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ngCERT-2019-0011: ngCERT Advisory on Intel-chips-vulnerability
Risk
Critical
Damage
High
Platform
Intel® CPUs
Advisory ID
ngCERT-2019-0011
Published Date
Wednesday 15th, May 2019
Summary
Millions of computers powered by Intel processors are affected by vulnerabilities that can be exploited by malicious actors to obtain potentially sensitive information. The side-channel attack methods, named ZombieLoad, Rogue In-Flight Data Load,(RIDL) and Fallout, are similar to the notorious Meltdown and Spectre. The attack methods work against both PCs and cloud environments, and they can be launched against most Intel CPUs.
Description and Consequences

The techniques can be used to get applications, the operating system, virtual machines and trusted execution environments to leak information, including passwords, website content, disk encryption keys and browser history. An attacker can perform an MDS-based attack from user space, with unprivileged instructions.  As the leakage occurs from stale data latched in buffers in the pipeline, the only defence is to flush the buffers before moving to a less privileged context. For example, hackers can use the ZombieLoad attack, which is a subclass of RIDL, to obtain a user’s browsing history even if the victim surfs the web from a virtual machine or uses the Tor anonymity network.

Solutions

Mitigation can be in a way of combination of software, firmware and configuration changes.  It is important to note that some affected processors are not expected to receive microcode updates.  For these processors, there is no mitigation available.  Users with workloads of concern on these processors should move the workload elsewhere. 

Solution for this issue if you have any untrusted code running in VMs, and need to prevent the risk of data leakage, the only available option at the moment is to disable hyper-threading.  This is preferably done in the BIOS, but can also be done by Xen at boot time by specifying `smt=no` on the command line. 

Warning

If you find that a computer is susceptible to ZombieLoad, you may want to avoid using it as a multi-user system. ZombieLoad breaches the CPU's memory protection. On a machine that is susceptible to ZombieLoad, one process can potentially read all data used by other processes or by the kernel.

Revisions

None