Distributed Denial of Service attacks (DDoS) are one of the biggest problems facing the Internet. To eliminate this type of attack, the number of which has increased in the period under study, various methods of defense have been proposed. However a detection mechanism that is able to completely counteract the attacks has not yet been found. Therefore, detection and defense against DDoS attacks is of great importance for specialists engaged in computer security. This paper presents a systematic review of the scientific literature on methods of detecting DDoS attacks. From the literature the main aspects related to detection have been formulated. Six aspects for analysis in this investigation were identified: techniques, variables, tools, deployment location, point in time and detection accuracy. It was found that each technique used for the detection of attacks exploits certain characteristics of the network traffic, user requests and specific tools. Finally, it managed to identify the mechanisms that have the highest detection accuracy, such as the datasets they use. It has been concluded that an adequate analysis of the above aspects of detection of DDoS attacks can make a useful contribution to designing an appropriate strategy for neutralizing the attacks.