Vulnerability Monitor

The vendors, products, and vulnerabilities you care about

CVE-2020-35685

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.)

Security Impact Summary

This vulnerability carries a CRITICAL severity rating with a CVSS v3.1 score of 9.1, indicating it can be exploited remotely over the network with relatively low complexity without requiring user interaction and does not require pre-existing privileges . The vulnerability impacts confidentiality (data exposure), integrity (unauthorized modifications), for affected systems. Impacting 5 products from hcc-embedded, from siemens, from siemens and 2 others, organizations running these solutions should prioritize assessment and patching.

Historical Context

Reported in 2021, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.

Published

2021-08-19T12:15:08.217

Last Modified

2024-11-21T05:27:50.993

Status

Modified

Source

[email protected]

Severity

CVSSv3.1: 9.1 (CRITICAL)

CVSSv2 Vector

AV:N/AC:L/Au:N/C:P/I:P/A:N

Access Vector: NETWORK
Access Complexity: LOW
Authentication: NONE
Confidentiality Impact: PARTIAL
Integrity Impact: PARTIAL
Availability Impact: NONE

Exploitability Score

10.0

Impact Score

4.9

Weaknesses

Type: Primary
CWE-330

Affected Vendors & Products

Type	Vendor	Product	Version/Range	Vulnerable?
Application	hcc-embedded	nichestack	3.0	Yes
Operating System	siemens	sentron_3wa_com190_firmware	< 2.0.0	Yes
Hardware	siemens	sentron_3wa_com190	-	No
Operating System	siemens	sentron_3wl_com35_firmware	< 1.2.0	Yes
Hardware	siemens	sentron_3wl_com35	-	No

References

https://cert-portal.siemens.com/productcert/pdf/ssa-789208.pdf Mitigation, Third Party Advisory ([email protected])
https://www.forescout.com/blog/new-critical-operational-technology-vulnerabilities-found-on-nichestack/ Mitigation, Third Party Advisory ([email protected])
https://www.hcc-embedded.com Product ([email protected])
https://www.kb.cert.org/vuls/id/608209 Third Party Advisory, US Government Resource ([email protected])
https://cert-portal.siemens.com/productcert/pdf/ssa-789208.pdf Mitigation, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://www.forescout.com/blog/new-critical-operational-technology-vulnerabilities-found-on-nichestack/ Mitigation, Third Party Advisory (af854a3a-2127-422b-91ae-364da2661108)
https://www.hcc-embedded.com Product (af854a3a-2127-422b-91ae-364da2661108)
https://www.kb.cert.org/vuls/id/608209 Third Party Advisory, US Government Resource (af854a3a-2127-422b-91ae-364da2661108)

How SecUtils Interprets This CVE

SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For hcc-embedded's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.