- These vulnerabilities affect: Adobe Flash Player running on all platforms, Adobe Air, and all versions of Reader X
- How an attacker exploits it: By enticing users to visit a website containing malicious Flash content (or into downloading and opening a malicious PDF)
- Impact: In the worst case, an attacker can execute code on the user’s computer, potentially gaining control of it
- What to do: Download and install the latest version of Adobe Flash Player for your platform (see Solution section for Reader X flaw mitigation)
Adobe Flash Player displays interactive, animated web content called Flash. Although Flash is optional, 99% of PC users download and install it to view multimedia web content. It runs on many operating systems, including mobile operating systems like Android.
This week, Adobe released a security bulletin describing seven security vulnerabilities (based on CVE numbers) that affect Flash Player running on any platform. It doesn’t describe the flaws in much technical detail, other than mentioning they consist of buffer overflow vulnerabilities and other types of memory corruption flaws. That said, Adobe does warn that if an attacker can entice one of your users to visit a malicious website containing specially crafted Flash content, he could exploit any of these flaws to execute code on that user’s computer, with that user’s privileges. If your Windows users have local administrator privileges, an attacker could exploit this flaw to gain full control of their PCs.
Though it doesn’t look like attackers are exploiting these Flash flaws in the wild yet, Adobe rates them as “Priority 1” for Windows users, and recommends you apply the Windows updates within 72 hours. These vulnerabilities also affect other platforms as well, though not as severely. I recommend you update any Flash capable device as soon as you can.
In semi-related news, a Russian security group warns they have found attackers exploiting a zero day Adobe Reader X vulnerability in the wild. The flaw affects the most recent versions of the popular PDF reader, and can even escape its sandbox protection. In short, if you interact with the wrong PDF document, an attacker could gain complete control of your computer. The good news is the web version of this attack does require a victim to close and re-open their browser to succeed, making it a little harder to pull off.
At the time of writing, Adobe has yet to respond to this zero day report, and has not released a patch. Your primary recourse is to try to avoid unsolicited PDF documents. You can also leverage WatchGuard’s file-blocking capabilities to temporarily restrict your user’s access to PDF files, though this will also prevent them from downloading legitimate ones, too.
One final note: Next month Adobe plans to sync their Flash updates with Microsoft’s Patch Tuesday updates. So you can expect all future Adobe updates (other than perhaps emergency ones), on the second Tuesday of the month.
Adobe has released new versions of Flash Player to fix these issues. If you allow Adobe Flash in your network, you should download and install the new versions immediately. If you’ve enabled Flash Player’s recent “silent update” option, you will receive this update automatically.
You can download Flash for your computer at the link provided below. See the bulletin’s “Affected Software” section for more details on getting Flash updates for other platforms:
For All WatchGuard Users:
If you choose, you can configure the HTTP proxy on your XTM appliance to block Flash or PDF content. Keep in mind, doing so blocks all such content, whether legitimate or malicious.
Our proxies offer many ways for you to block files and content, including by file extension, MIME type, or by using very specific hexidecimal patterns found in the body of a message – a technique sometimes referred to as Magic Byte detection. Below I list the various ways you can identify these various files:
- .flv – Adobe Flash file (file typically used on websites)
- .fla – Flash movie file
- .f4v – Flash video file
- .f4p – Protected Flash video file
- .f4a – Flash audio file
- .f4b – Flash audiobook file
- .PDF – Adobe Reader document
- video/mp4 (used for more than just Flash)
- audio/mp4 (used for more than just Flash)
FILExt.com reported Magic Byte Pattern:
- FLV Hex: 46 4C 56 01
- FLV ASCII: FLV
- FLA Hex: D0 CF 11 E0 A1 B1 1A E1 00
- PDF Hex: 25 50 44 46 2D 31 2E
- PDF ASCII: %PDF-1
(Keep in mind, not all the Hex and ASCII patterns shared here are appropriate for content blocking. If the pattern is too short, or not unique enough, blocking with them could result in many false positives.)
If you decide you want to block these files, the links below contain instructions that will help you configure your Firebox proxy’s content blocking features using the file and MIME information listed above.
- XTM Appliance with WSM 11.x
- Firebox X Edge running 10.x
- Firebox X Core and X Peak running Fireware 10.x
Adobe has released updates to fix these Flash vulnerabilities, however, they have not yet responded to the Reader X zero day.
This alert was researched and written by Corey Nachreiner, CISSP (@SecAdept)
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