Warning: Copy the PLC-program before deleting the PLC or use the original project (one that was not uploaded by a PLC) to update the web server’s user management and to download the changed configurationĪs a general security measure, Siemens strongly recommends protecting network access to devices with appropriate mechanisms. The PLC must be deleted and reconfigured with a new project.
If a new TIA-Portal version is not available, updating the web server’s user configuration is not effective. If unintentional, unauthenticated access is possible, the web server’s user configuration needs to be removed and reconfigured using TIA-Portal v16 Update 5 or later, or v17 Update 2 or later related ET200 CPUs and SIPLUS variants), validate web server permissions for unauthenticated users by directly accessing the web server in an unauthenticated manner. 
Whenever changes of the web server’s user configuration are performed with one of the affected versions for S7-1200 or S7-1500 CPUs (incl.Siemens has identified the following specific workarounds and mitigations users can apply to reduce the risk:
SIMATIC STEP 7 (TIA Portal) v17: Update to v17 Update 2 or later. SIMATIC STEP 7 (TIA Portal) v16: Update to v16 Update 5 or later. SIMATIC STEP 7 (TIA Portal) v15: Currently no fix is planned. Siemens recommends updating their software to the latest version: Siemens reported this vulnerability to CISA. CRITICAL INFRASTRUCTURE SECTORS: Multiple Sectors. A CVSS v3 base score of 6.4 has been calculated the CVSS vector string is ( AV:L/AC:H/PR:H/UI:R/S:C/C:H/I:L/A:L). The attacker needs to have direct access to the impacted web server.ĬVE-2021-42029 has been assigned to this vulnerability. SIMATIC STEP 7 (TIA Portal) v17: All versions prior to v17 Update 2ģ.2 VULNERABILITY OVERVIEW 3.2.1 IMPROPER ACCESS CONTROL CWE-284Īn attacker could achieve privilege escalation on the web server of certain devices due to an improper access control vulnerability in the engineering system software. SIMATIC STEP 7 (TIA Portal) v16: All versions prior to v16 Update 5. SIMATIC STEP 7 (TIA Portal) v15: All versions. The following Siemens products are affected: 
Successful exploitation of this vulnerability could allow an attacker to achieve privilege escalation on the web server of certain devices configured by SIMATIC STEP 7 (TIA Portal) due to incorrect handling of the webserver’s user management configuration during downloading.
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