CVE-2017-20234: GarrettCom Switch Auth Bypass Flaw

CVE-2017-20234 Overview

CVE-2017-20234 is an authentication bypass vulnerability affecting GarrettCom Magnum 6K and 10K managed switches. The vulnerability exists due to a hardcoded string in the authentication mechanism that allows unauthenticated attackers to bypass login controls and gain unauthorized access to administrative functions and sensitive switch configuration without valid credentials.

This vulnerability is classified under CWE-798 (Use of Hard-coded Credentials), which represents a severe security flaw where authentication secrets are embedded directly in code or firmware. Attackers who discover or reverse-engineer the hardcoded string can bypass normal authentication entirely.

Critical Impact

Unauthenticated remote attackers can gain full administrative access to affected network switches, potentially compromising network infrastructure, intercepting traffic, or disrupting operations.

Affected Products

• GarrettCom Magnum 6K managed switches
• GarrettCom Magnum 10K managed switches
• GarrettCom MNS-6K and MNS-10K series devices

Discovery Timeline

• 2026-04-03 - CVE-2017-20234 published to NVD
• 2026-04-07 - Last updated in NVD database

Technical Details for CVE-2017-20234

Vulnerability Analysis

The authentication bypass vulnerability in GarrettCom Magnum 6K and 10K switches stems from a hardcoded string embedded within the authentication mechanism. This fundamental security flaw allows attackers to circumvent the normal authentication process entirely without requiring knowledge of valid user credentials.

The vulnerability is network-exploitable with low attack complexity, requiring no privileges or user interaction, making it highly accessible to remote attackers. Successful exploitation results in complete compromise of confidentiality, integrity, and availability of the affected device.

Industrial network switches like the Magnum series are commonly deployed in critical infrastructure environments including manufacturing, utilities, and transportation systems. Compromise of these devices could enable attackers to perform man-in-the-middle attacks, manipulate network traffic, disrupt operations, or pivot to other systems on the network.

Root Cause

The root cause of CVE-2017-20234 is the use of hard-coded credentials (CWE-798) in the authentication subsystem. Developers embedded a static authentication string directly into the firmware rather than implementing proper credential management. This hardcoded value acts as a backdoor that bypasses normal authentication checks when provided by an attacker.

Hard-coded credentials are particularly problematic because they cannot be changed by end users without firmware updates, remain constant across all deployed devices of the same model, and may be discovered through firmware analysis or reverse engineering.

Attack Vector

The attack vector for this vulnerability is network-based, allowing remote exploitation without authentication. An attacker can target the management interface of affected GarrettCom switches to exploit the hardcoded authentication bypass.

The exploitation process involves identifying vulnerable GarrettCom Magnum 6K or 10K switches on the network, connecting to the management interface (typically web-based or CLI), and supplying the hardcoded authentication string to bypass login controls. Once authenticated, the attacker gains full administrative access to the switch configuration.

For detailed technical information on the vulnerability mechanism, refer to the Belden Security Bulletin and VulnCheck Advisory.

Detection Methods for CVE-2017-20234

Indicators of Compromise

• Unexpected administrative sessions on GarrettCom switch management interfaces
• Authentication events from unknown or unauthorized IP addresses
• Configuration changes made outside of normal change windows
• New user accounts or modified access permissions on affected devices
• Unusual network traffic patterns indicating reconnaissance or lateral movement

Detection Strategies

• Monitor authentication logs on affected switches for successful logins without corresponding legitimate user activity
• Implement network intrusion detection signatures for exploitation attempts targeting the hardcoded authentication bypass
• Deploy network traffic analysis to identify unauthorized access to switch management interfaces
• Audit configuration snapshots regularly to detect unauthorized modifications

Monitoring Recommendations

• Enable comprehensive logging on all GarrettCom Magnum 6K and 10K devices
• Forward switch logs to a centralized SIEM for correlation and alerting
• Monitor network segments for unauthorized access to management interfaces
• Implement alerting for any administrative access outside of approved maintenance windows

How to Mitigate CVE-2017-20234

Immediate Actions Required

• Identify all GarrettCom Magnum 6K and 10K switches in your environment
• Isolate management interfaces from untrusted networks using network segmentation
• Restrict access to switch management interfaces via firewall rules or access control lists
• Apply vendor-supplied firmware updates that address the vulnerability
• Monitor affected devices for signs of compromise

Patch Information

Belden (the parent company of GarrettCom) has released security information addressing this vulnerability. Organizations should consult the Belden Security Bulletin BSECV-2017-08 for specific firmware versions that remediate this issue and follow vendor guidance for applying updates to affected devices.

Workarounds

• Implement strict network segmentation to isolate switch management interfaces from general network access
• Deploy firewall rules restricting management interface access to specific trusted administrator IP addresses
• Use a dedicated out-of-band management network for critical infrastructure devices
• Enable multi-factor authentication if supported by the device or through a network access control solution

# Example: Network access control list to restrict management access
# Apply to upstream router/firewall protecting management VLAN
ip access-list extended RESTRICT-MGMT-ACCESS
  permit tcp host 10.1.1.100 host 192.168.100.10 eq 443
  permit tcp host 10.1.1.101 host 192.168.100.10 eq 22
  deny ip any host 192.168.100.10 log
  permit ip any any