File sharing services

Sharing services fall into five groups, from governed enterprise platforms to one-off transfers that are effectively anonymous. Unlike a direct file transfer, sharing keeps the file in place and gives others access to it.

The most common exposure is not an exotic service but a personal account on a familiar one. Two accounts on the same device look identical to the user, and a file dragged into the wrong synced folder can leave the organization silently.

Sanctioned and unsanctioned use share the same domains and protocols. Telling them apart takes identity-aware inspection or endpoint visibility, because a domain block cannot separate the corporate tenant from the personal one. The same pattern appears with Shadow AI, where unapproved AI tools receive company content.

Shared links carry five recurring weaknesses:

• Access detached from identity: anyone holding the link can usually open the file.
• Onward forwarding: links pasted into messages spread access beyond the original audience.
• Persistence: links that never expire keep working after the business reason ends.
• Over-broad permissions: link editing is one click from organization-wide access, which can turn a small share into a data leak.
• Weak audit: external recipients are often unauthenticated, so the log shows no person.

Effective policy is granular rather than absolute. Typical measures are to sanction specific platforms and configure them properly, instead of prohibiting sharing in general, and to restrict sync clients to corporate tenants so personal accounts cannot mount on managed devices.

Discovery comes first, because enforcement only covers what is known. Start with discovery of the services already in use.

1. 1

   Find active shares

   List the sharing services and external links already in use. Most organizations underestimate how many there are.

2. 2

   Sanction and configure platforms

   Approve specific services and configure each one properly instead of banning sharing in general.

3. 3

   Restrict sync clients

   Allow them only for corporate tenants so personal accounts cannot mount on managed devices.

4. 4

   Require expiry and authentication

   Set expiry and authentication on external links, and limit public sharing to a small approved set of content.

5. 5

   Inspect uploads, revoke dormant shares

   Inspect uploads by content so regulated material stops before it leaves, and revoke dormant shares on a schedule.

Sharing decides where data resides and who processes it. That brings in data protection duties directly: a lawful basis and transfer rules for personal data under GDPR, retention requirements, and the ability to answer access and deletion requests for content held on a third-party platform.

A personal account holding customer records is a processing arrangement nobody has assessed. That is why unsanctioned sharing is treated as a compliance finding, not only a security one.

In cloud storage monitoring, the cloud storages control table sets access, audit, and shadow copy for each service. A separate list covers the web versions of the same services.

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Start with the sharing services already used on managed devices, then decide which ones are sanctioned and set the rules in Anexet DLP. A policy that blocks every link at once tends to push people into personal accounts, which brings the same risk back.

Keep the list of approved platforms short, and review it as the business changes.

Further reading: Prevention of data leaks by superuser.