Fiabilité des données générées par les applications comme preuve de sécurité

Digital forensic investigators examine application-created logs and database records to reconstruct what happened inside an application and to detect security events. The reliability of these data for the task, however, is not guaranteed. Application logs are often designed for debugging rather than forensic analysis, leaving out information needed to explain the application's security-related events. Mobile applications are also frequently updated, and each update can significantly modify the source of evidence from the application database. Such structural changes may result in critical evidence being lost for extraction or introduce new evidence that previous acquisition methods fail to capture. These variables raise an important question: to what extent can application-generated data be considered reliable for forensic purposes, and under what conditions does it fail to provide the evidence investigators need? To address this question, application-generated data for forensic evidence was examined through three complementary studies. The first measured how well application logs support security-focused analysis by evaluating their logs for forensic tasks. The second study investigated whether log statements are consistently placed according to the defined log placement for security along critical execution paths. It also introduced an automated tool to detect missing or inconsistently placed logs that could affect the reliability of application log data. The third examines the reliability of forensic acquisition and completeness of digital evidence under database schema changes across application versions, evaluating how structural evolution directly impacts the accuracy and success of forensic acquisition. Together, these studies provide a systematic understanding of application-produced digital data that often falls short as reliable security evidence, and outline the challenges that must be addressed to strengthen the evidential value of the application.