Adobe Flash - Action Script 3 opaqueBackground Use-After-Free Vulnerability

Number: AL15-009
Date: 11 July 2015


The purpose of this alert is to bring attention to a recently discovered vulnerability in the Actionscript 3 opaqueBackGround property of Adobe Flash Player.  Exploitation of this vulnerability could ultimately allow an unauthenticated attacker to execute arbitrary code on the system.


Adobe Flash Player versions 9.0 through contain a use-after-free vulnerability in the AS3 opaqueBackground property.  Attackers exploiting this memory flaw can cause programs to crash and execution of arbitrary code with system privileges.  Attack vectors can include baiting users into visiting sites containing flawed Flash content and through use of specially crafted Microsoft Office documents.

Suggested action

CCIRC recommends that owner/operators utilize Microsoft's Enhanced Mitigation Experience Toolkit (EMET) to help prevent exploitation of this vulnerability.  In particular, Attack Surface Reduction (ASR) can be configured to help restrict Microsoft Office and Internet Explorer from loading the Flash ActiveX control.


Note to Readers

In support of Public Safety's mission to build a safe and resilient Canada, CCIRC's mandate is to help ensure the security and resilience of the vital non-federal government cyber systems that underpin Canada's national security, public safety and economic prosperity. As Canada's computer security incident response team, CCIRC is Canada's national coordination centre for the prevention and mitigation of, preparedness for, response to, and recovery from cyber incidents on non-federal government systems. It does this by providing authoritative advice and support, and coordinating information sharing and incident response.

Please note, CCIRC PGP key has recently been updated.

For general information, please contact Public Safety Canada's Public Affairs division at:

Telephone: 613-944-4875 or 1-800-830-3118
Fax: 613-998-9589

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