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10 Nov 2005

Trojan horse exploits Sony DRM copy protection vulnerability

Sophos issues tool to detect and disable "cloaking" flaw exploited by Trojans

Music CD
The Trojan horse exploits a vulnerability introduced by Sony's CD copy protection software.

Experts at SophosLabs™, Sophos's global network of virus and spam analysis centers, have detected a new Trojan horse that exploits the controversial Sony DRM (Digital Rights Management) copy protection included on some of the music giant's CDs.

The Troj/Stinx-E Trojan horse appears to have been deliberately spammed out to email addresses, posing as a message from a British business magazine.

Typical emails look as follows:

Subject: Photo Approval Deadline

Message body:
Your photograph was forwarded to us as part of an article we are publishing for our December edition of Total Business Monthly. Can you check over the format and get back to us with your approval or any changes? If the picture is not to your liking then please send a preferred one. We have attached the photo with the article here.

If the attached program is run, the Trojan horse copies itself to a file called $sys$drv.exe. Any file with $sys$ in its name is automatically cloaked by Sony BMG's copy-protection code, making it invisible on computers which have used CDs carrying Sony's copy protection.

"Despite its good intentions in stopping music piracy, Sony's DRM copy protection has opened up a vulnerability which hackers and virus writers are now exploiting," said Graham Cluley, senior technology consultant for Sophos. "We wouldn't be surprised if more malware authors try and take advantage of this security hole, and consumers and businesses alike would be sensible to protect themselves at the earliest opportunity."

Detect and disable "cloaking flaw" in Sony's DRM copy-protection

Sophos has issued a tool which will detect the existence of Sony's DRM copy-protection on Windows computers, disable its "cloaking" function, and prevent that functionality from re-installing. The tool also detects versions of the Troj/Stinx Trojan horse which exploit the Sony vulnerability.

"Sophos is acting on customers' concern that the software on Sony's CDs is introducing a vulnerability which hackers and virus writers are able to exploit," explained Cluley. "We will give customers the ability to determine if their computers suffer from the vulnerability and remove it if necessary."

Sophos recommends that businesses ensure their computers are kept automatically up-to-date with the very latest anti-virus software.

About Sophos

More than 100 million users in 150 countries rely on Sophos as the best protection against complex threats and data loss. Sophos is committed to providing complete security solutions that are simple to deploy, manage, and use and that deliver the industry's lowest total cost of ownership. Sophos offers award-winning encryption, endpoint security, web, email, mobile and network security solutions backed by SophosLabs - a global network of threat intelligence centers.

Sophos is headquartered in Boston, US and Oxford, UK. More information is available at