any case, I wasn't trying to compare, just trying to understand why it was worth the effort of yet another SMTP server.
We block hosts that send backscatter (Score:1, Interesting)
We run the WPBL [wpbl.info] blocklist, which is a small but relatively well established blocklist service.
Our policy is to treat backscatter as spam, and we do block some hosts due to this backscatter. Google's mail servers are whitelisted at our service, as are other major ISPs, so realistically Google would not get blocked.
However there are many minor mail servers on the internet that constantly spam us with backscatter, and these hosts do get blocked. Some of our members receive thousands of backscatter spam daily. In the last few days in fact there has been a flood like we've never seen before, mailbombing all coming from mail server backscatter.
If you run a mail server, I encourage you to study and understand backscatter. Unless you have put measures in place to avoid being part of the problem, I can virtually guarantee you that you are sending out backscatter. Go right now and run a quick mailq and see if there are a lot of mailer errors in your queue to fake addresses... if there are, you are sending backscatter. It is very common, and very annoying. It is preventable with the right configuration. I have argued this with plenty of admins, but I guarantee you that you can avoid sending backscatter with a proper configuration.
Backup and secondary MX hosts do not have to be vulnerable by design. Solutions: 1) distribute valid recipient lists to MX's and reject mail at the correct transaction, or 2) check and respect SPF for the sender, or 3) run an anti-spam filter, check heuristics, and only send back mailer errors on high confidence ham.Re:And google wonders why ... (Score:1, Interesting)
Re:Mod Parent Up (Score:2, Interesting)
Quite handy to simply double-click and open Gmail and iG in separate windows, without being logged in on Firefox.
Why not just go back to Blue Security Model? (Score:3, Interesting)
It was the ONLY thing that worked. In fact, it worked so well that the spammers had to declare open warfare against them.
Hah! Let's see them try THAT with Google. Oh, and seeing all of Google's Gmail customers becoming virtual BlueFrogs by default would be pretty cool, too!
Not Gmail. (Score:4, Interesting)
I tested this on Google Apps for my (company's) domain.
Turns out that yes, they will drop it on the floor if you give them an invalid address. It's probably not gmail.com, and definitely not yourdomain.com -- but rather, blogger.com and googlegroups.com -- which seem to be accepting mail and bouncing, rather than rejecting via SMTP.
A quick demonstration:
As you can see, it not only dropped my message on the floor, it also demanded brackets around the address -- something Postfix and Exim do for me, and I think even Qmail tolerated addresses without brackets.
I imagine it works pretty much the same way for gmail.com, so if you're going to take advantage of the bouncing to have Google DoS Google, keep that in mind. Send mail from bogus_01234@blogger.com to alsobogus_56789@googlegroups.com. (I think adding a GUID to it would be a nice touch, thus guaranteeing that it will never match an actual address.)
Re:*goes change his gmail password* (Score:5, Interesting)
Seriously, I barely trust myself with my personal info -- why trust a complete stranger (or set of strangers) that are based out of a country where the gov't can just lean on a company to get private data?
The staff at Facebook don't give two shits about privacy, otherwise all those stupid "apps" which you add to your profile wouldn't be able to spider your friends or send them stupid form letters to encourage them to allow/add them (furthering the data-mining by the app writer). Try turning the privacy settings up by disabling everything when adding an app. It won't let you, because then the app "wouldn't work" correctly.
Behaviour isn't WRONG wrong, but Not Good. (Score:3, Interesting)
There are some problems here.. First of all, what if the server in question doesn't know what users are 'good' or not? Say, if it's a backup MTA? The non-primary MX? Which are receiving mail due to the primary being down?
Quite common for them not to know about all the email accounts.
Now, problems with backscatter has been there for a while. It's certainly not nice, but there are only so many things one can do. If you read the original RFCs, Google's behaviour is entirely acceptable. Unfortunately the original RFCs for SMTP was written way before spam became a problem...
Other MTAs are "just as bad". Look at qmail for example. This is default behaviour in qmail. It'll accept any email without confirming whether the recipient exists or not (to prevent in-line data-mining of what accounts are there and what accounts aren't there). If the email is to a bogus recipient address, qmail will generate a bounce.
This bounce will go to the From: address.
And that's QMAIL - which is considered a secure mta.
Then you have the same problem, as I've mentioned, occuring when you've got a secondary MX which doesn't have a list of users. The choices for the MTA is to either create a bounce and inform the sender that the recipient doesn't exist - or you might silently discard the message. Neither are good options.
SMTP is kind of broken. Don't blame google for it. Different people consider different things best practices. I don't agree with googles practice in this particular case, while others would claim it's the only proper behaviour.
and? (Score:3, Interesting)
Google clueless? (Score:3, Interesting)
From Wikipedia:
"Since these messages were not solicited by the recipients, are substantially similar to each other, and are delivered in bulk quantities, they themselves can qualify as unsolicited bulk email or spam. As such, systems that generate e-mail backscatter can end up being listed on various DNSBLs and be in violation of ISPs Terms-of-Service for being abusive."
So please help Google get a clue: look in your (spam) folder and if you find any of the emails mentioned, report it to spamcop.com. If everyone just submits one report, I am sure this will get resolved (Google will not let themselves be blacklisted for long for non-complience).
By the way, backscatter spam is a serious problem, and I am quite appeled when even ivy league school admins have no clue about it... There should be a shamelist for sysadmins as well who do not cooperate with efforts against spam (even if only out of ignorance/stupidity or even more so).
Re:Mod Parent Up (Score:3, Interesting)
Not particularly secure, that...
Re:Mod Parent Up (Score:3, Interesting)
You want secure email you GPG to encrypt it.
They're following RFC (Score:1, Interesting)
Re:Nothing new here... (Score:1, Interesting)