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Moxa Security Enhancement: SSL Medium Strength Cipher Suites Supported (SWEET32)

Act NowMPSA-251371Oct 9, 2025
Summary

DES and Triple DES ciphers, when used in TLS, SSH, and IPSec protocols, are vulnerable to birthday attacks that can decrypt long-duration encrypted sessions. The vulnerability, known as SWEET32 (CVE-2016-2183), allows remote attackers to recover plaintext data by exploiting the ~4 billion block birthday bound of these algorithms. Moxa devices supporting these weak cipher suites should be configured to disable them and enforce stronger encryption standards.

What this means
What could happen
An attacker with persistent network access to encrypted connections using weak cipher suites (DES/Triple DES) could potentially decrypt sensitive traffic over extended sessions, compromising credentials or configuration data transmitted to or from the Moxa device.
Who's at risk
Network administrators and plant operators of industrial communications equipment using Moxa devices for remote management, SCADA/HMI connectivity, or protocol gateway functions should review and disable weak encryption. This affects any organization using Moxa products (industrial Ethernet switches, industrial gateways, remote terminal units) where encrypted management or data tunnels rely on TLS, SSH, or IPSec protocols.
How it could be exploited
An attacker positioned on the network path to the Moxa device intercepts encrypted TLS/SSH/IPSec traffic using Triple DES or DES ciphers. Over a long-duration encrypted session (billions of blocks of data), the attacker performs a birthday attack to derive the encryption key and decrypt the session traffic. This requires no active compromise of the device itself, only the ability to observe and collect encrypted packets.
Prerequisites
  • Network access to intercept encrypted traffic between client and Moxa device
  • Client or Moxa device configured to accept DES or Triple DES cipher suites
  • Long-duration encrypted session (multiple hours/days of data transfer)
Remotely exploitableWeak default encryption configurationHigh EPSS score (41%)Affects confidentiality of management and operational dataNo vendor patch available
Exploitability
High exploit probability (EPSS 41.0%)
Affected products (1)
ProductAffected VersionsFix Status
Security Enhancement: SSL Medium Strength Cipher Suites Supported (SWEET32)All versionsNo fix (EOL)
Remediation & Mitigation
0/4
Do now
0/3
HARDENINGDisable DES and Triple DES cipher suites in TLS/SSH/IPSec configuration on all Moxa devices
HARDENINGEnforce minimum TLS 1.2 with strong cipher suites (AES-GCM or ChaCha20-Poly1305) for all management and data connections
WORKAROUNDMonitor TLS handshake logs to identify any active use of weak cipher suites and disable them at the device or firewall level
Schedule — requires maintenance window
0/1

Patching may require device reboot — plan for process interruption

HARDENINGReview and update any engineering workstations, HMI systems, or external connections to use only strong ciphers when communicating with Moxa devices
View full Moxa Security advisory
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Moxa Security Enhancement: SSL Medium Strength Cipher Suites Supported (SWEET32) - OTPulse