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Siemens SCALANCE W780 and W740

Monitor4.3ICS-CERT ICSA-21-040-07Feb 9, 2021
Attack VectorAdjacent
Auth RequiredNone
ComplexityLow
User InteractionNone needed
Summary

A resource exhaustion vulnerability exists in Siemens SCALANCE W780 and W740 wireless access points (IEEE 802.11n family) running firmware versions prior to 6.3. An attacker with wireless network access can send specially crafted network traffic to consume device memory or CPU resources, causing a denial of service condition that renders the device unresponsive. The vulnerability affects all versions below 6.3 and has potential for exploitation (CVSS 4.3, AV:A/AC:L/PR:N).

What this means
What could happen
A denial of service condition could occur on the SCALANCE W780 and W740 wireless access points, potentially interrupting network connectivity for field devices and remote access to control systems during critical operations.
Who's at risk
Water utilities and electric utilities using Siemens SCALANCE W780 or W740 wireless access points to connect field PLCs, RTUs, and remote telemetry devices should prioritize this issue. These devices are commonly deployed in distribution networks, substations, and treatment facilities where wireless connectivity enables remote monitoring and diagnostics.
How it could be exploited
An attacker with wireless network access to the device (within radio range) can send specially crafted network traffic to exhaust memory or processing resources, causing the device to become unresponsive. No authentication is required—the attack works against any device on the same wireless network segment.
Prerequisites
  • Wireless network access to the SCALANCE W780 or W740 (attacker within radio range of the device)
  • Device running firmware version prior to v6.3
  • No valid credentials required
remotely exploitable (via wireless)no authentication requiredlow complexity attackaffects network availability
Exploitability
Low exploit probability (EPSS 0.1%)
Affected products (1)
ProductAffected VersionsFix Status
SCALANCE W780 and W740 (IEEE 802.11n) family: All<V6.36.3
Remediation & Mitigation
0/3
Do now
0/1
WORKAROUNDDisable or restrict wireless access to SCALANCE W780 and W740 devices using firewall rules or access control lists; limit wireless network exposure to only authorized users and devices
Schedule — requires maintenance window
0/1

Patching may require device reboot — plan for process interruption

HOTFIXUpdate SCALANCE W780 and W740 devices to firmware version 6.3 or later
Long-term hardening
0/1
HARDENINGSegment wireless control system networks from business networks and the Internet; place wireless access points behind firewalls with strict ingress/egress filtering
View full CISA ICS-CERT advisory
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Siemens SCALANCE W780 and W740 | CVSS 4.3 - OTPulse