How should teams reduce business email compromise risk in approval workflows?

Why BEC approval risk is really an identity problem

Approval workflows fail when the approver is treated as a trusted communication endpoint instead of a separate identity with a distinct decision step. For BEC, the danger is not only spoofed messages, it is also one actor or mailbox being able to originate, influence, and complete the same business action without an independent check.

That is why payment releases, vendor-bank changes, payroll changes, and sensitive account updates should require a separate verifier who is not operating from the same mailbox, thread, or delegated access path. If the approval can be satisfied by replying inside the same conversation, the workflow is easy to steer with impersonation, thread hijacking, or forwarding abuse.

Email Identity and BEC Guide is the right reference point when teams need to harden the approval path itself, not just the message channel.

Controls that reduce approval-path exposure

The strongest control pattern is out-of-band verification for high-impact requests, paired with explicit role separation. One person requests, a different person verifies, and the second step uses a channel the first actor cannot easily control, such as a known callback, a portal challenge, or a recorded approval held outside the email thread.

Explicit confirmation should be reserved for actions that change money movement, recipient details, mailbox rules, or account recovery settings. For lower-risk requests, lighter approval may be acceptable, but the workflow should still preserve traceability so reviewers can see who approved, from where, and on what evidence.

Mailbox and identity controls also matter because approval abuse often rides on legitimate access. A mailbox that can both request and approve, a delegated inbox with broad authority, or an overbroad automation account will collapse the control into a single compromised path even if the user logs in with strong authentication.

Microsoft verified publisher OAuth phishing 2022 illustrates how mailbox access can be gained through abuse of trusted application consent rather than password theft alone.

How to design workflows so BEC cannot reuse trust

Teams should design approvals around transaction risk, not org chart convenience. High-value approvals deserve step-up verification, approval thresholds, and segregation between requestor, approver, and payment executor so a compromised mailbox cannot carry the process from start to finish.

Workflow owners should also reduce dependency on free-text email instructions. Structured requests, pre-approved beneficiary records, and change windows make it harder for an attacker to improvise a convincing exception request and easier for reviewers to compare the request against expected patterns.

When the business process still requires email, the approval should be backed by policy that defines which requests are never approved in-thread, which require secondary confirmation, and which need escalation to finance or security before execution.

Arup deepfake fraud 2024 shows why the approval path itself must resist executive impersonation, not just fraudulent message content.

Risk and Threat Considerations

Approval workflows create concentrated blast radius because they sit at the point where trust becomes action. If an attacker can hijack a mailbox, spoof an approver, or exploit delegated access, the workflow can be turned into an authenticated-looking fraud path that moves money or changes sensitive records before anyone realises the request was false.

Failure mechanism: The attacker abuses a trusted channel, such as thread hijacking, forwarded mail, OAuth mailbox access, or social engineering, to make a malicious request look like a legitimate internal approval. The control fails when the same communication path also carries the approval decision.

Impact: Teams can release fraudulent payments, redirect invoices, alter payroll or banking details, and lose the evidence chain needed to prove who authorised the action. Recovery is harder when approvals are logged only as email replies and no separate verifier exists.

Practitioner Guidance

What to prioritise: Focus first on the approval steps that can cause immediate financial or account-change impact. If the workflow can move funds, change beneficiaries, or reset access, it needs a separate verification path before you tune lower-risk approvals.

Decision rule: If the request changes payment destination, bank details, recovery settings, or privileged access, require an out-of-band verifier and forbid same-thread approval. If the request is routine and low impact, keep the path lightweight but still retain immutable audit evidence.

What to verify: Check whether the approver is truly independent, whether delegated mailbox access can bypass the second check, and whether the workflow records an auditable decision separate from the original email conversation.

Practitioner takeaway: The control objective is not to make email “safer”, it is to prevent a single compromised identity path from both requesting and approving the same high-impact action.

Related resources from NHI Mgmt Group

• How should security teams reduce business email compromise risk beyond secure email gateways?
• How should security teams reduce vendor email compromise risk in finance workflows?
• How should security teams reduce the risk of business email compromise when attackers rely on impersonation and urgency rather than malware?
• How should security teams reduce the risk of business email compromise when messages contain no links or attachments?