Unfortunately, the benefit of having a system of open code exchange also comes along with certain drawbacks. In a recent report by McAfee, they are warning that criminals and digital mischief makers are using code-sharing more and more frequently as a way to further develop viruses and other malicious software.

After all, a bad program has a better chance of succeeding if five minds can collaborate over how to best exploit a new vulnerability. McAfee speaks of close-knit groups that work together often, and nasty software development being virtually parallel to traditional software:

However, these groups are much harder to join than open-source software communities, as the malicious software writers try hard not to attract the attention of the authorities. McAfee said that malicious software now has a long-term development cycle, with code being developed, bugs being fixed, and betas and final versions being distributed among the malicious software community in ways similar to those used in legitimate open-source communities.
While some may see this as justification to move to or stick with closed-source, proprietary development, the real answer to this is most likely just the opposite. Collaboration among security professionals and program developers is the best long-term solution, to both create software that is relatively bug-free but also quick to fix when flaws are discovered. After all, if the hackers are teaming up against you, your best bet is to find friends of your own.