CVE-2017-20235: ProSoft ICX35-HWC Auth Bypass Flaw

CVE-2017-20235 Overview

ProSoft Technology ICX35-HWC version 1.3 and prior cellular gateways contain an authentication bypass vulnerability in the web user interface that allows unauthenticated attackers to gain access to administrative functions without valid credentials. Attackers can bypass the authentication mechanism in affected firmware versions to obtain full administrative access to device configuration and settings.

Critical Impact

Unauthenticated remote attackers can gain complete administrative control over ICX35-HWC cellular gateways, potentially compromising critical industrial network infrastructure and connected operational technology systems.

Affected Products

• ProSoft Technology ICX35-HWC firmware version 1.3
• ProSoft Technology ICX35-HWC firmware versions prior to 1.3

Discovery Timeline

• 2026-04-03 - CVE CVE-2017-20235 published to NVD
• 2026-04-07 - Last updated in NVD database

Technical Details for CVE-2017-20235

Vulnerability Analysis

This vulnerability is classified under CWE-287 (Improper Authentication), indicating a fundamental flaw in how the ICX35-HWC cellular gateway validates user credentials. The authentication bypass allows attackers to circumvent the normal login process for the web-based management interface, granting them the same level of access as a legitimately authenticated administrator.

Cellular gateways like the ICX35-HWC are commonly deployed in industrial control system (ICS) and operational technology (OT) environments to provide remote connectivity for SCADA systems, PLCs, and other critical infrastructure components. An authentication bypass in such devices presents significant risks to industrial network security, as attackers could modify gateway configurations, intercept communications, or use the compromised device as a pivot point for deeper network intrusion.

Root Cause

The vulnerability stems from improper authentication implementation in the web user interface of the ICX35-HWC cellular gateway. The authentication mechanism fails to properly validate user credentials before granting access to administrative functions, allowing unauthenticated requests to reach protected resources that should require valid login credentials.

Attack Vector

The attack is network-based and can be executed remotely without any user interaction or prior authentication. An attacker with network access to the ICX35-HWC web management interface can exploit this vulnerability to:

1. Access the administrative web interface without providing valid credentials
2. View and modify device configuration settings
3. Potentially intercept or manipulate network traffic passing through the gateway
4. Disable security controls or create persistent backdoor access

The attack requires no complexity or special privileges, making it highly accessible to adversaries. Organizations with internet-exposed ICX35-HWC devices or those with inadequate network segmentation are at particular risk.

Detection Methods for CVE-2017-20235

Indicators of Compromise

• Unexpected administrative sessions or logins to ICX35-HWC devices without corresponding authentication events
• Configuration changes made to gateway settings without authorized user activity
• Anomalous network traffic patterns to/from the ICX35-HWC web management interface
• Multiple access attempts to administrative URLs from unknown or external IP addresses

Detection Strategies

• Monitor web server logs on ICX35-HWC devices for requests to administrative endpoints that bypass normal authentication flows
• Implement network intrusion detection rules to identify unauthenticated access attempts to ICX35-HWC management interfaces
• Deploy network traffic analysis to detect anomalous patterns indicative of exploitation attempts against cellular gateways
• Configure SIEM alerts for any configuration changes on ICX35-HWC devices that lack corresponding authenticated user sessions

Monitoring Recommendations

• Establish baseline behavior for ICX35-HWC device access patterns and alert on deviations
• Monitor firmware versions across all deployed ICX35-HWC devices to ensure vulnerable versions are identified
• Implement continuous network segmentation monitoring to ensure cellular gateways are properly isolated from untrusted networks

How to Mitigate CVE-2017-20235

Immediate Actions Required

• Update ICX35-HWC firmware to the latest patched version available from ProSoft Technology/Belden
• Isolate affected ICX35-HWC devices on segmented network zones with restricted access until patching is complete
• Review access logs for any signs of unauthorized access or configuration changes
• Implement network access controls (firewall rules, ACLs) to restrict access to the ICX35-HWC management interface to authorized IP addresses only

Patch Information

ProSoft Technology (a Belden brand) has released a security bulletin addressing this authentication bypass vulnerability. Organizations should consult the Belden Security Bulletin for official patch information and firmware update instructions. Additional technical details are available in the VulnCheck Advisory.

Workarounds

• Restrict network access to the ICX35-HWC web management interface using firewalls or access control lists
• Disable remote management access if not required for operational purposes
• Implement VPN or jump host requirements for any remote administrative access to cellular gateway devices
• Deploy additional authentication layers such as network-level authentication before the device management interface

# Example: Restrict access to ICX35-HWC management interface (firewall rule)
# Only allow management access from trusted administrative subnet
iptables -A INPUT -p tcp --dport 80 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP