A common assumption is that internet-facing PLCs exist because operators knowingly accept the risk, but repeated findings around cellular modems point to a different governance failure where vendor-installed maintenance paths sit outside asset inventories, procurement records, and security assurance. For Singapore’s public sector and critical infrastructure operators, the practical response is to treat every remote support channel as a managed identity with an accountable owner, require independent validation of vendor connectivity before systems enter production and after every major maintenance activity, and make external attack surface verification a routine control rather than an annual compliance exercise because undocumented access paths invalidate otherwise sound network segmentation.
A common assumption is that internet-facing PLCs exist because operators knowingly accept the risk, but repeated findings around cellular modems point to a different governance failure where vendor-installed maintenance paths sit outside asset inventories, procurement records, and security assurance. For Singapore’s public sector and critical infrastructure operators, the practical response is to treat every remote support channel as a managed identity with an accountable owner, require independent validation of vendor connectivity before systems enter production and after every major maintenance activity, and make external attack surface verification a routine control rather than an annual compliance exercise because undocumented access paths invalidate otherwise sound network segmentation.