In Firefox before 69.0, given a compromised sandboxed content process due to a separate vulnerability, it is possible to escape that sandbox by loading accounts.firefox.com in that process and forcing a log-in to a malicious Firefox Sync account. Preference settings that disable the sandbox are then synchronized to the local machine and the compromised browser would restart without the sandbox if a crash is triggered.
In Firefox before 69.0, given a compromised sandboxed content process due to a separate vulnerability, it is possible to escape that sandbox by loading accounts.firefox.com in that process and forcing a log-in to a malicious Firefox Sync account. Preference settings that disable the sandbox are then synchronized to the local machine and the compromised browser would restart without the sandbox if a crash is triggered.
https://www.mozilla.org/en-US/security/advisories/mfsa2019-25/#CVE-2019-9812 https://bugzilla.mozilla.org/show_bug.cgi?id=1538008 https://bugzilla.mozilla.org/show_bug.cgi?id=1538015
Vulmon