August 9, 2025
2 min read
Flash cookies, also known as Local Shared Objects (LSOs), are data files stored on a user’s device by websites utilizing Adobe Flash Player technology. Unlike traditional HTTP cookies, which are managed and stored within the browser, Flash cookies are saved in a separate location on the user's system—specifically within Adobe files—making them less accessible to standard browser controls and privacy tools. This distinct storage mechanism enables websites to persistently track user preferences and behaviors even after normal cookies have been cleared.
Analysis of Flash cookie mechanisms demonstrates that their primary function extends beyond simple session management to include persistent user identification and cross-site tracking. For instance:
Empirical studies show that many websites deploy Flash cookies to circumvent user attempts at privacy protection. Soltani et al. (2010) found that "at least 54 out of the top 100 websites used LSOs to store information previously deleted by users," effectively undermining privacy controls. This practice raises significant privacy and ethical concerns, as users remain largely unaware of these files and lack efficient means for managing or deleting them through standard browser interfaces.
Management of Flash cookies is possible only through specialized Adobe Flash Player settings panels, not typical browser privacy settings. As a result, users must take additional steps to access, modify, or delete these objects—an obstacle for the average user concerned about digital privacy.
In summary, key findings show that:
These characteristics underscore the importance of regulating or redesigning web storage mechanisms to align with user privacy expectations and legal requirements.
