[Background:] Research on automated requirements elicitation and analysis of mobile apps employed lots of techniques and tools proposed by RE researchers and practitioners. However, little is known about the characteristics of these techniques and tools as well as the RE tasks in requirements elicitation and analysis that got supported with the help of respective techniques and tools. [Aims:] The goal of this paper is to investigate the state-of-the-art of the techniques and tools used in automated requirements elicitation and analysis of mobile apps. [Method:] We carried out a systematic mapping study by following the guidelines of Kitchenham et al. [Results:] Based on 73 selected papers, we found the most frequently used techniques - semi-automatic techniques, and the main characteristics of the tools - open-sourced and non-self-developed tools for requirements analysis and text pre-processing. Plus, the most three investigated RE tasks are requirements analysis, mining and classification. [Conclusions:] Our most important conclusions are: (1) there is a growth in the use of techniques and tools in automated requirements elicitation and analysis of mobile apps, (2) semi-automatic techniques are mainly used in the publications on this research topic, (3) requirements analysis, mining and classification are the top three RE tasks with the support of automatic techniques and tools, and (4) the most popular tools are open-sourced and non-self-developed, and they are mainly used in requirements analysis and text processing.