Full Report
A critical vulnerability in Modicon M221 PLC could allow attackers to intercept traffic by remotely changing IPv4 parameters
Analysis Summary
# Vulnerability: Remote Manipulation of IPv4 Parameters in Modicon M221 PLC
## CVE Details
- **CVE ID:** CVE-2018-7802
- **CVSS Score:** 9.8 (Critical)
- **CWE:** CWE-306 (Missing Authentication for Critical Function)
## Affected Systems
- **Products:** Schneider Electric Modicon M221 Logic Controllers
- **Versions:** All firmware versions prior to V1.6.2.0
- **Configurations:** Systems utilizing the EcoStruxure Machine Expert - Basic (formerly SoMachine Basic) programming software for configuration.
## Vulnerability Description
The vulnerability stems from an insecure implementation of the communication protocol used by the Modicon M221 PLC. The device fails to properly authenticate or restrict access to critical engineering functions. Specifically, the protocol allows a remote attacker to send unauthenticated commands to modify the device's network configuration, such as its IPv4 address, subnet mask, and gateway settings.
## Exploitation
- **Status:** PoC known/Publicly documented (No widespread exploitation in the wild reported at time of disclosure).
- **Complexity:** Low
- **Attack Vector:** Network
## Impact
- **Confidentiality:** High (Enables Machine-in-the-Middle (MitM) attacks to intercept sensitive traffic).
- **Integrity:** High (Allows unauthorized modification of network parameters and control logic).
- **Availability:** High (Loss of communication with the PLC or permanent disconnection from the industrial network).
## Remediation
### Patches
- **Firmware Update:** Upgrade Modicon M221 firmware to **v1.6.2.0** or later.
- **Software Update:** Use EcoStruxure Machine Expert - Basic **v1.2** or later to apply security enhancements.
### Workarounds
- **Network Segmentation:** Place the PLC behind a firewall and ensure it is not accessible from the internet or untrusted business networks.
- **Protocol Filtering:** Disable or restrict access to port 502 (Modbus) and the proprietary discovery ports at the network perimeter.
- **Physical Security:** Use the physical write-protection switch on the PLC (if available) to prevent unauthorized configuration changes.
## Detection
- **Indicators of Compromise:** Unexpected loss of connectivity to the PLC, unauthorized changes in IP address configuration, or unusual traffic originating from the PLC to unknown external IPs.
- **Detection methods and tools:**
- Monitor network traffic for unauthorized engineering-protocol packets directed at M221 devices.
- Use Industrial IDS/IPS signatures specifically tuned for Schneider Electric's proprietary protocols.
## References
- Schneider Electric Advisory: hxxps[://]www[.]se[.]com/ww/en/download/document/SEVD-2018-312-01/
- Kaspersky ICS CERT Analysis: hxxps[://]ics-cert[.]kaspersky[.]com/advisories/2018/11/23/critical-vulnerability-in-modicon-m221-plc/
- NVD Entry: hxxps[://]nvd[.]nist[.]gov/vuln/detail/CVE-2018-7802