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Google Mail Servers Enable Backscatter Spam
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*
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.
Don't take my posts literally; it's just code to control my botnet.
forged from: abuse@[domain]
to: bogus@[domain]
You have issues.
If they have back scatter, they get it. If they don't have back scatter, they don't.
Basically Gmail is losing value for all of us as it becomes spam
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.)
Freedom = (Meaningful - Coerced) Choice != (Speech | Beer^2), and sad sock puppets' bad mods avail them naught.
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 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 is one of the biggest culprits in the utter destruction of the highest traffic Usenet discussion newsgroups. The volume of spam that comes from those servers is ridiculous, not to mention all the former AOL idiots that were the scourge of the groups.
There are three possibilities for email to non-existent addresses: Silent drop, initial bounce and delayed notification. All have problems.
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.
Most ACs are not even worth the keystrokes to insult them. Be generically insulted by this and ignored otherwise.
We run the WPBL 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.- allow backscatter spam
- ???
- profit!
Indirectly, yes. Fixing the backscatter would mean tasking people to spend time on it. By not fixing it, they can have those people work on some adsense drudgery that will make Google more money.In addition to all that, I sandbox all my Google activities into Mozilla Prism 0.9 with several separate profiles.
Quite handy to simply double-click and open Gmail and iG in separate windows, without being logged in on Firefox.
Why doesn't Google go with the Blue Frog/Security Method?
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!
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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.)
Don't thank God, thank a doctor!
This behaviour isn't WRONG wrong, but it's not very good practice any more.
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.
"Rune Kristian Viken" - http://www.nwo.no - arca
Say my manufacturing plant is "in beta". Does that excuse it belching out toxic smoke and polluting the atmosphere? No. Gmail being in beta doesn't give them a licence to belch out spam, either.
I was under the impression until now that Google (as a business and its employees) are technically quite savy. Seems quite strange that they are clueless about spam.
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).
Except POP3 is generally transmitted in the clear unless configured otherwise.
Not particularly secure, that...
SMTP protocol, you know, email, is transmitted in clear text. So why does it matter if POP3 would be transmitted clear or not? The password doesn't need to be transmitted in clear text, just a hash.
You want secure email you GPG to encrypt it.
What they're doing is not wrong according to RFCs. It is wrong according to current best practices invented in the face of truck loads of SPAM. So, technically, they're correct in saying they're not doing anything wrong. That doesn't mean I agree with that statement though. I have a process that dumps our corporate LDAP database to a "relay-recipients" file every night so that Postfix knows what it's allowed to receive and what it should reject with a 550. The previous administrators did not have this configured and we ended up on Spam Cop's list several times before we finally got buy-in to make the requisit changes. We also do some basic checks for message correctness, which drops a whole lot of stuff right up front with a 550. As an example, no FQDN with the HELO/ELHO command ... 550 it is.
Vint Cerf was a well known apologist for spammers when he was at MCI. There's a good reason the mail community protested when Cerf was given the Turing Award. He's disgraced himself, it's just too bad more people don't know about it.