security
Attackers could extract data, even working from inside a guest VM
Researchers from Germany’s Helmholtz Center for Information Security have found processors made by China’s Loongson have leaky caches that attackers could use to seek specific data.Loongson has developed its own LoongArch instruction set architecture (ISA) that blends approaches used by MIPS and RISC-V.On a site called LoongLeakAttack.com, the researchers explain that they found the leaky cache using a fuzzer, then noticed that the LoongArch ISA manual mentions an instruction that leaves 32 bits of a memory register in an “uncertain” state.
“Our analysis reveals that under certain circumstances, the ‘uncertain’ data originates from the L1 data cache,” the four researchers wrote. “Since this cache is not isolated between applications, LoongLeak can leak data from other applications and the operating system. Even worse, an attacker can prime the CPU’s internal state to target the leakage to a specific cache set.”
In a paper [PDF] explaining their research, authors Lorenz Hetterich, Tristan Hornetz, Fabian Thomas, and Michael Schwarz share case studies that “include recovering full-disk AES keys from the kernel, partial root password hashes from user-space, and bypassing traditional software defenses such as ASLR and stack canaries, all within seconds.”In case that’s not scaring you enough, they also point out “LoongLeak can be exploited from unprivileged user space, containers, or virtual machines.” The flaw even means “LoongLeak can cross the virtual machine boundary and leak host data from inside a VM.”
