The biggest proportion of attacks on Linux systems come from authorised users and most were enabled by security misconfigurations, according to a new survey of Linux developers from Evans Data.

Linux developers said they had few problems with attacks and viruses overall, with 92 percent saying their Linux systems have never been infected with a virus, and 78 percent saying their systems have never been hacked. Less than seven percent claimed to have been hacked three or more times.

Two years ago, 94 percent were virus-free, while the attack figures were about the same. Despite the slight fall, however, the figures remain far below the average. In a survey of all types of North American developers this spring, Evans found that 60 percent of developers said they had been breached and 32 percent had been hit at least three times.

While the responses of Linux developers on such a controversial issue are not necessarily reliable, they are reinforced by a general perception amongst developers, of all stripes, that Linux is the most secure platform. In a survey of more than 400 developers and IT managers last month, the largest proportion of respondents - 25 percent - said Linux was the most secure platform, followed closely by Windows 2003 at 19 percent.

Windows 2003's position has jumped more than 40 percent in the past six months, Evans said, boosted by the platform's explicit security support. Windows XP, and Trusted Solaris were chosen by less than 10 percent, while Mac OS X, IBM's AIX, HP-Unix, Windows NT and other operating systems were named by less than 5 percent.

Of the 22 percent of admitted hacks, the largest proportion - 23 percent - were by internal users with valid login IDs, respondents said. The top factor allowing the attack was misconfiguration, at 13 percent, followed by Internet service vulnerabilities (8.2 percent) and Web server flaws (8.0 percent). Linux kernel flaws allowed 5.5 percent of the attacks, Evans said. Examples of misconfiguration include forgetting to put a server behind a firewall and improperly enabling the firewall.

"Ironically, the flaws that crackers use to compromise Linux servers are flaws in applications which run on competing operating systems, so those vulnerabilities are not specific to Linux," said Nicholas Petreley, Evans Data's Linux analyst, in a statement.

Linux developers aren't alone in blaming users for allowing security breaches. In last month's security survey, Evans found that the biggest proportion of developers, one in four, said the biggest problem in implementing security was "social engineering", that is, users' lack of adherence to security policies. Fifteen percent said their biggest headache was a lack of qualified personnel. They had little sympathy for user incompetence, with only 11 percent agreeing that security systems were too complicated.

Developers also disagreed with the oft-cited user complaint that security gets in the way of performance, with only 1.3 percent citing performance as a difficulty.

Adoption of the new version 2.6 Linux kernel is proceeding apace, rising more than 80 percent in the past six months, Evans said. Two in five developers have now migrated at least some of their Linux installations to the 2.6 kernel, with more than 30 percent planning the switch within six months, and 12 percent expecting migration to take longer than one year.

"Only recently have major Linux distributors started including the 2.6 kernels as the default, so at least some portion of the large number of developers represented here as using a 2.6 kernel are likely to have installed it manually, themselves," Evans Data said in the report.