Siemens SCALANCE W700
Plan Patch8.4ICS-CERT ICSA-23-320-05Nov 14, 2023
Attack VectorAdjacent
Auth RequiredLow
ComplexityLow
User InteractionRequired
Summary
The SCALANCE W700 series of industrial wireless access points and bridges are affected by Wi-Fi encryption bypass vulnerabilities known as "Framing Frames." These vulnerabilities could allow an attacker to decrypt Wi-Fi traffic, hijack user sessions, or launch denial-of-service attacks against devices on the wireless network. The vulnerability affects all firmware versions of the W721, W722, W734, W738, W748, W761, W774, W778, W786, W788, W1748, W1788 series and WAM/WUM family devices. Siemens has not released patches and recommends environmental and operational countermeasures instead.
What this means
What could happen
An attacker within Wi-Fi range could decrypt network traffic to and from the access point, potentially capturing engineering commands, credentials, or operator interactions, or could disrupt communications between industrial devices connected through the wireless network.
Who's at risk
Water authorities, municipal electric utilities, and other critical infrastructure operators that use Siemens SCALANCE W700 series wireless access points or bridges to connect field devices, RTUs, or HMIs to the control network. This includes all W721, W722, W734, W738, W748, W761, W774, W778, W786, W788, W1748, W1788 models and the WAM/WUM wireless access modules used in factory automation and process control networks.
How it could be exploited
An attacker within wireless range of a SCALANCE W700 device could exploit the Wi-Fi encryption bypass to decrypt traffic, intercept session credentials, or inject frames to cause a denial-of-service attack. No special credentials or authentication are required—the attacker only needs to be within Wi-Fi range and able to capture and manipulate wireless frames.
Prerequisites
- Attacker within Wi-Fi range of the SCALANCE W700 device
- Wireless network traffic to intercept or manipulate
- No authentication required
Remotely exploitable (within Wi-Fi range)No authentication requiredLow complexity attackNo patch available from vendorAffects industrial wireless networks connecting control devicesHigh likelihood of credential or command interception
Exploitability
Low exploit probability (EPSS 0.1%)
Affected products (36)
36 pending
ProductAffected VersionsFix Status
SCALANCE W721-1 RJ45All versionsNo fix yet
SCALANCE W722-1 RJ45All versionsNo fix yet
SCALANCE W734-1 RJ45All versionsNo fix yet
SCALANCE W734-1 RJ45 (USA)All versionsNo fix yet
SCALANCE W738-1 M12All versionsNo fix yet
Remediation & Mitigation
0/6
Do now
0/2HARDENINGSegment wireless networks from critical control devices using air-gap or wired connections for essential command and control traffic
WORKAROUNDImplement additional encryption layer (VPN or IPsec) between wireless clients and control network to protect against Wi-Fi decryption
Schedule — requires maintenance window
0/2Patching may require device reboot — plan for process interruption
HARDENINGDeploy wireless intrusion detection to monitor for unusual frame patterns or session hijacking attempts
HARDENINGReview Wi-Fi network design to minimize exposure of critical control traffic over SCALANCE W700 devices
Long-term hardening
0/2HARDENINGReduce wireless coverage footprint by positioning access points inside buildings rather than near perimeter to limit attacker range
HOTFIXMonitor Siemens security announcements for future firmware updates or security patches that may address this vulnerability
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