1) Security bypass

Risk: Critical

CVSSv3: 8.9 [CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H/E:F/RL:O/RC:C] [PCI]

CVE-ID: CVE-2015-4495

CWE-ID: CWE-20 - Improper Input Validation

Exploit availability: Yes

Description

The vulnerabiity allows a remote attacker to bypass security restrictions on the target system.

The weakness exists due to improper input validation. A remote attacker can create a specially crafted PDF file, trick the victim into opening it, bypass same-origin policy and inject arbitrary JavaScript into the built-in PDF Viewer to gain access to arbitrary files on the system.

Successful exploitation of this vulnerability may result in access to local files and privilege escalation, leading to system compromise.

Note: the vulnerability was being actively exploited.

Mitigation

Update Mozilla Firefox to version 39.0.3, Mozilla Firefox ESR to version 38.1, Mozilla Firefox OS to version 2.2.

Vulnerable software versions

Firefox ESR: 38.0, 38.1.0, 38.1.1

Mozilla Firefox: 38.0, 38.0.1, 38.0.5, 39.0, 39.0.3

Firefox OS: 1.0, 1.0.1, 1.1.0, 1.1.1, 1.2.0, 1.3.0, 1.4.0, 2.0, 2.1, 2.2

CPE

• cpe:/a:mozilla:firefox_esr:38.1.1:
• cpe:/a:mozilla:firefox_esr:38.1.0:
• cpe:/a:mozilla:firefox_esr:38.0:
• cpe:/a:mozilla:mozilla_firefox:38.0:
• cpe:/a:mozilla:mozilla_firefox:38.0.1:
• cpe:/a:mozilla:mozilla_firefox:38.0.5:
• cpe:/a:mozilla:mozilla_firefox:39.0:
• cpe:/a:mozilla:mozilla_firefox:39.0.3:
• cpe:/a:mozilla:firefox_os:1.0:
• cpe:/a:mozilla:firefox_os:1.0.1:
• cpe:/a:mozilla:firefox_os:1.1.0:
• cpe:/a:mozilla:firefox_os:1.1.1:
• cpe:/a:mozilla:firefox_os:1.2.0:
• cpe:/a:mozilla:firefox_os:1.3.0:
• cpe:/a:mozilla:firefox_os:1.4.0:
• cpe:/a:mozilla:firefox_os:2.0:
• cpe:/a:mozilla:firefox_os:2.1:
• cpe:/a:mozilla:firefox_os:2.2:

External links

https://www.mozilla.org/en-US/security/advisories/mfsa2015-78/

Q & A

Can this vulnerability be exploited remotely?

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

How the attacker can exploit this vulnerability?

The attacker would have to trick the victim to visit a specially crafted website.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, a fully functional exploit for this vulnerability is available.