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Amazon EC2’s spam and malware problems

Over the past few weeks, I’ve increasingly heard of spam and abuse problems originating in Amazon EC2.

This has culminated in a blog post yesterday by Brian Krebs at the Washington Post:

It took me by surprise this weekend to discover that that mounds of porn spam and junk e-mail laced with computer viruses are actively being blasted from digital real estate leased to [Amazon].

He goes on to discuss how EC2 space is now actively blocked by Outblaze, and has been listed by Spamhaus in their PBL list. A spokesperson for Amazon said:

“We have a clear acceptable use policy and whenever we have received a complaint of spam or malware coming through Amazon EC2, we have moved swiftly to strictly enforce the use policy by network isolating (or even terminating) any offending instances,” Kinton said. She added that Amazon has since taken action against the EC2 systems hosting the [malware].

However as Seth Breidbart noted in the comments, ‘note that Amazon will terminate the instance. That means that the spammer just creates another instance, which gets a new IP address, and continues spamming.’ True enough — as described, instance termination simply isn’t good enough.

My recommendations:

  • as John Levine noted, it’s likely that Amazon need to treat EC2-originated traffic similarly to how an ISP treats their DSL pools — filtering outbound traffic for nastiness, in particular rate-limiting port 25/tcp connections on a per-customer basis, so that an instance run by (or infiltrated by) a spammer cannot produce massive quantities of spam before it is detected and cut off.

    However, I’m not talking about blocking port 25/tcp outbound entirely. That’s not appropriate — an EC2 instance is analogous to a leased colo box in a server farm, and not being able to send mail from our instances would really suck for EC2 users (like myself and my employers).

  • It would help if there were a way to look up customer IDs from the IP address of the EC2 nodes they’re using — either via WHOIS or through rDNS. Even an opaque customer ID string would allow anti-abuse teams to correlate a single customer’s activity as they cycle through EC2 instances. This would allow those teams to deal with the reputation of Amazon’s customers, instead of Amazon’s own rep, analogous to how “traditional” hosters use SWIP to publicize their reassignments of IPs between their customers.

There’s some more discussion buried in a load of knee-jerking on the NANOG thread. Here’s a few good snippets:

Jon Lewis: ‘I got the impression the only thing Amazon considers abuse is use of their servers and not paying the bill. If you’re a paying customer, you can do whatever you like.’ (ouch.)

Ken Simpson: ‘IMHO, Amazon will eventually be forced to bifurcate their EC2 IP space into a section that is for “newbies” and a section for established customers. The newbie space will be widely black-listed, but will also have a lower rate of abuse complaint enforcement. The only scalable way to deal with a system like EC2 is to provide clear demarcations of where the crap is likely to originate from.’

Bill Herrin: ‘From an address-reputation perspective EC2 is no different than, say, China. Connections from China start life much closer to my filtering threshold that connections from Europe because a far lower percentage of the connections from China are legitimate. EC2 will get the same treatment.’

There’s also an earlier thread here.

Anyway, this issue is on fire — Amazon need to get the finger out and deal with it quickly and effectively, before EC2 does start to run into widespread blocks. I’m already planning migration of our mail-sending components off of EC2; we’re already seeing blocks of mail sent from it, and it’s looking likely that these will increase. :(

(It’s worth noting that a block of EC2’s netblocks today will produce a load of false positives, mainly on transactional mail, if you’re contemplating it. So I wouldn’t recommend it. But a lot of sites are willing to accept a few FPs, it seems.)