Moxa Switches Vulnerability Enables Unauthorized Access through Authentication Bypass

Moxa has released a critical security advisory addressing a severe vulnerability affecting multiple series of its industrial Ethernet switches.

Tracked as CVE-2024-12297, this flaw allows remote attackers to bypass authentication mechanisms, potentially granting unauthorized access to critical network infrastructure.

With a CVSS v4.0 score of 9.2, the vulnerability is classified as critical, urging immediate action from administrators managing operational technology (OT) environments.

Technical Analysis

The vulnerability stems from a flaw in the frontend authorization logic of the affected devices. Identified as CWE-656 (Reliance on Security Through Obscurity), the issue resides in how the switches verify user credentials.

While the devices employ both client-side and back-end server verification, the implementation contains weaknesses that attackers can exploit.

By leveraging these flaws, an unauthenticated attacker can execute password brute-forcing (CAPEC-49) to guess valid credentials or utilize MD5 collision attacks to forge authentication hashes.

Successful exploitation allows the attacker to bypass the login screen entirely, leading to full device compromise.

Given the role of these switches in industrial networks, such access could allow threat actors to disrupt operations, intercept traffic, or pivot to other critical assets within the OT network.

CVE ID	CVSS v4.0 Score	Vector	Impact
CVE-2024-12297	9.2 (Critical)	AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:L/SI:L/SA:L	Authentication Bypass, Unauthorized Access

The vulnerability impacts the TN-A and TN-G series of managed Ethernet switches.

Moxa has released specific patch versions to remediate the flaw. Note that patches must be obtained by contacting Moxa Technical Support directly.

Product Series	Affected Versions	Remediation (Patch Version)
TN-A Series (TN-4500A, TN-5500A)	Firmware v4.1 and earlier	Contact Support for v3.13.255
TN-G Series (TN-G4500, TN-G6500)	Firmware v5.5 and earlier	Contact Support for v5.5.255

Mitigation and Security Best Practices

For organizations unable to immediately apply the firmware updates, Moxa recommends a defense-in-depth approach to mitigate the risk of exploitation:

• Network Segmentation: Utilize VLANs and physical separation to isolate operational networks from enterprise traffic.
• Access Control: Implement Access Control Lists (ACLs) and firewalls to restrict device management interfaces to trusted IP addresses only.
• Disable Internet Exposure: Ensure these switches are not directly exposed to the public internet.
• VPN Usage: Mandate encrypted communication protocols (SSH, VPN) for all remote management tasks.
• Log Monitoring: Enable event logging and regularly audit trails for anomalies, specifically focusing on repeated failed login attempts or unauthorized access indicators.

Administrators are advised to apply the relevant patches immediately to prevent potential brute-force or hash collision attacks against their industrial infrastructure.

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