CVE-2021-31894
Published: 13 July 2021
Summary
CVE-2021-31894 is a high-severity Incorrect Permission Assignment for Critical Resource (CWE-732) vulnerability in Siemens Sinamics Starter Firmware. Its CVSS base score is 8.8 (High).
Operationally, ranked at the 8.7th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2021-18769
Vulnerability details
A vulnerability has been identified in SIMATIC PCS 7 V8.2 and earlier (All versions), SIMATIC PCS 7 V9.X (All versions < V9.1 SP2), SIMATIC PDM (All versions < V9.2 SP2), SIMATIC STEP 7 V5.X (All versions < V5.7), SINAMICS STARTER…
more
(containing STEP 7 OEM version) (All versions < V5.4 SP2 HF1). A directory containing metafiles relevant to devices' configurations has write permissions. An attacker could leverage this vulnerability by changing the content of certain metafiles and subsequently manipulate parameters or behavior of devices that would be later configured by the affected software.
- CWE(s)
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Procedures support proper permission assignment for critical resources through documented controls.
Attribute management for resources provides a mechanism to assign and maintain correct permissions based on security labels.
Prevents overly permissive assignments to critical resources by limiting to task needs.
Training policy covers correct permission assignment, reducing the ability to exploit incorrect permission assignments for critical resources.
Training on permission management reduces incorrect permission assignments for critical resources.
Audit logs and logging tools are critical resources whose protection requires correct permission assignments to block unauthorized actions.
Assessments review permission assignments on critical resources to confirm correctness, mitigating exploitation via incorrect permissions.
Certification includes checking that permissions on critical resources are correctly assigned.