Vehicular ad hoc networks (VANETs) have become one of the most promising and fastest growing subsets of mobile ad hoc networks (MANETs). They are comprised of smart vehicles and roadside units (RSU) which communicate through unreliable wireless media. By their very nature, they are very susceptible to attacks which may result in life-endangering situations. Due to the potential for serious consequences, it is vital to develop security mechanisms in order to detect such attacks against VANETs. This paper aims to survey such possible attacks and the corresponding detection mechanisms that are proposed in the literature. The attacks are classified and explained along with their effects, and the solutions are presented together with their advantages and disadvantages. An evaluation and summary table which provides a holistic view of the solutions surveyed is also presented.