Email is inherently a malicious traffic stream

It’s something many people don’t think about, but the majority of the traffic coming into the SMTP port is malicious. Spam is passively malicious, in that it just uses resources and bothers people. But there is a lot of actively malicious traffic coming into the SMTP port. Email is used as a vector to spread viruses and other malware. Email is also used for phishing and scamming. Many of the major hacks we’ve heard about over the last few years, including those in the email space, started with a single user getting infected through email.
We talk a lot about delivery here with clients and primarily focus on making sure their mail looks as unlike malicious mail as possible. We focus on spam filters, but every piece of mail goes through filters that also look for viruses, phishes, malware and other malicious traffic.
Mail servers are under attack constantly. The only reason our inboxes are useful is through the hard work of many people to filter out the bad and keep users from seeing the bulk of the mess attacking them.

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SWAKS: the SMTP Swiss Army Knife

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SWAKS is a general purpose testing tool for SMTP. For basic SMTP testing it’s a more convenient, scriptable alternative to running a transaction by hand, but it also lets you test things that are difficult to do manually, such as authentication or TLS encryption.
It’s a perl script that installs fairly easily on OS X or any Linux/unix system (and can be installed on Windows, if you have perl installed there).
It’s pretty well documented, but it can be a bit overwhelming to start with. Here are some simple recipes:
Send a test email:

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DNS Changer servers going offline

There are a whole host of different botnets. One botnet run by Rove Digital infected computers with viruses that changed their DNS settings, giving the botnet runners the ability to control how the infected computers viewed the Internet.
The criminals behind the DNS Changer virus were arrested in November of last year. The court ordered the Internet Systems Consortium (ISC) to operate replacement DNS servers for computers infected with the botnet viruses in order to give users a chance to clean and fix their computers.
That court order expires on Monday.
Anyone who is still infected with the DNS Changer malware will see their internet services greatly curtailed when the DNS servers go offline.
If you run Windows and you haven’t yet checked to see if you’re infected, you should do so soon. There are a number of websites you can visit that will tell you if you are actually infected with the DNS changer virus and if you are will give you information on how to fix your system.

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Spam, Phish or Malware?

Some mornings I check mail from my phone. This showed up this morning.
PizzaHutMail
My first thought was “oh, no, Pizza Hut is spamming, wonder who sold them my address.”
Then I remembered that iOS is horrible and won’t show you anything other than the Friendly From and maybe it was some weird phishing scheme.
When I got to my real mail client I checked headers, and sure enough, it wasn’t really from Pizza Hut. I’m guessing actually malware, but I don’t have a forensics machine to click the link and I’m not doing it on anything I can’t wipe (and have isolated from the rest of my network).
The frustrating thing for me is that this is an authenticated email. It not from Pizza Hut, the address belongs to some company in France. Apparently, that company has had their systems cracked and malware sent through them. Fully authenticated malware, pretending to be Pizza Hut, and passing authentication on various devices.
Pizza Hut isn’t currently publishing a DMARC record, but in this case, a DMARC record for Pizza Hut wouldn’t matter. None of the email addresses in the headers point to Pizza Hut.
I spent last week listening to a lot of people discussing DMARC and authentication and protecting people from scams and headers. But those all the protocols in the world won’t protect against this kind of thing. Phishing and malware can’t be fixed by technology alone. Even if every domain on the planet published a p=reject policy, mail like this would still get through.
 
 
 

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