Adobe Patches 0-day Flaw Used In Stealth Attacks

Wolfgang Kandek

Last updated on: September 7, 2020

Yesterday Adobe Systems updated its Reader product to fix a total of eight vulnerabilities. Out of the eight vulnerabilities, six allow remote code execution and are critical. One of the flaws addressed was CVE-2009-4324, the 0-day vulnerability which has had exploits in the wild since December 14 2009, roughly a month ago. This vulnerability is exploited by including malicious code in a PDF document and triggered by executing an embedded JavaScript program. The PDF can be delivered through e-mail or downloaded from a website, making it a fairly easy attack to execute. Interestingly enough it seems that this particular flaw was used in against Adobe itself as pointed out by Elinor Mills at CNET.

Adobe has introduced two interesting security tools in the last two releases of the Reader product – one is an integrated update mechanism that will eventually default to automatic and silent updates. This mechanism is currently in beta and being tested with part of the installed base. The second tool is a internal blacklist that allows hackers to disable specific JavaScript functions. Adobe recently provided guidance on how to mitigate the December 0-day by using this tool. Both tools are in their initial stages but look very promising.

The fixed versions are now Reader v9.3 and v8.2 . What is important for Adobe Reader v7 users to know is that v7 is now out of support (as of 12/28/2009 – see: and is not being updated anymore with Security fixes. However, it is impacted by the December 0-day. IT administrators should take inventory of their v7 users and upgrade them to the current standard of v9.


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