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Botnet activity warning

A bit of advice from the folks at the CBL, posted with permission and some light editing. I’ve been seeing some folks report longer connection times at some places, and this might explain some of it. It’s certainly possible, even likely, that the large ISPs are getting a lot of this kind of traffic.

A botnet, likely a variant of cutwail, has been for the past several years been specializing in using stolen credentials, doing port 25/587 SMTP AUTH connections to the spoof’d users server, and attempting to relay thru the connection to elsewhere. They will also, in some cases, attempt to log into the MX IP using a brute force attack against the email address. Other miscreants try the same thing with IMAP or POP or even SMTPS.
If they manage to compromise an email account, they use the account to send spam. For corporate accounts they can steal employee identities, request wire transfers, and send out corporately authenticated spam. If they get it, game over, the whole account is compromised and they can and do wreak havoc.
This has been going on for a couple of years, and now is the largest volume of spam from botnets. Cutwail is not the only botnet doing AUTH attacks, but appears to be the most prolific. Attacking POP and IMAP appears to be more recent, and is more related to spear-phishing (spamming executives) and other bad things.
In the last month or two, the behavior has changed a bit. The infections are trying to establish as many connections simultaneously as it can get away with. This is similar behavior to ancient or unpatched versions of qmail. This is swamping some servers by tying up a significant number (or even all) of the TCP sockets available.
The CBL is recommending that folks check their mail servers. If the mail server has a “simultaneous connection per IP limit”, it should be set to some limited number. If it’s not set then set it. Otherwise, your server is at risk for being unable to handle real mail. Make sure your IMAP and POP are secured as well as they are being targeted, too.
The XBL can also help with this. But securing your server is the first step.

SpamCannibal is dead

The SpamCannibal blacklist – one that didn’t affect your email too much but which would panic users who found it on one of the “check all the blacklists!” websites – has gone away.
It was silently abandoned by the operator at some point in the past year and the domain registration has finally expired. It’s been picked up by domain squatters who, as usual, put a wildcard DNS record in for the domain causing it to list the entire internet.
Al has more details over at dnsbl.com.
If you run a blacklist, please don’t shut it down this way. Read up on the suggested practice in RFC 6471. If you just can’t cope with that consider asking people you know in the industry for help gracefully shutting it down.
Blacklist health checks
If you develop software that uses blacklists, include “health check” functionality. All relevant blacklists publish records that show they’re operating correctly. For IP based blacklists that means that they will always publish “127.0.0.2” as listed and “127.0.0.1” as not listed. You should regularly check those two IP addresses for each blacklist and if 127.0.0.1 is listed or 127.0.0.2 isn’t listed immediately disable use of that list (and notify whoever should know about it).
For IPv6 blacklists the always listed address is “::FFFF:7F00:2” and the never listed address is “::FFFF:7F00:1”. For domain-based blacklists the always listed hostname is “TEST” and the never listed hostname is “INVALID”. See RFC 5782 for more details. (And, obviously, check that the blacklists your software supports out of the box actually do implement this before turning it on).
If you use someone else’s blacklist code, ask them about their support for health checks. If your mail filter doesn’t use them you risk either suddenly having all your mail go missing (for naive blacklist based blocking) or having some fraction of wanted mail being delivered to your spam folder (for scoring based filters).

UCEProtect and GDPR fallout

First thing this morning I got an email from a client that they were listed on the UCEProtect Level 3 blacklist. Mid-morning I got a message from a different client telling me the same thing. Both clients shared their bounce messages with me:

#GDPR

Twitter has some opinions on #GDPR.

— @rianjohnson (Yes, the director of The Last Jedi)

I subscribed to what?

Tomorrow is GDPR day. That’s the day when the new Global Data Protection Regulations take effect in the EU. I’m sure everyone reading this blog has seen dozens, if not hundreds, of blog posts, articles, webinars, and guidance docs about how to comply. I’m not going to rehash it because, other folks know this better than me.
There are a some things I’m finding fascinating watching this whole GDPR thing.
First, the number of companies who have my addresses and I don’t know why. Take Newsweek (yes, the magazine people). They’re sending GDPR notifications to my LinkedIn address. I can’t figure out why they’re harvesting / buying addresses from LinkedIn. Then there’s SALESmango who are some company that started spamming me a few years ago and refuses to accept unsubscribe request. They’re sending me opt-in requests. Yeah, no, go away. I told you to stop, but wow, you won’t.
Another interesting piece is just how much I’ve signed up for over the last 18 – 20 years I’ve been using this set of addresses. Wow. So much mail. And, generally, I thought of myself as relatively careful in who I gave email addresses to. I don’t normally go around dropping addresses into forms but even a couple a month adds up over 20 years.
Then there are the companies violating CAN SPAM in one way or another. Sending mail to unsubscribed addresses and refusing to include an opt-out link are the two things I’ve seen regularly. Yeah, no. I think it’s safe to say that if I’ve opted out from receiving your mail, you should probably put my data away in a dark closet and not touch it again. But.. but.. but… But nothing. Go away. As for the lack of an unsubscribe link, get over yourself. You’re not that special. I don’t think that this really is something that counts for exemption.
Also, is there an official template? So many of these emails look identical. I have to give credit to whomever did it first. Because if plagiarism is the sincerest form of praise, you have an entire industry praising you.
Finally, it’s been amusing to watch the general frustration with all the GDPR mail. It seems many people are getting tired of the deluge. That’s OK, though, it should end by Saturday. Or so we can only hope.

