What evidence do auditors commonly ask for on OIS-03 Interfaces and Dependencies?

Shared responsibility model or duty matrix splitting delivery tasks between provider and third parties; Service descriptions and contract clauses that fix cooperation duties for incidents and malfunctions; Change notifications issued to dependent organisations, with dates showing the lead time given; Joint escalation and contact directory used for reporting faults across organisational boundaries.

What is the most common gap auditors find on OIS-03?

Split of duties agreed internally but never shared with the counterpart organisation

BSI C5 (121-criteria catalogue) · C5: Organisation of Information Security

`OIS-03` Interfaces and Dependencies

Document and communicate the interfaces and dependencies between delivery activities run by the provider and those run by third parties, covering how vulnerabilities, security incidents and malfunctions are handled, and notify affected parties of changes early enough to react before the change takes effect.

Source: BSI C5 (121-criteria catalogue), OIS-03. 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

Vendor register / contract repository

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

Shared responsibility model or duty matrix splitting delivery tasks between provider and third parties · Vendor register / contract repository
Service descriptions and contract clauses that fix cooperation duties for incidents and malfunctions · Vendor register / contract repository
Change notifications issued to dependent organisations, with dates showing the lead time given · Vendor register / contract repository
Joint escalation and contact directory used for reporting faults across organisational boundaries · Vendor register / contract repository

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

Split of duties agreed internally but never shared with the counterpart organisation
Interface changes announced only after they were already live
No defined route for passing vulnerability information to jointly operated components
Documentation pitched too abstractly for the specialists expected to act on it

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

OIS-02 Information Security Policy · OIS-04 Segregation of Duties