Vulnerability Description
An issue was discovered in Ethernut Nut/OS 5.1. The code that generates Initial Sequence Numbers (ISNs) for TCP connections derives the ISN from an insufficiently random source. As a result, an attacker may be able to determine the ISN of current and future TCP connections and either hijack existing ones or spoof future ones. While the ISN generator seems to adhere to RFC 793 (where a global 32-bit counter is incremented roughly every 4 microseconds), proper ISN generation should aim to follow at least the specifications outlined in RFC 6528.
CVSS Score
HIGH
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Ethernut | Nut\/Os | 5.1 |
Related Weaknesses (CWE)
References
- http://lists.egnite.de/mailman/listinfo/en-nut-announceNot Applicable
- http://www.ethernut.de/en/download/index.htmlRelease Notes
- https://www.cisa.gov/news-events/ics-advisories/icsa-21-042-01Third Party AdvisoryUS Government Resource
- https://www.forescout.com/resources/numberjack-weak-isn-generation-in-embedded-tExploitThird Party Advisory
- http://lists.egnite.de/mailman/listinfo/en-nut-announceNot Applicable
- http://www.ethernut.de/en/download/index.htmlRelease Notes
- https://www.cisa.gov/news-events/ics-advisories/icsa-21-042-01Third Party AdvisoryUS Government Resource
- https://www.forescout.com/resources/numberjack-weak-isn-generation-in-embedded-tExploitThird Party Advisory
FAQ
What is CVE-2020-27213?
CVE-2020-27213 is a vulnerability with a CVSS score of 7.5 (HIGH). An issue was discovered in Ethernut Nut/OS 5.1. The code that generates Initial Sequence Numbers (ISNs) for TCP connections derives the ISN from an insufficiently random source. As a result, an attack...
How severe is CVE-2020-27213?
CVE-2020-27213 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2020-27213?
Check the references section above for vendor advisories and patch information. Affected products include: Ethernut Nut\/Os.