OATH and Microsoft updates

I’ve seen multiple people asking questions about what’s going to happen with the Yahoo and AOL FBLs after the transition to the new Oath infrastructure. The most current information we have says that the AOL FBL (IP based) is going away. This FBL is handled by the AOL infrastructure. As AOL users are moved to the new infrastructure any complaints based on their actions will come through the Yahoo complaint feedback loop (CFL). The Yahoo CFL is domain based. Anyone who has not signed up for the Yahoo CFL should do so.
When registering you will need each domain and the selectors you’re planning on using. Yahoo will send an email with a confirmation link that needs to be clicked on within a short period of time in order to activate the FBL.
Microsoft’s SNDS program had an outage at the end of last week. That’s been fixed, but the missing data will not be back populated into the system. This has happened a couple times in the past. It seems the system gets a live feed of data. If, for some reason, the data is interrupted, then it’s gone and doesn’t get populated.

Why is my cold email going to the spam folder?

Because that’s what the spam folder is for unsolicited email.

A little housekeeping

I’ve been blogging regularly for over a decade now, and for much of that time I’ve posted 5 days a week. For a lot of reasons I’m finding that schedule harder and harder to keep up with. Part of it is that this spring I took on more, and bigger, clients than I have in the past. This means a larger portion of my time is scheduled and committed than in the past. I also find myself wanting to write about bigger, more complex issues; stuff that takes longer than the 45 minutes – 2 hours I regularly spend on blog posts.
The last few months, I’ve been considering what to do about blogging. I could simply cut back the amount I write here. Except that regularly blogging forces me to think about what’s going on in the broader industry, and that’s important to me and I think makes me a better consultant. I could write a few short posts a week, and a bigger meatier post once or twice a month, but I’ve been me long enough to know that’s not the best solution. I could just keep going as I have been most of this year and just post when I have something to say and not worry about frequency.
I still don’t have the answer. Of course, there’s not a right answer, there’s just a move forward and do what works. I have a lot of travel coming up next month (including speaking at Activate: The ActiveCampaign Conference) so things might get wonky for a while. But, I’m not planning on giving up blogging.
One of the consequences of my time constraints is that I have handed comment moderation off to other folks. Comments might sit for longer than they used to before approval. They’re being processed, just a little more slowly than they have in the past. I don’t think it’s a big deal, it’s not like there’s a significant horde of commenters here. When I was moderating comments basically anything that contributed to the discussion and didn’t come from a forged email address was approved. The current policy is similar.
I am around on the email geeks slack channel, and am often talking about stuff on the deliverability channel.
Thus ends the housekeeping.

Want some history?

I was doing some research today for an article I’m working on. The research led me to a San Francisco Law Review article from 2001 written by David E. Sorkin. Technical and Legal Approaches to Unsolicited Electronic Mail (.pdf link). The text itself is a little outdated, although not as much as I expected. There’s quite a good discussion of various ways to control spam, most of which are still true and even relevant.

From a historical perspective, the footnotes are the real meat of the document. Professor Sorkin discusses many different cases that together establish the rights of ISPs to filter mail, some of which I wasn’t aware of. He also includes links to then-current news articles about filtering and spam. He also mentions different websites and articles written by colleagues and friends from ‘back in the day’ discussing spam on a more theoretical level.
CNET articles on spam and filtering was heavily referenced by Professor Sorkin. One describes the first Yahoo spam folder. Some things never change, such as Yahoo representatives refusing to discuss how their system works. There were other articles discussing Hotmail deploying the MAPS RBL (now a part of Trend Micro) and then adding additional filters into the mix a few weeks later.
We were all a little naive back then. We thought the volumes of email and spam were out of control. One article investigated the effectiveness of filters at Yahoo and Hotmail, and quoted a user who said the filters were working well.

EFAIL PGP / S/MIME "flaw" ?

There’s going to be a lot of hype today about something the security researchers who found it are calling “EFAIL”. Interviews, commemorative T-Shirts, press tours, hype.
The technical details are interesting, but the un-hyped end-user advice would probably be “If you’re using a mail client that’s got bugs in it’s MIME handling, and you’ve configured it to load remote content automatically, and you’re using a less secure encryption tool or protocol, and you’ve configured it to decrypt things automatically, and security of your email is so important to you that you’re defending against skilled attackers who have already acquired the encrypted emails you’re concerned about (by compromising your ISP? Sniffing non-TLS traffic?) then you may have a problem.”
I can’t imagine anyone for whom email security is a critical issue would make all those mistakes, so this mostly merits a heads-up to the MUA developers (which has happened) and maybe a “Do people rely on S/MIME? Why?” retrospective. But as someone on twitter described it “The Vulnerability Hype Train has begin, choo choo.”

There are several different issues all mixed together by the efail folks. All of them require an attacker to already have access to (encrypted) sensitive emails, and to send copies of those to you wrapped up in another message and to have you decrypt that incoming mail.