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8/15/2008
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Randy George
Randy George
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Cisco Releases Security Advisory On WebEx Client ActiveX Control

According to Cisco, the WebEx Meeting Manager client software includes atucfobj.dll, a DLL that allows meeting participants to view Unicode fonts. This library contains a buffer overflow vulnerability that could allow an attacker to execute arbitrary code on your system. Your WebEx provider must patch its servers in order for you to be protected. Read on to find out how to check.

According to Cisco, the WebEx Meeting Manager client software includes atucfobj.dll, a DLL that allows meeting participants to view Unicode fonts. This library contains a buffer overflow vulnerability that could allow an attacker to execute arbitrary code on your system. Your WebEx provider must patch its servers in order for you to be protected. Read on to find out how to check.WebEx is a leading remote support platform for organizations worldwide, so this particular vulnerability is bound to impact lots of IT shops. In fact, I just discovered my very own Web provider is still vulnerable!

The most frustrating thing about this vulnerability is that you are at the mercy of your WebEx provider. That's because the WebEx provider's server automatically updates the WebEx client upon login to the latest version it has to distribute. And if the WebEx presenter is distributing a vulnerable client, you will be downgraded to a vulnerable client despite any attempt to upgrade to a nonvulnerable client.

Most WebEx presenters are on the WBS26 version of the software. Here's a quick snippet from the Cisco alert that will help you determine if you and your WebEx presenter are vulnerable.

"For the WBS 26 version: 1. Browse to the WebEx meeting server at https://.webex.com/. 2. Select Support from the left side of the Web page. 3. Select Downloads from the left side of the Web page. 4. The version of the client software that is provided by the server is listed next to Client build. For WebEx servers that are running WBS 26, the first fixed version is 26.49.9.2838. Client build versions prior to 26.49.9.2838 are vulnerable."

Of course, my provider is distributing the 26.49.8.2689 client. You can read the full security release here.

http://www.cisco.com/warp/public/707/cisco-sa-20080814-webex.shtml

Pardon me while I get on the phone with my WebEx provider to try to resolve this issue!

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