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Siemens SINEMA Remote Connect Server

Plan Patch7.5ICS-CERT ICSA-21-103-08Apr 13, 2021
Attack VectorNetwork
Auth RequiredNone
ComplexityLow
User InteractionNone needed
Summary

Two Denial-of-Service vulnerabilities exist in the underlying third-party XML parser used by SINEMA Remote Connect Server versions prior to 3.0. An attacker can trigger a crash by sending specially crafted XML requests to the service, rendering it unavailable for remote engineering access. The vulnerabilities stem from improper handling of XML input (CWE-772: Missing Release of Resource After Effective Lifetime Ends; CWE-835: Loop with Unreachable Exit Condition). No known public exploits are currently available.

What this means
What could happen
An attacker could crash the SINEMA Remote Connect Server by sending specially crafted XML requests, disrupting remote access capabilities for engineering and maintenance staff managing industrial control systems.
Who's at risk
Water authorities, electric utilities, and other critical infrastructure operators using SINEMA Remote Connect Server for remote engineering access to industrial control systems and PLCs. This affects any organization that provides remote maintenance or diagnostics capabilities to field technicians and engineers.
How it could be exploited
An attacker with network access to the SINEMA Remote Connect Server (typically port 443 or configured management port) sends malformed XML payloads to the underlying XML parser. The parser fails to properly handle the input, causing a denial of service that makes the remote connection service unavailable.
Prerequisites
  • Network access to SINEMA Remote Connect Server management interface
  • No authentication required to trigger the denial-of-service condition
remotely exploitableno authentication requiredlow complexityaffects remote access to operational systemslow EPSS score but denial-of-service impact on critical operations
Exploitability
Low exploit probability (EPSS 0.5%)
Affected products (1)
ProductAffected VersionsFix Status
SINEMA Remote Connect Server<V3.03.0
Remediation & Mitigation
0/4
Do now
0/1
WORKAROUNDRestrict network access to SINEMA Remote Connect Server to trusted engineering and authorized personnel only using firewall rules
Schedule — requires maintenance window
0/1

Patching may require device reboot — plan for process interruption

HOTFIXUpdate SINEMA Remote Connect Server to version 3.0 or later
Long-term hardening
0/2
HARDENINGPlace SINEMA Remote Connect Server and all remote access infrastructure behind a perimeter firewall, isolated from the business network
HARDENINGIf remote access is required outside your facility, use a VPN with current security updates and ensure the connected devices are patched and hardened
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Siemens SINEMA Remote Connect Server | CVSS 7.5 - OTPulse