Once again, the subject is spam.
Depending on the “stars” and the time of year, the proportion of spam can range from anywhere between 70 and 90% of all email traffic.
Sounds like a lot, eh? But when you take all Internet traffic into consideration, it’s not actually that much – email traffic accounts for around just 1%. On the other hand, you can’t just forget about spam. Here is a bit more about spam’s role in the cybercrime ecosystem. Combating this particular evil is part of the massive war we are waging on cybercriminals. It’s no exaggeration to say that if we fail on this front, the rest of our efforts will amount to nothing.
In other words, we love anti-spam technologies and promote them as much as possible. There is, however, a subtle difference from anti-malware technologies. More precisely, there are different criteria for evaluating the quality of protection for anti-spam and anti-malware technologies. For malware it’s fairly easy: the higher the detection level, the better. For spam it’s more important to have no false positives. This is quite reasonable: it’s much better for the user to take a couple of seconds to delete a spam message that sneaks through the filter than miss important business correspondence. So, protection against spam is, in a way, a more complicated task, literally trying to kill two birds with one stone. In this difficult task, cloud technologies are a great help.
As I wrote earlier, we’ve been using cloud technologies for a while, and with considerable success. But one interesting detail has amazingly been overlooked, and unfairly so. In the cloud-based Kaspersky Security Network (KSN), (video, details) there’s a rather impressive anti-spam cloud. It started from the Urgent Detection System (UDS). The link to similar anti-malware technology is no coincidence: both are based on similar principles.
This is how the traditional anti-spam technology works.
Let’s say an email arrives at a computer. It is immediately assailed by various anti-spam technologies, both local and cloud-based, which test the message and give verdicts. Based on these, the system decides whether this message lives or dies.
And this is what happens in the UDS.
The system takes a micro-signature from the email message and sends it to the cloud to check it against a dedicated spam database. Earlier we used 16-byte hashes; in 2011 we started the UDS2 (UDS 2nd generation) procedure involving 4-byte fuzzy hashes, which are more effective against obfuscated texts and are therefore better at filtering out spam. Importantly, these hashes do not create extra work for the analyst, since the system creates them automatically based on collected spam samples.
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