That’s what a survey of 350 IT and network professionals would indicate, with large companies in particular reporting this to be worse than last in terms of suffering at least one network intrusion of their user machines, office network or servers. The Sixth Annual Enterprise IT Security Survey, released Monday, found that 67% of large companies with 5,000 or more employees reported one successful intrusion or more this year, compared with 41% in 2009. For the first time, the survey, sponsored by VanDyke Software and undertaken by Amplitude Research in mid-September, delved into what the survey respondents believed primarily caused the network intrusion.