USA, your poorly protected PCs are polluting the world with spam

Filed Under: Malware, Spam

World spam
Latest estimates reported in the press suggest that more than 2.2 million PCs based in the USA were hijacked by cybercriminals in the first half of 2010, and used as part of a botnet.

And what's one of the principal reasons why cybercriminals compromise innocent users' PCs? To send spam without their knowledge.

It's still a surprise to many people who don't work in the field of computer security, but the vast majority of the spam you receive in your inbox is not sent from the spammers' own computers but relayed through infected PCs belonging to regular members of the public.

In other words, Aunty Hilda could be the one pumping out all that Viagra spam.

And where are most of the world's Aunty Hildas? The United States.

Here are the latest stats from SophosLabs, showing the "dirty dozen" spam-relaying countries for the third quarter of this year.

The top twelve spam relaying countries for July - September 2010

1. USA 18.6%
2. India 7.6%
3. Brazil 5.7%
4. France 5.4%
5. UK 5.0%
6. Germany 3.4%
7= Russia 3.0%
7= S Korea 3.0%
9. Vietnam 2.9%
10. Italy 2.8%
11. Romania 2.3%
12. Spain 1.8%
Other 38.5%

Top spam-relaying continents, July - September 2010

1. Europe 33.1%
2. Asia 30.0%
3. N America 22.3%
4. S America 11.5%
5. Africa 2.3%
Other 0.8%

You should never even be tempted to open a spam message out of curiosity, as it can only take a second to effectively hand over control of your computer to the spammers. If your computer does become part of a botnet, you're also inviting further malware infections, which may compromise your personal or banking details.

The best way for users and administrators to reduce the risk of being compromised is to run anti-spam and anti-malware protection, behave sensibly when online, and ensure systems are up-to-date with security patches.

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One Response to USA, your poorly protected PCs are polluting the world with spam

  1. Ian W · 1674 days ago

    As there are only seven continents, and Antarctica is unlikely to making a major contribution just yet, can we conclude that Other = Australasia?


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About the author

Graham Cluley runs his own award-winning computer security blog at, and is a veteran of the anti-virus industry having worked for a number of security companies since the early 1990s. Now an independent security analyst, he regularly makes media appearances and gives computer security presentations. Follow him on Twitter at @gcluley