Sophos, the veteran IT security vendor, says that the US retains its spam king position, despite the fact that the criminal fraternity are tapping into malware spreading, phishing emails and social networking attacks as a replacement for traditional spam characteristics.
The 'dirty dozen' Q4 report shows that the US has actually increased its lead at the top spot, and continues to be responsible for nearly one in five junk emails: 18.83% of all spam messages.
According to Sophos, the domination by the US underlines the continuing problem of computers being compromised by hackers in the country, allowing them to be remotely controlled for criminal purposes without the owners' knowledge.
The UK decreased its percentage of total spam output compared to the third quarter last year – from 5% to 4.54% – although the report notes it remains in fifth position overall.
The report warns that there has also been an increase in more focused, targeted email attacks, known as spearphishing.
In parallel with this, Sophos says it is continuing to receive an increased number of reports of malicious apps, compromised profiles and unwanted messages spreading across social networks such as Facebook and Twitter.
"Spam is certainly here to stay, however the motivations and the methods are continuing to change in order to reap the greatest rewards for the spammers", said Graham Cluley, Sophos' senior technology consultant.
"What's becoming even more prevalent is the mailing of links to poisoned webpages - victims are tricked into clicking a link in an email, and then led to a site that attacks their computer with exploits or attempts to implant fake anti-virus software", he added.
In his security blog, Cluley went on to say that many people haven't learnt is that the spammers don't use their own computers to send spam, instead they create botnets of compromised PCs around the world.
They use these, he explained, to remotely spew out unwanted marketing messages, malicious links and even launch distributed denial-of-service attacks.
"It appears that some of the botnets used to send a lot of the spam (Rustock is the most notable one) may have stopped pumping out unwanted messages in the last few weeks", he said.
"That doesn't mean that computer users have cleaned-up their home computers, but rather that the bad guys are now using the botnet for other activities. For instance, installing revenue-generating pop-up adverts or identity theft from unsuspecting home users", he added.