Home / Technology / A lot of flaws in AMD chips makes hacks much, much worse

A lot of flaws in AMD chips makes hacks much, much worse

Secure enclaves like the one found on iPhones are meant to be impenetrable strengths that handle tasks that are too sensitive for the main CPUs they work with. The AMD version of that coprocessor contains a series of critical flaws that attackers could exploit to run malware that is almost impossible to detect and has direct access to the most sensitive secrets of a vulnerable computer, a report published on Tuesday warned. The chips also contain what the report calls "backdoors" that hackers can exploit to gain administrative access.

Failures in AMD's EPYC, Ryzen, Ryzen Pro and Ryzen Mobile processors require that attackers first obtain administrative rights on a specific network or computer, which is an obstacle that is difficult but by no means impossible. remove. From there, the attackers can exploit the vulnerabilities to achieve a variety of extraordinary feats that would be catastrophic for the long-term safety of the owners. Among other things, exploits include:

  • Running persistent malware inside the secure AMD processor that is impossible or almost impossible to detect
  • Omit advanced protections such as AMD's encrypted secure virtualization, reliable platform firmware module and others security features, which are intended to protect systems and confidential data in case the malware infects a computer's operating system
  • Steal credentials that a vulnerable computer uses to access networks
  • Physical destruction of hardware by attackers in hardware-based "ransomware" scenarios [1
    9659007] "All these things are real"

    The four classes of vulnerabilities, called Masterkey, Ryzenfall, Fallout and Chimera, were described in a 20-page report entitled "Warning serious security in AMD processors. " The warning came with its own warning that CTS – the Israeli research organization that published the report – "may have, directly or indirectly, an economic interest in the performance" of the shares of AMD or other companies. It also reveals that its contents were all statements of opinion and "no statements of facts." Critics have said that the disclaimers, which are very unusual in security reports, are indications that the report is exaggerating the severity of the vulnerabilities in an obvious attempt to affect the price of AMD's shares and possibly other companies Critics also blamed investigators for giving AMD only 24 hours to review the report before it was made public and use a dedicated website to draw attention to the flaws.

    AMD officials issued a statement saying: "At AMD, safety is a top priority and we are continuously working to ensure the safety of our users as new risks arise." We are investigating this report, which we have just received. , to understand the methodology and the merit of the findings ".

    Still, Dan Guido, a chip security expert and the CEO of the security company Trail of Bits, told Ars that whatever the hidden motives they may have, the document accurately describes a threat real. After spending much of last week testing the proof-of-concept exploits discussed in the document, he said, he has determined that the vulnerabilities they exploit are real.

    "All exploits work as described," he said. "The package that I shared with me had well-documented and well-described reports for each individual error, they are not false, all these things are real, I'm trying to be a measured voice, I'm not exaggerating them, I will not rule them out."

    Once hackers get low-level access to a specific network, they usually gather as much data as possible in hopes of raising their privileges. All that is required to exploit the vulnerabilities of the AMD chip, said Guido, is a unique administrator credential within the network.

    "Once you have administrative rights, exploiting errors is unfortunately not that complicated," he said.

    Omitting the signature checks

    Although the AMD chips are supposed to require the firmware running on them to be digitally signed, Guido said the exploits massage the code in a way that allows the loaded firmware to pass the checks Validation without a valid signature. Once the malicious firmware of the attacker runs on the processor, it is almost impossible to detect using today's tools. In addition, the firmware has direct access to protected memory, hard drives, input / output devices and other computer components that may be beyond the reach of more traditional malware.

    "I ran the exploit code that allows me to get shells" Guido said. "They make a bad commitment much worse, there are no tools to help you find out if these problems have been exploited." The vulnerabilities, he said, are not related to a code execution flaw disclosed in January in AMD's trusted platform module.

    Not so fast

    Other researchers minimized the seriousness of the defects and questioned the veracity of the report, which was published on the same day that the short seller Viceroy Research issued a report that said AMD shares could lose everything its value. AMD's stock initially fell after the release of the reports, but eventually closed more. Critics of the report, meanwhile, said the requirement that an attacker already have administrative rights meant that the vulnerabilities were not as severe as described.

    "All exploits require root access," said David Kanter, a chip expert who is a founder of Real World Technologies. "If someone already has root access to their system, they are already compromised, which is like someone breaking into their house and getting video cameras installed to spy on them."

    Still, Kanter agreed with Guido that the vulnerabilities were a great shame for AMD, particularly because most of them reside in the Secure Platform Processor, which is the AMD version of the secure enclave on the iPhone. Unlike Apple, which designed its secure enclave, AMD relies on a 32-bit Cortex A5 processor designed by ARM.

      A basic description of the AMD Zen architecture that describes the secure processor.
    Enlarge / A basic overview of the Zen architecture of AMD that describes the secure processor.


    AMD's secure processor, said Guido, "is meant to be the defensible part of the processor." The fact that it can load an unsigned code and get to pass the validation and the fact that it can manipulate all mail slot handlers are not what you would expect as someone who needs to trust this component. "

    Other vulnerabilities were the result of what Tuesday's announcement said were" backdoors "of the manufacturer that were integrated into a chipset that connects the Ryzen and Ryzen Pro processors to hardware devices such as Wi-Fi chips and network cards. One of the rear doors is integrated into the firmware, according to the report, while the other resides in the hardware. AMD's partner for the chips, according to the report, is ASMedia. In 2016, ASMedia's parent company, ASUSTeK Computer, resolved the charges filed by the Federal Trade Commission alleging that it neglected security vulnerabilities. The agreement requires ASUSTek to undergo external security audits for 20 years.

    Tuesday's report went on to warn that Chimera's vulnerabilities resulting from the alleged backdoors may be impossible to solve.

    As explained above, the report's findings are highly nuanced because they are based on an already serious compromise that allows attackers to gain administrative control of a computer running one of the vulnerable AMD processors. That steep bar is counteracted by an achievement that is not possible with most exploits Specifically:

    • The ability to take complete control of the affected machine, including the parts that are normally isolated from the malware
    • The ability to execute malicious code before the operation the system boots and infections persist even after reinstalling the operating system
    • The ability to bypass advanced protections like Windows 10 Credential Guard

    People who trust AMD chips should not enter in panic, but neither should they discount the warnings contained in the report, despite the questionable motivations for its publication.

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