"You Have to Ignore the Dangers": User Perceptions of the Security and Privacy Benefits of WhatsApp Mods

WhatsApp is the most popular social messaging platform, and modified versions (or “mods”) of the official WhatsApp are increasingly popular. Mods advertise additional features and customization. However, some of these features, e.g., retaining deleted messages and statuses, enable mod users to subvert the privacy of others, and have the potential for seri-ous security and privacy implications. In this study, we explore user perspectives of WhatsApp mods through an interview study $(n=20)$ of mod users in Kenya, one of the countries with the highest WhatsApp mod usage. Many turned to WhatsApp mods for their “advanced” features to protect themselves (e.g., “anti-delete” for legal liability), while others admitted to using mod features to hide their behavior or to stalk others. To understand how users' expectations of WhatsApp mods align with the apps' behavior, we identify and analyze 13 instances of the most common mod (GB WhatsApp). While WhatsApp mods contained the features they claimed to offer, some participants incorrectly believed that features currently available in the official app only existed in mods. Additionally, several mods were significantly over-permissioned compared to the official WhatsApp, despite participants believing that they requested the same permissions as the official app. While almost half of participants indicated they trust mods more than the official WhatsApp, we found two mods contained malware. The use of WhatsApp mods poses risks to mod users and those they communicate with, but also empowers users in ways that the official app does not. We caution developers and mod users to do their due diligence before using or distributing mods.