The most significant growth was reported for drive-by attacks in which e-mails link to manipulated Web sites that infect the users’ computers when opened in a browser.
Between August and September 2012, the number of such attacks increased more than 80-fold and their share of overall spam levels increased from 0.1% to 9.5%.
However, that growth was not at the expense of “classic” malware e-mail, which contains malware as an attachment: the number of malware e-mails increased by 119% in September and by 252.8% as compared to the same month in 2011.
Virus outbreaks remained roughly at the previous month’s level (–5.7%), but increased by 50.5% in August. The plus was 186.4% as compared to September 2011.
Following strong growth in June and July, spam levels reduced somewhat in August and September: although levels remained at July’s high level in August (–1.4%), those levels declined by 36.5% in September. There was an absence of several major spam waves, especially in the second half of September, and which were responsible for the drop. Despite the decline, spam levels still remained above the values of the first five months of the year.
The main cause for the decline in spam was the absence of major spam waves from Saudi Arabia, which had significantly contributed to the spam growth in June and July.
In September, Saudi Arabia only came in seventh in the ranking of countries of spam origin with 5.3% of all spam e-mails; in August, the country had still been in first place with a record share of 28.9%. India once again came in first with 16.4%, followed by Turkey (5.8%) and Spain, which jumped from twelfth in August to third (5.6%). The US, the long-term spam leader, came in fifth with 4.3%.
One noticeable change in September was a wider distribution in spamming: while the five largest spam countries of origin were still responsible for significantly more than half of all spam emails in August (59.9%), that share fell to slightly more than one third in September (38.7%). In September, the share of top-ten spamming countries was even slightly below the top five in August with 59.3%.
Shifts also occurred in September in terms of spam topics: one noticeable trend was a dramatic increase in the share of particularly dangerous e-mails. Drive-by mailings came in third in the category of spam topics with 9.5%; fraudulent scam e-mails increased from 0.2% to 2.1%. Advertisements for pharmaceutical products remained the most important spam topic, but their share decreased from 56.3% to 46.9%.
On an international scale, well-known and popular brands were used as a pretense for malware dissemination and drive-by attacks. In addition to social media platforms such as LinkedIn and Facebook, that also included Microsoft as well as the US consumer protection organization Better Business Bureau.
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