In SIMATIC MV400 family versions prior to v7.0.6, the ISN generator is initialized with a constant value and has constant increments. An attacker could predict and hijack TCP sessions.
https://www.tenable.com/cyber-exposure/2021-threat-landscape-retrospective
https://www.tenable.com/blog/numberjack-nine-vulnerabilities-across-multiple-open-source-tcpip-stacks
https://www.forescout.com/resources/numberjack-weak-isn-generation-in-embedded-tcpip-stacks/
https://www.cisa.gov/news-events/ics-advisories/icsa-21-042-01
https://cert-portal.siemens.com/productcert/pdf/ssa-599268.pdf
Source: Mitre, NVD
Published: 2021-03-10
Updated: 2023-10-10
Named Vulnerability: NUMBER:JACK
Base Score: 5
Vector: CVSS2#AV:N/AC:L/Au:N/C:N/I:P/A:N
Severity: Medium
Base Score: 7.5
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Severity: High
EPSS: 0.00379