# The Digital Footprints on the Run: A Forensic Examination of Android Running Workout Applications
## 1 Introduction
In 2015, the police used GPS coordinates and step pace, which were stored in a Garmin smartwatch, to help bring charges to a man for a double homicide, correlating the time/date of the homicides with the coordinates stored in the smartwatch to draw the suspect's escape route [6]. Another publicly known case is the use of Strava in running mode to identify and convict a man of hitting and injuring a cyclist in Virginia, USA [7]. A final example is a case where the fitness application Apple Health data were used to convict a man of rape and murder: the police apprehended the man's iPhone, extracted the data and correlated them with the time and location of the murder [8]. Therefore, fitness applications can provide valuable data in digital forensics as they store a wealth of private information related to the user in specific companion applications such as Garmin Connect [9]. They can store health data, GPS data, sleep data and more. However, a type of application that is also interesting to analyze is running applications. The focus of these applications is related to outdoor running and other types of physical activities. Usually, these applications also function as fitness-tracking social networks, where one connects with other users and shares their running activities, sometimes to compare performances. The difference between these and companion applications is that they do not require the user to wear a smartwatch or smartband, as it is sufficient to use a smartphone with GPS and step counter capabilities. As running applications store data such as GPS coordinates and the date/time of run workouts, they can be instrumental in digital forensic analysis. Because of all their benefits, fitness applications have grown in numbers and users in recent years. In 2019, the major app stores featured over 350,000 healthcare and fitness applications, resulting in an annual download count of 3.7 billion [10]. This prevalence increases the likelihood of their relevance in a criminal investigation. The high volume makes these types of applications a target for cybercriminals intending to steal valuable private data related to the applications' users. Since these applications handle private data, security and privacy should be their top priority, considering the number of regulations and legislation that they must follow. However, this is not always the case. Various studies have shown failures and shortcomings in the security and privacy of these applications. Scott et al. [11] studied fitness applications, showing that most stored data are in plain text and do not encrypt their communication. These facts made health and fitness apps a target of attacks that could cause the leak of millions of users' data. Another issue is the poor privacy features implemented in some of these applications, which could be exploited by users with malicious intent, such as stalking another person by studying their GPS activities. A famous example is the Strava application, where a man used it to stalk his ex-partner [12]. In 2022, it was revealed that Strava harbored a security vulnerability capable of enabling user tracking, even for the ones who had set the strictest privacy settings allowed by the application. The failure could be exploited by uploading fake running segments, allowing malicious users to learn the identities and past routes of Strava's users in the area [13]. In recent years, applications claim to have significantly evolved in security and privacy concerns by adding various privacy features, often due to discovered failures. However, some of these problems remain, and many applications still store a large amount of sensitive data, making them vulnerable to data leaks. In this work, we conduct a forensic analysis of six running applications. As demonstrated later, Android applications were selected due to their widespread popularity, indicated by download numbers in the millions. All running applications except Strava are linked to well-known and popular sportswear brands.