A team of computer science researchers has uncovered a line of attack that breaks all defenses and can affect computers globally, says ScienceDaily report. The new vulnerability breaks all Spectre defenses, meaning that billions of computers and other devices across the globe are just as vulnerable today as they were when Spectre was first announced.
The researchers, led by Ashish Venkat, William Wulf Career Enhancement Assistant Professor of Computer Science at UVA Engineering, found a whole new way for hackers to exploit something called a “micro-op cache,” which speeds up computing by storing simple commands and allowing the processor to fetch them quickly and early in the speculative execution process. Micro-op caches have been built into Intel computers manufactured since 2011.
A Spectre attack tricks the processor into executing instructions along the wrong path. Even though the processor recovers and correctly completes its task, hackers can access confidential data while the processor is heading the wrong way.
The team of researchers reported its discovery to international chip makers in April and will present the new challenge at a worldwide computing architecture conference in June.
As all current Spectre defenses protect the processor in a later stage of speculative execution, they are useless in the face of Venkat’s team’s new attacks. Two variants of the attacks the team discovered can steal speculatively accessed information from Intel and AMD processors.
Researchers named the vulnerability Spectre because the flaw was built into modern computer processors that get their speed from a technique called “speculative execution,” in which the processor predicts instructions it might end up executing and preps by following the predicted path to pull the instructions from memory.
Since Spectre was discovered, the world’s most talented computer scientists from industry and academia have worked on software patches and hardware defenses, confident they’ve been able to protect the most vulnerable points in the speculative execution process without slowing down computing speeds too much.
Venkat’s team discovered that hackers can steal data when a processor fetches commands from the micro-op cache.
Intel’s suggested defense against Spectre, which is called LFENCE, places sensitive code in a waiting area until the security checks are executed, and only then is the sensitive code allowed to execute. But it turns out the walls of this waiting area have ears, which our attack exploits. We show how an attacker can smuggle secrets through the micro-op cache by using it as a covert channel, reveals Venkat to ScienceDaily.
Venkat expects computer scientists in academia and industry to work quickly together, as they did with Spectre, to find solutions.
Balaji Subramanian 
Sahana A 
Divith Narendra