How can i prevent from a bad plugins ?

first off If you have a good virus protection program you should be able to scan the file in question. If it has malware or a virus on it, the program should pick it up. If you saw Yahoo yesterday Microsoft is giving a free anti virus /malware program for nothing absolutely free called Total AV. Download it and then run it to scan your computer. After it is done run the malware program on that word press file. if there is any malware on it. Total AV should pick it up. That is my best suggestion to you ...Norman

The official plugin repository has tens of thousands of free plugins to extend your website. These plugins are not guaranteed to be big-free but plugins that introduce security vulnerabilities are removed quickly. Plus, the repository has a rating system where users can rate the plugins and give additional information and feedback. Support is often available for these plugins as well, directly through the repository. My advice is to look first in this repository for possible solutions and be sure to check the rating and read some reviews. Another place to find quality plugins is Code Canyon. Thousands of other plugins are available for free or paid as well.