10 - TA15-195A

Overview

Used in conjunction, recently disclosed vulnerabilities in Adobe Flash and Microsoft Windows may allow a remote attacker to execute arbitrary code with system privileges. Since attackers continue to target and find new vulnerabilities in popular, Internet-facing software, updating is not sufficient, and it is important to use exploit mitigation and other defensive techniques.

Description

The following vulnerabilities illustrate the need for ongoing mitigation techniques and prioritization of updates for highly targeted software:

• Adobe Flash use-after-free and memory corruption vulnerabilities (CVE-2015-5119, CVE-2015-5122, CVE-2015-5123) Adobe Flash Player contains critical vulnerabilities within the ActionScript 3 ByteArray, opaqueBackground and BitmapData classes. Exploitation of these vulnerabilities could allow a remote attacker to execute arbitrary code on a vulnerable system.


• Microsoft Windows Adobe Type Manager privilege escalation vulnerability (CVE-2015-2387)
  The Adobe Type Manager module contains a memory corruption vulnerability, which can allow an attacker to obtain system privileges on an affected Windows system. The Adobe Type Manager is a Microsoft Windows component present in every version since NT 4.0. The primary impact of exploiting this vulnerability is local privilege escalation.

Vulnerability Chaining

By convincing a user to visit a website or open a file containing specially crafted Flash content, an attacker could combine any one of the three Adobe Flash vulnerabilities with the Microsoft Windows vulnerability to take full control of an affected system.

A common attack vector for exploiting a Flash vulnerability is to entice a user to load Flash content in a web browser, and most web browsers have Flash installed and enabled. A second attack vector for Flash vulnerabilities is through a file (such as an email attachment) that embeds Flash content. Another technique leverages Object Linking and Embedding (OLE) capabilities in Microsoft Office documents to automatically download Flash content from a remote server.

An attacker who is able to execute arbitrary code through the Flash vulnerability could exploit the Adobe Type Manager vulnerability to gain elevated system privileges. The Adobe Type Manager vulnerability allows the attacker to bypass sandbox defenses (such as those found in Adobe Reader and Google Chrome) and low integrity protections (such as Protected Mode Internet Explorer and Protected View for Microsoft Office).

Impact

The Adobe Flash vulnerabilities can allow a remote attacker to execute arbitrary code. Exploitation of the Adobe Type Manager vulnerability could then allow the attacker to execute code with system https://www.microsoft.com/en-us/download/details.aspx?id=46366privileges.

Solution

Since attackers regularly target widely deployed, Internet-accessible software such as Adobe Flash and Microsoft Windows, it is important to prioritize updates for these products to defend against known vulnerabilities.

Since attackers regularly discover new vulnerabilities for which updates do not exist, it is important to enable exploit mitigation and other defensive techniques.

Apply Security Updates

The Adobe Flash vulnerabilities (CVE-2015-5119, CVE-2015-5122, CVE-2015-5123) are addressed in Adobe Security Bulletins APSB15-16 and APSB15-18. Users are encouraged to review the Bulletins and apply the necessary updates.

The Microsoft Windows Adobe Type Manager vulnerability (CVE-2015-2387) is addressed in Microsoft security Bulletin MS15-077. Users are encouraged to review the Bulletin and apply the necessary updates.

Additional information regarding the vulnerabilities can be found in Vulnerability Notes VU#561288, VU#338736, VU#918568, and VU#103336.

Limit Flash Content

Do not run untrusted Flash content. Most web browsers have Flash enabled by default, however, it may be possible to enable click-to-play features. For information see  http://www.howtogeek.com/188059/how-to-enable-click-to-play-plugins-in-every-web-browser/

Use the Microsoft Enhanced Mitigation Experience Toolkit (EMET)

EMET can be used to help prevent exploitation of the Flash vulnerabilities. In particular, Attack Surface Reduction (ASR) can be configured to help restrict Microsoft Office and Internet Explorer from loading the Flash ActiveX control. See the following link for additional information: http://www.microsoft.com/en-us/download/details.aspx?id=46366