Feeds

'Super-secret' debugger discovered in AMD CPUs

Password-protected feature goes beyond x86

Application security programs and practises

A hardware hacker has discovered a secret debugging feature hidden in all AMD chips made in the past decade.

The password-protected debugger came as a shock to reverse-engineers who have hungered for an on-chip mechanism for performing conditional and direct-hardware breakpoint operations. Although AMD has built the firmware-controlled feature into all chips since the Athlon XP, the company kept it a closely guarded secret that was only disclosed late last week by a hacker who goes by the name Czernobyl.

“AMD processors (Athlon XP and better) have included firmware-based debugging features that expand greatly over standard, architecturally defined capabilities of x86,” the hacker wrote. “For some reason, though, AMD has been tightly secretive about these features; hint of their existence was gained by glancing at CBID's page.”

To put a chip into developer mode, a user must first enter what amounts to a password — 9C5A203A — into the CPU's EDI register. Czernobyl was able to deduce the secret setting by brute forcing the key.

Presumably, the debugger is an internal AMD utility used during development and then turned off before shipping. Its discovery by world + dog means that everyday users may have powerful new tools to hack, debug, and reverse-engineer their hardware. Now that its existence and the instructions for turning it on are known, the real discoveries about exactly what can be done with it are sure to commence. ®

The Power of One Infographic

Whitepapers

Implementing global e-invoicing with guaranteed legal certainty
Explaining the role local tax compliance plays in successful supply chain management and e-business and how leading global brands are addressing this.
Consolidation: The Foundation for IT Business Transformation
In this whitepaper learn how effective consolidation of IT and business resources can enable multiple, meaningful business benefits.
Application security programs and practises
Follow a few strategies and your organization can gain the full benefits of open source and the cloud without compromising the security of your applications.
How modern custom applications can spur business growth
Learn how to create, deploy and manage custom applications without consuming or expanding the need for scarce, expensive IT resources.
Securing Web Applications Made Simple and Scalable
Learn how automated security testing can provide a simple and scalable way to protect your web applications.