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Siemens SIMATIC CP (Update A)

Act Now8.8ICS-CERT ICSA-21-222-07Aug 10, 2021
Attack VectorNetwork
Auth RequiredLow
ComplexityLow
User InteractionNone needed
Summary

SIMATIC CP 1543-1 and CP 1545-1 devices contain vulnerabilities in the embedded ProFTPD server (CWE-125: out-of-bounds read, CWE-416: use-after-free). These flaws could allow a remote attacker to read sensitive information or execute arbitrary code if FTP is enabled and accessed with valid credentials. The vulnerabilities affect CP 1543-1 firmware versions prior to 3.0 and CP 1545-1 versions prior to 1.1. FTP is disabled by default, but if enabled for file management or remote access, the device becomes exploitable.

What this means
What could happen
An attacker with network access to the FTP service could read sensitive data or execute arbitrary code on the SIMATIC CP communication processor, potentially disrupting industrial network connectivity or modifying network traffic for connected PLCs and devices.
Who's at risk
This affects any organization using Siemens SIMATIC CP 1543-1 or CP 1545-1 communication processors in industrial networks. These are common in utilities, manufacturing, and critical infrastructure that rely on Siemens S7 communications. If FTP is enabled for remote firmware management or file transfer, the devices are at risk.
How it could be exploited
An attacker sends a specially crafted FTP command to the embedded ProFTPD server listening on port 21/TCP. If the FTP service is enabled and the attacker has at least one valid credential on the system, the ProFTPD vulnerability (CWE-125 or CWE-416) could be triggered to read memory or execute code on the CP module itself.
Prerequisites
  • Network access to port 21/TCP on the SIMATIC CP device
  • Embedded FTP server must be enabled (disabled by default)
  • Valid login credentials for FTP authentication
remotely exploitablehigh EPSS score (68.9%)requires authentication but default FTP may be weakaffects network connectivity for control systemsthird-party component vulnerability (ProFTPD)
Exploitability
High exploit probability (EPSS 68.9%)
Affected products (2)
2 with fix
ProductAffected VersionsFix Status
SIMATIC CP 1543-1 (incl. SIPLUS variants)<V3.03.0
SIMATIC CP 1545-1<V1.11.1
Remediation & Mitigation
0/5
Do now
0/2
WORKAROUNDDisable the embedded FTP server if not required for operations
WORKAROUNDRestrict network access to port 21/TCP to only trusted IP addresses using firewall rules
Schedule — requires maintenance window
0/2

Patching may require device reboot — plan for process interruption

SIMATIC CP 1545-1
HOTFIXUpdate SIMATIC CP 1545-1 to firmware version 1.1 or later
All products
HOTFIXUpdate SIMATIC CP 1543-1 to firmware version 3.0 or later
Long-term hardening
0/1
HARDENINGIsolate SIMATIC CP devices from the business network and Internet behind a firewall
View full CISA ICS-CERT advisory
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