Microsoft Fixes SSL Miscue

Wednesday, September 21, 2011 @ 03:09 PM gHale


Microsoft re-released an update for Windows XP to correct an issue that left users vulnerable to potential “man-in-the-middle” attacks.

The update addressed a problem introduced last week when Microsoft blocked six additional root certificates issued by DigiNotar cross-signed by a pair of other certificate authorities (CAs).

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Servers run by Dutch CA DigiNotar suffered a hack in June, and attackers stole over 500 SSL (secure socket layer) certificates, including quite a few used by the Dutch government.

Websites and browsers use SSL certificates to identify a site as legitimate — that gmail.com or hotmail.com are actually what they claim — and illegally-obtained certificates can disguise unauthorized domains using “man-in-the-middle” attacks to snoop on digital communications and harvest account credentials.

One certificate stolen from DigiNotar was able to spy on 300,000 Iranians for about a month this summer.

Microsoft said there was a flaw in the update it shipped to Windows XP and Server 2003 users last Tuesday.

“The versions…for Windows XP and for Windows Server 2003 contained only the latest six digital certificates cross-signed by GTE and Entrust,” said Microsoft in a revised support document. “These versions of the update did not contain the digital certificates that were included in [earlier updates].”

The earlier update, delivered by Microsoft on Sept. 6, blocked five DigiNotar root certificates.

“If you installed update 2616676 and had not already installed update 2607712 or update 2524375, your system would not have been protected from the use of fraudulent digital certificates,” Microsoft said.

The re-released update for XP and Server 2003 is now in Windows Update, Microsoft said. Customers who do not have Automatic Updates enabled should manually download and install the new version of the DigiNotar blocker.

The update miscue did not affect Windows Vista, Windows 7, Server 2008 and Server 2008 R2, Microsoft said.



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