These companies have a lot of data, there are easy ways in and the intrusions can take a very long time to detect.
The second-most commonly hacked industry was financial services. However, this industry was far more likely to have commissioned a pre-breach audit. TrustWave says this is a sign that the industry is taking cyber-security more seriously.
As we reported on our IT Business Edge site, the TrustWave report also found that companies are so busy chasing down the latest vulnerabilities that they are overlooking the most common, frequently exploited ones.