Full Report
The NPort devices use Telnet as one of the network device management services. Telnet does not support the encryption of client-server communications, making it vulnerable to Man-in-the-Middle attacks.
Analysis Summary
# Vulnerability: Unencrypted Telnet Management on Moxa NPort Devices
## CVE Details
- CVE ID: CVE-2020-27184
- CVSS Score: 5.3 (Medium) based on the provided vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
- *Note: The summary text provided a vector that results in a $\approx 5.3$ score, though the article confusingly lists "CVSS v3.1 0.0" initially. We derive the practical score from the detailed breakdown.*
- CWE: Not explicitly listed, but relates to improper use of non-secure protocols (CWE-311 Missing Encryption of Sensitive Data is implied).
## Affected Systems
- Products: Moxa NPort IA5000A Series (including IA5150A, IA5250A, IA5450A variants and their -IEX, -T, -AI modifiers).
- Versions: All versions prior to the patched firmware discussed below.
- Configurations: Devices utilizing the default Telnet management service.
## Vulnerability Description
The affected Moxa NPort devices appear to utilize the Telnet protocol for network management, which transmits all data, including credentials and configuration details, in clear text. This lack of encryption makes the communication susceptible to passive eavesdropping and active Man-in-the-Middle (MitM) attacks if an attacker can intercept the network traffic between a management client and the NPort device.
## Exploitation
- Status: Unknown existence of exploit (Article states "Unknown").
- Complexity: High (Requires the attacker to successfully execute a MitM attack, which often presupposes network placement or specific network manipulation).
- Attack Vector: Network (Requires network access to TCP port 23).
## Impact
- Confidentiality: High (Credentials and sensitive configuration data can be stolen).
- Integrity: None (The primary focus is passive eavesdropping, not data modification within this specific vector description).
- Availability: None
## Remediation
### Patches
- **NPort IA5150A/IA5250A Series:** Firmware version 1.5 or higher disables Telnet by default.
- **NPort IA5450A Series:** Firmware version 2.0 or higher disables Telnet by default.
### Workarounds
1. **Disable Telnet Service:** The vendor advises disabling the Telnet service entirely via the device's Console Settings.
2. **Firewall Restriction:** Configure border firewalls or network controls to restrict TCP port 23 access *only* to absolutely authorized sources.
3. **Use VPN for Remote Access:** Implement a Virtual Private Network (VPN) for all remote access sessions to ensure traffic traversing untrusted networks is encrypted.
## Detection
- **Indicators of Compromise:** Monitoring for unexpected connections or authentication attempts targeting TCP port 23/TCP on the NPort devices.
- **Detection methods and tools:** Implement Network Intrusion Detection Systems (NIDS) configured to alert on clear-text management protocol usage within the specific network segments hosting the NPort devices.
## References
- Vendor Advisory: hxxps://www.moxa.com/en/support/product-support/security-advisory/nport-ia5000a-serial-device-servers-vulnerabilities
- Manual Reference (Console Settings): hxxps://www.moxa.com/getmedia/356a278c-1ef9-48a2-99fc-f3a091893cbd/moxa-nport-ia5000a-i-o-series-manual-v5.0.pdf#Console%20Settings