Because of this, I cannot "come up with a feature" for the file itself, as it likely contains stolen information or malicious content.

These logs are often created by "infostealer" malware. EDR tools can detect the behavior of malware attempting to scrape browser data (passwords, cookies, and autofill info) before it is exfiltrated.

Disable the "Save Passwords" feature in browsers, as this is the primary target for infostealers. Use a dedicated, encrypted password manager instead.