Which vulnerability is associated with CPU speculative execution and can allow reading of restricted memory in affected processors?

Which vulnerability is associated with CPU speculative execution and can allow reading of restricted memory in affected processors?

• A. Meltdown Vulnerability
• B. Spectre Vulnerability
• C. Rowhammer
• D. USB BadUSB

Answer: (A)

Speculative execution side-channel weaknesses let an attacker infer data by observing microarchitectural state, such as cache contents, after the CPU speculatively executes instructions. Meltdown exploits this to break the memory isolation between user applications and the kernel, allowing reading of restricted memory on affected processors. In practice, when a process pokes at memory it shouldn’t access, speculative execution can pull kernel data into the cache; an attacker then reads that data by timing how long certain memory accesses take. This specific path—bypassing memory isolation to read privileged memory—is what defines Meltdown. Spectre is related to speculative execution but focuses on tricking legitimate code into leaking secrets across boundaries through speculative paths, not necessarily reading restricted memory directly. Rowhammer is a hardware memory vulnerability causing bit flips in DRAM by rapid access patterns, unrelated to CPU speculative execution. USB BadUSB involves compromised USB devices and firmware, also unrelated to speculative execution.

Speculative execution side-channel weaknesses let an attacker infer data by observing microarchitectural state, such as cache contents, after the CPU speculatively executes instructions. Meltdown exploits this to break the memory isolation between user applications and the kernel, allowing reading of restricted memory on affected processors. In practice, when a process pokes at memory it shouldn’t access, speculative execution can pull kernel data into the cache; an attacker then reads that data by timing how long certain memory accesses take. This specific path—bypassing memory isolation to read privileged memory—is what defines Meltdown.

Spectre is related to speculative execution but focuses on tricking legitimate code into leaking secrets across boundaries through speculative paths, not necessarily reading restricted memory directly. Rowhammer is a hardware memory vulnerability causing bit flips in DRAM by rapid access patterns, unrelated to CPU speculative execution. USB BadUSB involves compromised USB devices and firmware, also unrelated to speculative execution.