Security Experts:

AMD Chip Flaws Confirmed by More Researchers

Another cybersecurity firm has independently confirmed some of the AMD processor vulnerabilities discovered by Israel-based CTS Labs, but the controversial disclosure has not had a significant impact on the value of the chip giant’s stock.

CTS Labs last week published a brief description of 13 allegedly critical vulnerabilities and backdoors found in EPYC and Ryzen processors from AMD. The company says the flaws can be exploited for arbitrary code execution, bypassing security features (e.g. Windows Defender Credential Guard, Secure Boot), stealing data, helping malware become resilient against security products, and damaging hardware.

The flaws have been dubbed MASTERKEY, RYZENFALL, FALLOUT and CHIMERA, and exploiting them requires elevated privileges to the targeted machine — physical access is not required. The security firm will not disclose technical details any time soon in order to prevent abuse.

CTS Labs, which no one heard of until last week, came under fire shortly after its disclosure for giving AMD only a 24-hour notice before going public with its findings, and for apparently attempting to short AMD stock. The company later made some clarifications regarding the flaws and its disclosure method.

While initially many doubted CTS Labs’ claims due to the lack of technical information, an increasing number of independent researchers have confirmed that the vulnerabilities do in fact exist. Nevertheless, there are still many industry professionals who believe their severity has been greatly exaggerated.

Trail of Bits was the first to independently review the findings. The company, which has been paid for its services, has confirmed that the proof-of-concept (PoC) exploits developed by CTS Labs work as intended, but believes that there is “no immediate risk of exploitation of these vulnerabilities for most users.”

“Even if the full details were published today, attackers would need to invest significant development efforts to build attack tools that utilize these vulnerabilities. This level of effort is beyond the reach of most attackers,” Trail of Bits said in a blog post.

On Monday, Check Point also confirmed two of the RYZENFALL vulnerabilities following its own review. The security firm says it does not have any relationship with CTS Labs and it has not received any payment for its services. It also noted that it does not agree with the way CTS disclosed its findings, describing it as “very irresponsible.”

“In our opinion the original CTS Labs report might have been problematically phrased in a way that misrepresented the threat model and impact that the RYZENFALL-1 and RYZENFALL-3 vulnerabilities present,” Check Point said in a blog post. “However, problematic phrasing aside, after inspecting the technical details of the above, we can indeed verify that these are valid vulnerabilities and the risks they pose should be taken under consideration.”

Alex Ionescu, a reputable researcher and Windows security expert, also confirmed the findings and warned that “admin-level access and persistence are legitimate threats in multi-tenant IaaS and even things such as VTL0/1 (Credential Guard) when firmware and chipset trust boundaries are broken.”

AMD is investigating the claims, but it has yet to make any statement regarding the impact of the flaws.

Less than an hour after CTS Labs released its report, a controversial company named Viceroy Research published what it described as an “obituary” in hopes of leveraging the findings to short AMD stock. Since CTS’s report also included a disclaimer noting that the company had a financial interest, many assumed the two were working together to short AMD.

While CTS has avoided answering questions regarding its financial interests, Viceroy representatives told Vice’s Motherboard that the company obtained the report describing the vulnerabilities from an “anonymous tipster” and claimed to have no connection to the security firm.

Viceroy’s attempt has had an insignificant impact on AMD stock and experts doubt the situation will change. This is not actually surprising considering that Intel was hit the hardest by Meltdown and Spectre — critical vulnerabilities disclosed by reputable researchers — and still the impact on the company’s stock has been only minor and temporary.

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.