ID: IRCNE2013011721
Date: 2013-01-08
According to "computerworld", a hacker claims to have found a method of bypassing the code integrity mechanism in Windows RT, therefore allowing for desktop-style programs to be installed on the platform.
The hacker, who uses the online moniker "clrokr", documented the bypass method in a blog post on Sunday.
Windows RT is a special version of Microsoft Windows designed for lightweight PCs and tablets that are based on the ARM architecture, including Microsoft's Surface tablet. Compared to Windows 8, Windows RT only allows Metro apps downloaded from the Windows Store to be installed. These applications are designed only for the Metro interface and don't have access to the regular Windows desktop.
According to clrokr, the restriction of installing only Metro-style apps on Windows RT is enforced through a code integrity mechanism that checks the application's signature before allowing it to be installed.
"Deep in the kernel, in a hashed and signed data section protected by UEFI's Secure Boot, lies a byte that represents the minimum signing level," clrokr said. The minimum signing level enforced by Windows RT can be changed by exploiting a vulnerability in the Windows kernel that had existed for some time and is also present in Windows RT, in order to modify that special byte in memory, clrokr said. The hacker decided to disclose the bypass method publicly.
Microsoft is aware of the disclosed exploit and is looking into the matter. "We are actively investigating this report and will take appropriate action to help protect customers," the company said Monday via email.
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