What evidence do auditors commonly ask for on COS-08 Policies for data transmission?

Transmission policy naming the transfer channels and tools that may be used; Cross-reference from classification levels to the transmission protection required; Instructions for exchanging data with external parties, including removable media handling; Guidance issued to staff who routinely move data between organisations.

What is the most common gap auditors find on COS-08?

Policy addresses electronic mail but ignores the file transfer and collaboration tools staff actually use

BSI C5 (121-criteria catalogue) · C5: Communication Security

`COS-08` Policies for data transmission

Document and issue data transmission policies with technical and organisational measures protecting transferred data against interception, manipulation, copying, alteration, redirection and destruction, with the protection demanded tied to the information classification scheme.

Source: BSI C5 (121-criteria catalogue), COS-08. The statement above is our statement of the clause, read from the published text and cited so you can check it against the official text, not the instrument verbatim. Open BSI C5 (121-criteria catalogue) in the compliance library.

The edition of the catalogue is not stamped here; check the edition your attestation is issued against.

artefacts

held by a system

at each review

hard

to go live

Policy repository / GRC workspace

where the evidence lives

teal = a system already holds it · olive = produced at each review. To go live: easy when half or more of the artefacts are already held by a system, moderate from a quarter to a half, hard below a quarter.

These are the artefacts auditors commonly ask for on this requirement, our guidance rather than text from the standard. Your assessor decides what is sufficient in your context, and asks for samples across the period when a report covers one.

system holds itEvidence a system already holds

none for this control

periodic reviewEvidence produced at each review

none for this control

governing documentDocuments that govern the control

Transmission policy naming the transfer channels and tools that may be used · Policy repository / GRC workspace
Cross-reference from classification levels to the transmission protection required · Policy repository / GRC workspace
Instructions for exchanging data with external parties, including removable media handling · Policy repository / GRC workspace
Guidance issued to staff who routinely move data between organisations · Policy repository / GRC workspace

First move

No system holds this evidence for you: it is people and documents. Reminders and routing to the owner still save time. Put the document under version control with an owner and review date, and log each review as a record with reviewer and date.

Common gaps auditors find

Policy addresses electronic mail but ignores the file transfer and collaboration tools staff actually use
Protection applied uniformly with no regard to how the information was classified
Redirection and destruction risks unaddressed because the policy considers only eavesdropping

Do this for your whole sheet

Paste the rows you run your controls from and get this mapping for every control at once, with the periodic-review ones flagged and a first move per row. No account for the first run.

Build my evidence sheet

COS-07 Documentation of the network topology · CRY-01 Policy for the use of encryption procedures and key management