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BlackBerry squashes W-TIFF-F bug that's ripe for malware squirters

Picture this: BES servers hacked by evil image files

BlackBerry has patched a security vulnerability that allowed hackers to execute malicious code on systems running its BlackBerry Enterprise Server (BES) software.

The bug, rated as "high severity", is triggered by specially crafted TIFF image files that travel into BES as users visit webpages, receive emails and exchange instant message conversations.

BlackBerry has supplied an update, which it warns must be applied not only to prevent hackers from squirting malicious code onto messaging servers, but also to block potential attempts by miscreants to harness the vulnerability as a means to hack into corporate networks:

Vulnerabilities exist in how the BlackBerry MDS Connection Service and the BlackBerry Messaging Agent process TIFF images for rendering on the BlackBerry smartphone.

Successful exploitation of any of these vulnerabilities might allow an attacker to gain access to and execute code on the BlackBerry Enterprise Server.

Depending on the privileges available to the configured BlackBerry Enterprise Server service account, the attacker might also be able to extend access to other non-segmented parts of the network.

The vulnerability affects messaging servers and not BlackBerry smartphones. The Canadian firm said it had not received any reports of attacks targeting its corporate customers, so there's no need to press the panic button.

Although there's no reason to believe that the flaw has been exploited by baddies, the security bug is nonetheless significant because of its potential for damage against what's traditionally (and with good reason) been regarded as a secure corporate messaging platform, deployed by government and security-sensitive businesses worldwide.

A malicious hacker could create a booby-trapped TIFF image file and either trick a BlackBerry smartphone user into visiting a webpage hosting the image, or embed the malicious image directly into an email or instant message in order to run an attack against vulnerable BlackBerry Enterprise Server (BES) systems. Victims don't even need to be tricked into opening a dodgy TIFF file. Just scrolling over an image embedded within a booby-trapped email would be enough to trigger an assault. Such an attack might take the form of an attempt to crash vulnerable message servers or an attempt to run malicious code.

Although the vulnerability is limited to Blackberry Enterprise Servers running any version below BES 5.0.4 MR2, it does suggest that the days of regarding all images as essentially safe may be numbered, according to security experts.

"This is a bit of a twist on normal exploitation simply because the malicious code is actually inside of an image, something that hasn’t really been done before," notes Fred Touchette, senior security analyst at AppRiver, in a blog post entitled A Picture Is Worth a Thousand Exploits. "Sure, attackers have used executables that pretend to be images, or hide malicious URLs behind image links, but they haven’t been able to use the image itself before now."

Touchette agrees with Graham Cluley of Sophos that the vulnerability is a "serious concern" that needs to be patched sooner rather than later, to guard against possible targeted attacks and corporate espionage based on the vulnerability, which has now become general knowledge.

Corporates can't always interrupt normal operations to apply patches without testing and planned downtime, of course, in which case applying BlackBerry's suggested workarounds is a useful precaution. These workarounds involve either replacing the vulnerable image.dll handler or blocking inline image handling. ®

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