India and Brazil remained the most popular sources of spam in April, accounting for 12.76 per cent and 7.15 per cent of the total volume of spam respectively, Kaspersky Lab has announced in its spam report for April 2011.
Compared to the previous month the amount of spam in email traffic increased by 1.2 percentage points and averaged 80.8 per cent.
In the second half of April, the average figure exceeded 83.6 per cent, suggesting the share of unsolicited mail will continue to grow in the coming month.
Russia continued its slide down the rating of most popular spam sources, being overtaken by South Korea whose contribution to global spam almost doubled compared with March's figure.
Of particular interest in April was the appearance of Packed.Win32.Katusha.n and Trojan-Downloader.
Win32.FraudLoad.hxv in the rating of malicious programs blocked by mail antivirus.
Both malicious programmes are linked to fake AV: the former is used to pack them while the latter downloads them to users' computers.
In April, malicious files were found in 3.65 per cent of all emails, an increase of 0.43 percentage points compared with the previous month.
USA, Russia and UK continued to occupy the top three places in the list of countries where malware was detected most frequently in mail traffic.
There was an increase of 1.93 percentage points recorded in the USA, but the figure for Russia decreased by 2.9 percentage points compared to March.
According to the report, in April, phishers seemed to lose interest in eBay with almost half as many of its users being attacked compared to the previous month.
The subsequent drop of 4.2 percentage points saw eBay fall two places to 4th in the Top 10 rating of organisations most often targeted in phishing attacks.
PayPal was the undisputed leader of April's rating.
However, the intensity of the attacks on this e-pay system has eased off slightly, with a drop of 6 percentage points compared to March.
Facebook and Santander moved up to 2nd and 3rd respectively, though the number of attacks on these organisations only increased slightly compared with March.