Is open source software more vulnerable to malicious attacks than proprietary software?

The open source nature of an o/s provides a superior vehicle to making security vulnerabilities easier to spot and fix, not only because more people can look at it, but more importantly, because the model forces people to write more clear code, and to adhere to standards. This in turn facilitates security reviews and solves the issue on a core level. Open source software projects can be more secure than closed source projects. However, the very things that can make open source programs secure such as the availability of the source code, and the fact that large numbers of users are available to look for and fix security holes and exploits can also lull people into a false sense of security. Security consciousness is really up to the end user.