Vulnerability identifier: #VU7074

Vulnerability risk: Low

CVSSv3.1: 7.7 [CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2017-7761

CWE-ID: CWE-427

Exploitation vector: Local

Exploit availability: No

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

Vendor: Mozilla

Description
The vulnerability allows a local attacker to gain elevated privileges on the target system.

The vulnerability exists in the Mozilla Maintenance Service helper.exe application due to insecure .dll loading mechanism when opening files. A local attacker can place a specially crafted .dll file along with junction protected files on a remote SBM or WebDAV share, trick the victim into opening legitimate media file and execute arbitrary code on the target system with system privileges.

Successful exploitation of the vulnerability may result in system compromise.

Mitigation
Update to version 52.2.

Vulnerable software versions

Firefox ESR: 52.0.1, 45.0 - 45.8, 38.0 - 38.8.0

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External links
http://www.mozilla.org/en-US/security/advisories/mfsa2017-16/

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Q & A

Can this vulnerability be exploited remotely?

No. This vulnerability can be exploited locally. The attacker should have authentication credentials and successfully authenticate on the system.

Is there known malware, which exploits this vulnerability?

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