Genotype Extraction and False Relative Attacks: Security Risks to Third-Party Genetic Genealogy Services Beyond Identity Inference

—Customers of direct-to-consumer (DTC) genetic testing services routinely download their raw genetic data and give it to third-party companies that support additional features. One type of analysis, called genetic genealogy, uses genetic data and genealogical methods to find new relatives. While genetic genealogy is quite popular, it has raised new privacy concerns. Genetic genealogy services can be leveraged to find the person corresponding to anonymous genetic data and have been used dozens of times by law enforcement to solve crimes. We hypothesized that the open design and broad API offered by some genetic genealogy services raise other significant security and privacy issues. To test this hypothesis, we analyzed the security practices of GEDmatch, the largest third-party genetic genealogy service. Here, we experimentally show how the GEDmatch API is vulnerable to a number of attacks from an adversary that only uploads normally formatted genetic data files and runs standard queries. Using a small number of specifically designed files and queries, an attacker can extract a large percentage of the genetic markers from other users; 92% of markers can be extracted with 98% accuracy, including hundreds of medically sensitive markers. We also find that an adversary can construct genetic data files that falsely appear like relatives to other samples in the database; in certain situations, these false relatives can be used to make the re-identification of genetic data more difficult. These attacks are possible because of the rich set of features supported by the API, including detailed visualizations, that are meant to enhance usability. We conclude with security recommendations for genetic genealogy services.