Monthly Archives: March 2012

Did snowshoe spamming cause the big February spam surge?

It turns out the source of the big spam surge that rocketed eight ASNs

1 (9) AS 21788 NOC
2 (-) AS 27229 WEBHOST-ASN1
4 (-) AS 33055 BCC-65-182-96-0-PHX
6 (5) AS 15149 EZZI-101-BGP
7 (-) AS 13768 PEER1
8 (-) AS 10439 CARINET
9 (-) AS 7796 ATMLINK
to the top of the U.S. February 2012 was not a botnet: it was apparently snowshoe spamming. Here are the most-affected eight U.S. ASNs again, with their rankings for February, listed in the table on the right.

So, Ogee is not a botnet; it is a collection of IP addresses apparently involved in snowshoe spam. It’s also not new. Ogee is just a specific set of snowshoe addresses. But what is snowshoe spam?

Paul Roberts wrote for ThreatPost 6 October 2011, Expert: Eight Years Later, ‘Snowshoe Spam’ Suggests CAN SPAM Not Working,

Brett Cove, a researcher for anti malware firm Sophos, told attendees at the annual Virus Bulletin Conference on Thursday that so-called “snowshoe spam” is becoming a bigger problem, even as spam e-mail volumes associated with botnets are receding. Snowshoe spam is responsible for the bulk of spam messages that make it past anti spam filters at U.S. firms, even as bulk senders avoid prosecution by adhering to the letter of the U.S. CAN SPAM anti-spamming law.

Snowshoe spam isn’t a new problem. In fact, within anti spam circles, researchers have been talking about the phenomenon for years. The term “snowshoe” spam comes from the tactic of spreading the load of spam runs across a wide range of IP addresses as a way to avoid detection by anti spam filters, in the same way that snowshoes spread the weight of their wearer across a wide area to avoid breaking through snow and ice.

Anti spam filters are typically programmed to allow only a small volume of identical e-mail messages from the same IP address range, Cove told Threatpost. Snowshoe spam is able to avoid—or postpone—the filters by sending mail from a range of addresses, often leased by the bulk mail senders, he said.

That may sound a lot like low-and-slow botnet spamming, but there are five key differences:

Continue reading

What other ASNs were affected by botnet Ogee in February 2012?

Previously we determined that nine ASNs that showed spam surges in the U.S. and Canadian top 10 for February 2012 were infested by the botnet Ogee and that spam came from that botnet. What other ASNs were affected by Ogee in the same time period?

Let’s look at the top 10 ASNs infested by Ogee according to spam volume for 1 Feb 2012 to 12 Mar 2012:

Left Axis: Total Ogee volume (spam messages);
Right Axis: top 10 Ogee ASN volume (dotted curves)

It looks like Ogee is a new botnet, since all these top 10 ASNs came up from zero volume before 18 February 2012. The biggest initial peak in this graph is from AS 21788 NOC, #1 in the U.S. February top 10, and the biggest late surge is from AS 10439 CARINET, #8 in that same ranking. Right below CARINET is AS 32613 IWEB-AS, Canadian February #1. The rest of the 8 Ogee-infested from the U.S. top 10 previously described also are in there, except AS 7796 ATMLINK and AS 13768 PEER1.

New here are these three: Continue reading

Did the February 2012 spam surge come from one botnet? saw
AS 21788NOC
AS 33055BCC-65-182-96-0-PHX
AS 15149EZZI-101-BGP
AS 13768PEER1
a huge surge in spam from some U.S. ASNs, mostly from ones that hadn’t even been in the top 10 before, with possible correlations in one ASN each from Peru and Canada. Did all this spam come from the same botnet?

Maybe not all, but most. Eight out of the U.S. top 10 for February show very close correlation with one botnet, Ogee. They are listed in the table on the right and shown in the chart below:

Left Axis: ASN volume (spam messages); Right Axis: Botnet volume (dotted curves)

The chart also shows some ASNs reacted quickly and stopped the spamming, while others got worse. It’s a busy chart, so let’s look at simpler charts for one example each of resilient and susceptible ASNs.

AS 21788 NOC was one of the first and worst affected by this spam surge: Continue reading

Big U.S. Spam Spike in February 2012

What could push the U.S. from 13 to 2 in worldwide, and way up to number one for the last week of February 2012?

In the U.S. rankings by ASN, seven out of ten are new, and NOC number 1 came up from number 9. Something pretty bad is going on. So bad Comcast didn’t place in the top 10 at all, for the first time in recent memory!

NOC has had this problem before, in July and November 2011, but never with this amount of spam volume. And this time many other ASNs show the same pattern.

The same issue may be in the Canadian rankings as well: AS 32613 IWEB-AS jumped from 8 to 1 for the month, with almost all the increase in the same last week of the month as for the U.S. problem ASNs.

There was even a similar curve in the World rankings, for Telefonica del Peru’s AS 6147 SAA.

Our next step is to drill down to see if these ASNs were infected by the same botnet. We did that for the medical ASNs last month, but this is a much bigger spam event this month.