VulnerabilityModified
CVE-2020-27632
An attacker could predict and hijack TCP sessions.
HIGH 7.5EPSS 1.21%
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (1.21%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
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.
- CVSS 3.1
- 7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
- EPSS
- 1.21% probability · 67th percentile
- CISA KEV
- Not listed
- Affected
- siemens/simatic mv420 firmware · siemens/simatic mv440 firmware
- Source
- cve@mitre.org
References
- https://cert-portal.siemens.com/productcert/pdf/ssa-599268.pdfVendor Advisory
- https://www.cisa.gov/news-events/ics-advisories/icsa-21-042-01
- https://www.forescout.com/resources/numberjack-weak-isn-generation-in-embedded-tcpip-stacks/
- https://cert-portal.siemens.com/productcert/pdf/ssa-599268.pdfVendor Advisory
- https://www.cisa.gov/news-events/ics-advisories/icsa-21-042-01
- https://www.forescout.com/resources/numberjack-weak-isn-generation-in-embedded-tcpip-stacks/
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.