Security Software

More Information on PortSmash

On November 2nd, researchers from Tampere University of Technology in Finland and Technical University of Havana, Cuba published details and a proof of concept exploit they called “PortSmash.”

They demonstrate the creation of a side channel by taking advantage of resource contention from simultaneous multithreading (SMT), including our implementation, called Intel® Hyper Threading (Intel® HT). In SMT, different threads share some resources, including ports within the execution engine. A malicious actor can run code on one thread that will reveal timing measurements from the other thread. The differences observed in those measurements can reveal data over time.

Their proof of concept demonstrated that this side channel method could be used to disclose private keys from the OpenSSL cryptographic library—which has since been patched to address this issue.

After careful assessment, Intel determined that this method was similar to previously disclosed execution timing side channels and not a variation of speculative execution side channels such as Spectre, Meltdown, and L1TF. Existing programming best practices, such as employing constant execution timing and/or avoiding control flows that vary depending on secret data, can mitigate against PortSmash.

Intel does not recommend turning off Intel® HT as a mitigation technique because other programming methods are effective and higher performing.

Was this article helpful?YesNo
0% of users found this helpful

Intel technologies’ features and benefits depend on system configuration and may require enabled hardware, software, or service activation. Performance varies depending on system configuration. Check with your system manufacturer or retailer or learn more at

All information provided here is subject to change without notice. Contact your Intel representative to obtain the latest Intel product specifications and roadmaps.

Software and workloads used in performance tests may have been optimized for performance only on Intel microprocessors.

Performance tests, such as SYSmark and MobileMark, are measured using specific computer systems, components, software, operations and functions. Any change to any of those factors may cause the results to vary. You should consult other information and performance tests to assist you in fully evaluating your contemplated purchases, including the performance of that product when combined with other products. For more complete information visit

Performance results are based on testing as of dates shown in configurations and may not reflect all publicly available​ updates.

The products and services described may contain defects or errors known as errata which may cause deviations from published specifications. Current characterized errata are available on request.

Intel provides these materials as-is, with no express or implied warranties.

No product or component can be absolutely secure.

Your costs and results may vary.

© Intel Corporation.  Intel, the Intel logo, and other Intel marks are trademarks of Intel Corporation or its subsidiaries.  Other names and brands may be claimed as the property of others.