Vulnerability identifier: #VU20824

Vulnerability risk: Medium

CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2019-9812

CWE-ID: CWE-264

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Mozilla Firefox
Client/Desktop applications / Web browsers

Vendor: Mozilla

Description

The vulnerability allows a remote attacker to escape sandbox restrictions.

The vulnerability exists due to a combination of issues related to a compromised sandboxed content and the Firefox Sync ability to  synchronize data with the malicious account. A remote attacker can can compromise a sandboxed content process using a different vulnerability, and then 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.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Mozilla Firefox: 66.0.2 - 68.0.2

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External links
http://www.mozilla.org/en-US/security/advisories/mfsa2019-25/
http://www.zerodayinitiative.com/advisories/ZDI-19-782/

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.