Named Data Networking (NDN), one of the most suitable candidates for the future Internet architecture, allows all network nodes to have a local cache that is used to serve incoming content requests. Content caching is an essential component in NDN: content is cached in routers and used for future requests in order to reduce bandwidth consumption and improve data delivery speed. Moreover, NDN introduces new self-certifying contents features that obviously improve data security and make NDN a secured-by-design architecture able to support an efficient and secure content distribution at a global scale. However, basic NDN security mechanisms, such as signatures and encryption, are not sufficient to ensure security in these networks. Indeed, the availability of the Data in several caches in the network allows malicious nodes to perform attacks that are relatively easy to implement and very effective. Such attacks include Cache Pollution Attacks (CPA), Cache Privacy Attacks, Content Poisoning Attacks and Interest Flooding Attacks. In this paper, we identify the different attack models that can disrupt the NDN operation. We conducted several simulations on NDNSim to assess the impact of the Cache Pollution Attack on the performance of a Named Data Network. More precisely, we implemented different attack scenarios and analyzed their impact in terms of cache hit ratio, data retrieval delay and hit damage ratio.