10   ASDUs mirrored by the Controlled Station

Created: 14 Jan 2025

Status: Approval (N/A)

Part: Part 5-7 (2013, Edition 1)

Links:

Page: 16 to 31

Clause: 7.3.1 to 7.3-15

Paragraph: -

Issue

The standard specifies that ASDUs sent by the Controlling Station are mirrored by the Controlled Station with Cause of Transmission 44, 45 or 46 in case of unsupported values in Data Unit Identifier.

This directive allows an attacker to mirror the ASDUs sent by the Controlling Station, while the Controlled Station could execute the request and send back the correct response

Proposal

In secure implementations the Controlled Station should not mirror received ASDUs in case of unsupported values in Data Unit Identifier instead should discard them without taking any further action.
In IEC 62351-5 the lack of response condition from the Controlled Station is already covered in the Controlling Station state machine by the Reply Timeout.

Discussion Created Status
In case the controlled station does not support the security extensions, it would be normal behaviour to respond with any of the cause of transmissions 44 to 46. Purely in the protocol, a man-in-the-middle attack can not be avoided. 14 Mar 25 Approval (N/A)
In case the controlled station does not support the security extensions, it would be normal behaviour to respond with any of the cause of transmissions 44 to 46. Purely in the protocol you cannot avoid this man-in-the-middle attack. 14 Mar 25 Discussion (red)
Moved for discussion. 14 Mar 25 Discussion (red)
Accepted 21 Feb 25 Accepted
Accepted 21 Feb 25 Accepted

 

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