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Episode #877 Quiz

The Hertzbleed Attack
Date: 2022-06-28 | Length: 1.75 hrs | Episode page at twit.tv

About this episode

Hertzbleed exploits dynamic CPU frequency scaling as a remote timing side channel: data-dependent power use changes clock speed, revealing secret information even from constant-time cryptography. It affects Intel and AMD x86 processors, including SIKE implementations. Mitigations include disabling turbo/boost, though performance drops. No microcode fix exists, so software hardening is needed.

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Question 1: According to the episode, what made the Hertzbleed attack notable even against carefully written cryptographic code?

Question 1

According to the episode, what made the Hertzbleed attack notable even against carefully written cryptographic code?

It forced branch predictor state to leak secret-dependent cache contents. It depended on faulting arithmetic instructions to reveal intermediate key material. It turned CPU frequency changes into a remote timing side channel. It extracted keys by abusing a flaw in OpenSSL's handling of heartbeat packets.

Question 2: What mitigation did the episode say could reduce Hertzbleed, and why was it not generally recommended?

Question 2

What mitigation did the episode say could reduce Hertzbleed, and why was it not generally recommended?

Replace SIKE with a larger key size, because the attack only works on short keys. Disable frequency boost, because it significantly harms performance. Disable TLS session resumption, because the attack depends on repeated handshakes. Patch the affected CPUs with new microcode, because Intel and AMD planned to ship it.

Question 3: Which statement best matches the episode's description of SIKE in the context of Hertzbleed?

Question 3

Which statement best matches the episode's description of SIKE in the context of Hertzbleed?

It is a web authentication protocol used to replace passwords on browsers and phones. It is a symmetric cipher mode whose integrity check fails under double encryption. It is the OpenSSL module whose heartbeat extension was exploited in Heartbleed. It is a decade-old key encapsulation mechanism and NIST post-quantum finalist.

Question 4: What did the episode say about Intel and AMD's response to Hertzbleed?

Question 4

What did the episode say about Intel and AMD's response to Hertzbleed?

They provided software guidance, but no microcode patches were planned. They asked users to disable all TLS encryption until a firmware update ships. They planned microcode fixes, but only after an extended embargo period. They confirmed ARM processors were the only affected systems.

Question 5: Which combination of vulnerability categories did Forescout use to summarize the OT:ICEFALL findings?

Question 5

Which combination of vulnerability categories did Forescout use to summarize the OT:ICEFALL findings?

Buffer overflows, SQL injection, cross-site scripting, and format-string flaws. Insecure engineering protocols, weak cryptography, insecure firmware updates, and native RCE paths. Credential stuffing, ransomware delivery, lateral movement, and exfiltration tooling. Phishing kits, browser exploits, cloud misconfigurations, and stolen credentials.

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