Vulnerability · Published Aug 19, 2021 · Assigned by mitre

CVE-2020-35685

Critical 9.1

In plain English

A critical-severity security flaw in the affected software. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 2.1% (higher than 81% of all known vulnerabilities).

Severity (CVSS NVD)9.1Critical

Exploit odds (30 days)2.1%top 18.7% of all CVEs

Exploited in the wildNo reportsnot in CISA KEV

Attack toolingNoneno public tooling known

Official description

An issue was discovered in HCC Nichestack 3.0. 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. (Proper ISN generation should aim to follow at least the specifications outlined in RFC 6528.)

Affected products (as reported)

Vendor	Product	Versions
n/a	n/a	n/a

References

https://www.hcc-embedded.com x_refsource_MISC
https://cert-portal.siemens.com/productcert/pdf/ssa-789208.pdf x_refsource_CONFIRM
https://www.forescout.com/blog/new-critical-operational-technology-vulnerabilities-found-on-nichestack/ x_refsource_MISC
VU#608209 third-party-advisory, x_refsource_CERT-VN