Patch Tuesday Fixes Critical Bluetooth Flaw in Windows 7

Patch Tuesday has arrived. As expected, Microsoft released a relatively small number of patches for July, but that is no reason for IT admins to let their guard down–especially when one of the patches is a Critical update for Windows 7 and Windows Vista.

There are three security bulletins rated as Important that impact Windows and Microsoft Office. One is related to Microsoft Visio, one is connected to the client / server runtime subsystem, and the third has to do with kernel-mode drivers. But, the security bulletin that is hogging the attention this month is MS11-053.

According to Microsoft, the critical flaw lays in the Windows Bluetooth Stack–the driver that enables Windows to connect with Bluetooth devices. An attacker may be able to remotely compromise and gain full access to a vulnerable system via its Bluetooth networking. Microsoft also points out, though, that this vulnerability only affects systems with Bluetooth capability.

Joshua Talbot, Security Intelligence Manager at Symantec Security Response, explains, “An attacker would exploit this by sending specific malicious data to the targeted computer while establishing a Bluetooth connection,” adding that a successful exploit would grant the attacker complete access to the system without any alert or notification to warn the targeted user that a rogue PC has connected via Bluetooth.

Andrew Storms, Director of Security Operations for nCircle, agrees that MS11-053 is serious, but with some caveats. “This seems pretty scary at first glance, but it’s a good idea to consider the details of the vulnerability before getting all worked up about it. This bug requires that Bluetooth on a PC be set in ‘discoverable’ mode, and this is not the default setting. If Bluetooth is not set to ‘discoverable’, the attacker will need to use another approach to attack the PC before they can take advantage of the Bluetooth bug.”

Talbot concurs, stating, “It’s unlikely it could be used in a widespread attack because an attacker would have to be within Bluetooth range to exploit it. Thus, a specific target would likely already have to be identified and that person’s whereabouts known to the attacker.”

The reason the flaw only impacts Windows 7 and Windows Vista, and not legacy platforms like Windows XP, is that Windows XP doesn’t have the underlying Bluetooth support that is the root of the problem. Although older OS platforms are generally more vulnerable and insecure, when a flaw impacts a newer technology that didn’t even exist in the prior OS, the legacy platform is obviously not affected.

Jason Miller, Manager of Research and Development for VMware Security, stresses, “If you have mobile users working outside of your office, you will want to look at patching these machines as soon as possible.”