Vulnerability identifier: #VU4814

Vulnerability risk: Critical

CVSSv3.1: 9.2 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H/E:H/RL:O/RC:C]

CVE-ID: CVE-2016-0034

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Microsoft Silverlight
Client/Desktop applications / Plugins for browsers, ActiveX components

Vendor: Microsoft

Description
The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The weakness exists due to an error when parsing strings with a malicious decoder that can return negative offsets. A remote attacker can create a specially crafted content, trick the victim into opening it, replace unsafe object headers with contents provided by an attacker and execute arbitrary code with privileges of the current user.

Successful exploitation of the vulnerability results in arbitrary code execution on the vulnerable system.

Note: the vulnerability was being actively exploited.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Microsoft Silverlight: 5

---

External links
http://technet.microsoft.com/en-us/library/security/ms16-006

---

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?

Yes. This vulnerability is being exploited in the wild.