ReviewHigh

CVE-2020-5953

SIMATIC Field PG M5, SIMATIC Field PG M6

A vulnerability exists in System Management Interrupt (SWSMI) handler of InsydeH2O UEFI Firmware code located in SWSMI handler that dereferences gRT (EFI_RUNTIME_SERVICES) pointer to call a GetVariable service, which is located outside of SMRAM. This can result in code execution in SMM (escalating privilege from ring 0 to ring -2).

CVSS
7.5
EPSS
0.28%
20.5% percentile
CISA KEV
Not listed
Published
2022.02.03
PRIORITY ASSESSMENT

Review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability0.28%
Technical severityCVSS 7.5

Vulnerability overview

A vulnerability exists in System Management Interrupt (SWSMI) handler of InsydeH2O UEFI Firmware code located in SWSMI handler that dereferences gRT (EFI_RUNTIME_SERVICES) pointer to call a GetVariable service, which is located outside of SMRAM. This can result in code execution in SMM (escalating privilege from ring 0 to ring -2).

Affected product and versions

Product
SIMATIC Field PG M5, SIMATIC Field PG M6
Affected versions
< V22.01.10, < V26.01.13, < V27.01.09, < V28.01.04, < V21.01.17, < V25.02.12, < V23.01.10, 5.12.09.0074, 5.23.04.0045, 5.23.45.0023, 5.33.15.0034, 5.34.03.0029, 5.42.03.0010
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that SIMATIC Field PG M5, SIMATIC Field PG M6 and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:H/A:H
CWE
Not available