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‘Gadget’ in the middle: Flame malware spreading vector identified

Aleks, June 04

In our FAQ on Flame posted on May 28, 2012, we postulated there might be a still undiscovered zero-day vulnerability in Flame:

“At the moment, we haven’t seen use of any 0-days; however, the worm is known to have infected fully-patched Windows 7 systems through the network, which might indicate the presence of a high risk 0-day.”

Our suspicion was heightened because fully patched Windows 7 machines were being infected over the network in a very suspicious manner.

We can now confirm this is the main purpose of a special module of Flame called “Gadget” together with another module called “Munch”.

(NOTE: It’s important to understand that the initial Flame infection could still be happening through zero-day vulnerabilities. The “Gadget” module is simply used to spread within a network from a machine that is already infected with the malware).

The “Gadget” and “Munch” modules implement an interesting man-in-the-middle attack against other computers in a network.

When a machine tries to connect to Microsoft’s Windows Update, it redirects the connection through an infected machine and it sends a fake, malicious Windows Update to the client.

The fake update claims to be the following:

“update description=”Allows you to display gadgets on your desktop.”
displayName=”Desktop Gadget Platform” name=”WindowsGadgetPlatform”

[…]

Important information: One June 4th, 2012, Microsoft released a number of blog posts and an Update for Windows which is blocking three fraudulent certificates used by Flame. We recommend that Windows users apply this update immediately.

Microsoft SRD blog:http://blogs.technet.com/b/srd/archive/2012/06/03/microsoft-certification-authority-signing-certificates-added-to-the-untrusted-certificate-store.aspx

Microsoft security advisory 2718704:http://technet.microsoft.com/en-us/security/advisory/2718704

MSRC blog:http://blogs.technet.com/b/msrc/archive/2012/06/03/microsoft-releases-security-advisory-2718704.aspx