Security tools have found 16 million pieces of malicious
software on Windows computers over the past 15 months, research
released by Microsoft has revealed.
The report on malware found on 5.7 million machines is based on
the data collected by Microsoft’s Windows Malicious Software
Removal Tool, which was first launched in January 2005.
It shows the tool has been used approximately 2.7 billion times
on at least 270 million computers. It has removed at least one
malware item from every 311 computers it runs on.
Backdoor Trojans, which allow attackers to control infected
computers and steal confidential information, are “a significant
and tangible threat to Windows users”, the research says. Backdoor
Trojan’s were present on 62% of the computers infected with
malware, with bots making up the majority.
Rootkits, which make system changes to hide other possibly
malicious components, were “a potential emerging threat but have
not yet reached widespread prevalence”, the report says, with
rootkits found on 14% of infected machines. But this figure drops
to 8% if WinNT/F4IRootkit, the controversial rootkit distributed on
Sony music CDs as an anti-copying measure, is excluded.
Worms spread through email, peer-to-peer networks and instant
messaging had hit 35% of the infected machines.
The forthcoming Windows Vista is set to include beefed up
security systems, but analysts warned last month that users may be
annoyed by the intrusive and repetitive effect of the new
features.