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                                   CERT-Renater

                       Note d'Information No. 2016/VULN326
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DATE                : 14/09/2016

HARDWARE PLATFORM(S): /

OPERATING SYSTEM(S): Systems running Microsoft Silverlight versions 5.

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KB3182373
https://technet.microsoft.com/en-us/library/security/MS16-109
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Microsoft Security Bulletin MS16-109: Security Update for Silverlight
(3182373)

Executive Summary

This security update resolves a vulnerability in Microsoft Silverlight.
The vulnerability could allow remote code execution if a user visits a
compromised website that contains a specially crafted Silverlight
application. An attacker would have no way to force a user to visit a
compromised website. Instead, an attacker would have to convince the
user to visit the website, typically by enticing the user to click a
link in either an email or instant message that takes the user to the
attacker's website.

This security update is rated Important for Microsoft Silverlight 5 and
Microsoft Silverlight 5 Developer Runtime when installed on Mac or all
supported releases of Microsoft Windows.


Affected Software

Microsoft Silverlight 5

Microsoft Silverlight 5 Developer Runtime


Microsoft Silverlight Memory Corruption Vulnerability - CVE-2016-3367

A remote code execution vulnerability exists when Microsoft Silverlight
improperly allows applications to access objects in memory. The
vulnerability could corrupt system memory, which could allow an
attacker to execute arbitrary code. In a web-browsing scenario, an
attacker who successfully exploited this vulnerability could obtain the
same permissions as the currently logged-on user. If a user is logged
on with administrative user rights, an attacker could take complete
control of the affected system. An attacker could then install
programs; view, change, or delete data; or create new accounts with
full user rights. Users whose accounts are configured to have fewer
user rights on the system could be less impacted than users who
operate with administrative user rights.

To exploit the vulnerability, an attacker could host a website that
contains a specially crafted Silverlight application and then convince
a user to visit the compromised website. The attacker could also take
advantage of websites containing specially crafted content, including
those that accept or host user-provided content or advertisements. For
example, an attacker could display specially crafted web content by
using banner advertisements or by using other methods to deliver web
content to affected systems. However, in all cases an attacker would
have no way to force a user to visit a compromised website. Instead,
an attacker would have to convince a user to visit the website,
typically by enticing the user to click a link in either an email or
instant message. The update addresses the vulnerability by correcting
how Microsoft Silverlight allocates memory for inserting and appending
strings in StringBuilder.

The following table contains links to the standard entry for each
vulnerability in the Common Vulnerabilities and Exposures list:

Vulnerability title   CVE number   Publicly disclosed 	Exploited

Microsoft Silverlight Memory
Corruption Vulnerability    CVE-2016-3367 	No 	No


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