Trojans accounted for 70 percent of all new malware between April and June 2009, according to a second quarter report from PandaLabs.

The report found a 6.25 percent drop in spyware, which now accounts for just 6.9 percent of all new malware. In contrast, adware rose significantly over this period, from 7.54 percent in the previous quarter to 16.37 percent. The increase is largely due to fake antivirus applications. The percentage of worms also rose slightly, now accounting for 4.4 percent of all malware.

Trojans were also responsible for more infections than any other type of malware during the quarter. This type of malware was behind 34.37 percent of all infections detected by PandaLabs, an increase of 2.86 percent over the previous quarter.

A worm appeared in April which used a cross-site scripting technique to infect Twitter users when they visited the profiles of other infected users. It then infected the new users’ profile to continue spreading.

In early June, Twitter was the focus of other attacks, this time using different techniques, mostly BlackHat SEO. Twitters’s “Trending Topics” were targeted by malicious users writing tweets about the topics listed in Twitter Trends with links to malicious web pages from which malware was downloaded.

The first attack focused on just one of the topics, but a few days later the scope of the attack increased and all popular topics contained malicious links.