CVE intelligence and bounded remediation

CVE-2021-31894 — Siemens Simatic Pcs 7 Firmware security vulnerability

High CVSS 8.8

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 (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.

Severity
High
CVSS
8.8 (3.1)
Published
2021-07-13
CISA KEV
Not currently listed
Ecosystem
operating-system
Weaknesses
CWE-732

Affected products

  • siemens / simatic_pcs_7_firmware
  • siemens / simatic_pcs_7_firmware / 9.0
  • siemens / simatic_pdm_firmware
  • siemens / simatic_step_7_firmware
  • siemens / sinamics_starter_firmware
  • siemens / sinamics_starter_firmware / 5.4

Showing 6 representative product identities from 11 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Privilege escalation and unsafe privilege management

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Check exposure

  • Map service accounts, operating-system identities, roles, capabilities, impersonation, set-user transitions, and administrative helper paths.
  • Determine whether untrusted users or lower-privilege processes can reach the affected transition or modify inputs it trusts.
  • Review file, socket, registry, device, job, container, and cloud-role permissions used before and after privilege changes.

Remediate safely

  • Apply the supported fix and redesign privileged operations as a minimal, authenticated, allowlisted interface.
  • Drop privileges before processing untrusted input, verify the drop succeeds, and remove unnecessary roles, capabilities, and write permissions.
  • Validate ownership and permissions at time of use and add explicit lower-to-higher privilege boundary tests.

Authoritative sources

Complete CVE record and remediation plan

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