Full Report
Weak implementation of cryptographic data protection allows various types of attacks and enables attackers to identify the key in captured traffic
Analysis Summary
Based on the analysis of the vulnerability research regarding the Modicon M100/M200/M221 series, here is the structured summary.
# Vulnerability: Weak Cryptography in Schneider Electric Modicon M100/M200/M221
## CVE Details
* **CVE ID:** CVE-2020-7524
* **CVSS Score:** 8.1 (High)
* **CWE:** CWE-327 (Use of a Broken or Risky Cryptographic Algorithm), CWE-330 (Use of Insufficiently Random Values)
## Affected Systems
* **Products:** Schneider Electric Modicon M100, M200, and M221 Logic Controllers.
* **Versions:** All versions prior to firmware v1.1.0.1.
* **Configurations:** Systems using the EcoStruxure Machine Expert - Basic (formerly SoMachine Basic) for configuration and password-based data protection.
## Vulnerability Description
The vulnerability stems from a weak implementation of cryptographic protocols used to protect sensitive data and communication between the engineering workstation and the PLC. Specifically, the implementation uses a **broken hashing algorithm** and a **predictable salt/nonce generation process**.
The device employs a proprietary "authentication" mechanism that relies on a fixed transformation of the password. Because the entropy is insufficient and the cryptographic primitives are outdated or improperly implemented, an attacker who captures network traffic can use offline brute-force or pre-computed tables to recover the original password/key.
## Exploitation
* **Status:** PoC available (Techniques documented by researchers; no widespread active exploitation reported in the wild at the time of publication).
* **Complexity:** Medium (Requires interception of network traffic/Packet Capture).
* **Attack Vector:** Network (The attacker must be able to sniff the traffic between the configuration software and the PLC).
## Impact
* **Confidentiality:** **Total** (Attackers can identify the session key and decrypt traffic, leading to the exposure of project files and passwords).
* **Integrity:** **High** (With the recovered key, an attacker can modify the controller's logic or parameters).
* **Availability:** **High** (Unauthorized access allows for stopping the PLC or changing operational states).
## Remediation
### Patches
* **Modicon M221:** Update to Firmware **v1.1.0.1** or later.
* **Software:** Update to **EcoStruxure Machine Expert - Basic v1.1** or later.
### Workarounds
* Ensure the PLC network is physically or logically isolated from the corporate/public internet.
* Use secure communication tunnels (e.g., VPN) if remote access is required, to prevent packet sniffing.
* Disable unused protocols and ports on the controller.
## Detection
* **Indicators of Compromise:** Unusual configuration upload/download requests from unauthorized IP addresses.
* **Detection methods:** Use Industrial Control System (ICS) monitoring tools to inspect Modbus/TCP traffic for anomalies. Monitor for unauthorized access to port 502 or the proprietary configuration ports.
## References
* Schneider Electric Security Advisory (SEVD-2020-196-01): hxxps[://]www[.]se[.]com/ww/en/download/document/SEVD-2020-196-01/
* Kaspersky ICS CERT Analysis: hxxps[://]ics-cert[.]kaspersky[.]com/publications/reports/2021/01/28/cryptographic-deadly-sins-and-the-security-of-modicon-m100-m200-m221/
* NIST NVD: hxxps[://]nvd[.]nist[.]gov/vuln/detail/CVE-2020-7524