The Third-Party Access Problem Hiding in Your SaaS Stack

We walk financial services organizations through their OAuth app inventory at least twice a month. It usually goes like this: they use our Free App Risk Assessment tool, are shocked by the risk scores of apps they thought were secure, then they need to do a review of everything in their environment. 

These teams typically expect to see a few dozen vetted apps across Google Workspace, Microsoft 365, and Salesforce. What the assessment reveals, instead, is a list of hundreds of OAuth-connected SaaS apps and extensions with access to their most critical environments–and the majority of which security and risk teams have never formally reviewed.

In financial services, where regulated data and strict compliance are central, seeing that many unvetted integrations touching email, files, and CRM data is often a genuine “how did this happen under our radar?” moment.

The Wake-Up Call

The classic pattern looks harmless on the surface: a small productivity or sales tool used by a relationship management team for email templating, open tracking, or light sequencing.

The business thinks they approved “send on my behalf” and basic contact sync, limited to a few users.

When we run the OAuth inventory, the actual picture is very different. The app has been granted broad scopes to read, send, and delete Gmail or Exchange messages, list and read files across users’ Google Drive or OneDrive, and access Salesforce data via connected app permissions.

It also holds long-lived tokens for dozens of users, including people in wealth management and corporate banking. That means it can continuously see sensitive client communications and documents without any further user interaction.

For the CISO and risk team, the disconnect is stark. On the business side, this is a “nice-to-have” email helper. In reality, the permission set makes it a de facto super-user service running in the background, with the ability to exfiltrate or manipulate regulated financial data across mail, files, and CRM.

No one had run a formal third-party risk review. There was no DPA on file. The app had been installed via user consent—outside the normal vendor process—then quietly propagated to more users over time.

Why User Consent Becomes Your Default Onboarding Process

Most financial services leaders assume that anything connecting to Google Workspace, Microsoft 365, or Salesforce must pass through procurement, security, and legal.

The tenant is often configured so that non-privileged users can consent to many app permissions by default. In Google Workspace, app access controls and OAuth settings were never tightened, so users can “Sign in with Google” and authorize third-party apps unless an admin has explicitly restricted those scopes or apps.

That gap between mental model (“we tightly control vendors”) and tenant reality (“we allow broad user consent except for a few restricted scopes”) is why user consent by default persists in highly regulated environments.

Three drivers emerge behind that misconfiguration:

• Structural defaults in the platforms. Both Google Workspace and Microsoft 365 historically leaned toward enabling productivity and ecosystem growth, so the out-of-the-box posture favors user consent with relatively light friction.
• Slow or opaque procurement paths. Business units experience vendor review as slow and unpredictable—weeks of questionnaires and contracts for what feels like a simple SaaS tool. Users default to “I’ll just click consent” to meet short-term goals.
• Visibility gaps between IT and the business. IT and security typically don’t have continuous discovery of OAuth grants, so they underestimate both the volume and importance of “small” tools in real workflows.

When Shadow IT Moves to Personal Accounts

The tell-tale sign of a problem isn’t just more Shadow IT. It’s a fundamental change in where and how the shadow apps are showing up.

You start to see sensitive workflows moving onto personal accounts and third-party channels that sit completely outside your controls. Client documents and deal materials risk being shared via personal Gmail, personal cloud storage, or personal messaging apps instead of the bank’s approved channels.

On the AI side, analysts, traders, or relationship management teams may be using personal ChatGPT or other AI subscriptions—tied to personal email and credit cards—to analyze transaction data, draft client communications, or summarize internal decks. They’re often pasting in non-public financial information.

When financial firms discover this is happening, the first conversations fixate on regulatory exposure: unarchived “communications,” unapproved third-party processing, and potential violations of record-keeping, privacy, and data-handling rules.

Once the dust settles, the conversation shifts to something broader: loss of visibility and defensibility.

If regulators ask, “Where is this class of data processed, and under what controls?” Shadow AI prompts in personal accounts are, by definition, off the books and hard to reconstruct.

What Auditors Actually Look For

Auditors and regulators are fundamentally looking for proof that third-party access is known, justified, limited, and monitored over time—not just a one-time vendor list.

For OAuth apps and browser extensions, “good” looks like a living, evidence-backed control set across inventory, risk, access, and audit trail.

When examiners dig into third-party and SaaS access, they look for whether you can demonstrate:

• Complete inventory and ownership. A current register of all OAuth apps and high-impact browser extensions across Google Workspace, Microsoft 365, Salesforce and other core systems, including who owns each integration, what data it can access, and why it exists.
• Risk-based due diligence and approvals. Documented risk assessments and approvals for higher-risk apps, tied to the permissions actually granted in your tenant—not just contract boilerplate.
• Principle of least privilege. Evidence that scopes and extension permissions are restricted to what’s necessary, that over-privileged apps are remediated, and that user consent is controlled via formal app-consent policies and admin workflows.
• Ongoing monitoring and review. Regular reviews of OAuth grants and extension usage, revocation of unused or high-risk apps, and continuous monitoring for anomalous behavior with defined response playbooks.
• Audit trails. Logs showing who authorized each app, what data and APIs it accessed, and what actions were taken when risks were identified.

The First 90 Days

The biggest obstacle to building that audit-ready posture isn’t technical. It’s structural.

The information you need lives in different silos, owned by different teams, with no one clearly accountable for stitching it together into a single view per app.

Identity and scope data lives in Google Workspace, Entra, or Salesforce admin consoles and security tools. Vendor due diligence and contracts live with procurement, legal, or third-party risk. Business context and ownership live with line-of-business leaders. Monitoring and incidents live with security operations.

When a regulator asks for evidence on a specific app, the organization has to manually reconcile admin portals, spreadsheets, ticketing systems, and legal files to assemble the story.

The first real lift is creating an explicit SaaS/OAuth governance function—often anchored in security or enterprise risk—and a single system of record that automatically pulls in identity, risk, and vendor data so every app can be treated as a first-class, managed asset.

The clearest proof point in the first 90 days is going from guesses to a defensible, risk-tiered inventory with actions attached:

1. A unified catalog of OAuth apps and high-impact extensions across all platforms, automatically populated and enriched with risk scores.
2. Each app assigned a business owner and risk tier with at least basic context: what it does, what data it touches, and why it’s allowed.
3. At least one closed loop of remediation: all unused or clearly high-risk apps above an agreed threshold have had tokens revoked or usage constrained, with an auditable record of those actions.

If, after 90 days, you can pull up a dashboard and answer “How many SaaS/OAuth apps do we have, how many are high-risk, who owns them, and what have we done about the worst ones?” with data instead of anecdotes, the governance function is taking root.

The Core Shift

Treat third-party SaaS, OAuth apps, and AI tools as an extension of your identity and data layer—not as “extra vendors.”

Make continuous, risk-tiered visibility into that layer a core control, on par with access management and logging.

Once you see every OAuth app and extension as another identity with real permissions to your crown-jewel data, the problem stops being “too many tools” and becomes “too many unmanaged access paths.”

That mindset pushes you to build a living system of record, risk-based policies, and a sanctioned fast lane for safe tools—so the fastest way to do high-stakes work becomes the most governed path, not the least.

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