A customer receives a link that starts with your real company domain. They open it, pass through your website, and arrive at a different site. If an outsider controls that final destination, your application may be lending its familiar address to a journey your business never approved.
An open redirect occurs when an application accepts an untrusted destination and sends the browser there without the intended restriction. An open redirect security assessment checks where that destination comes from, which redirects the business actually needs, and what an unauthorized destination could accomplish in the tested workflow.
Login return paths, invitation journeys, and campaign links are useful places to start. Their names alone do not establish a flaw. The assessment needs a reproducible route from attacker-controlled input to the browser’s final destination.
Separate an approved redirect from an open redirect
Redirects serve ordinary purposes: moving visitors to a new address, returning a customer to an order after sign-in, or opening an approved partner service. A fixed redirect from your old domain to your current domain is a different design from a parameter that accepts any external destination.
Write the intended rule for each feature. A sign-in return path may be limited to local application pages. A partner launch feature may need a small set of external destinations. A public link service might intentionally support broader navigation, which needs its own abuse controls and clear user expectations.
OWASP’s unvalidated redirect guidance explains how a trusted starting address can make a phishing journey appear credible. Keep that risk distinct from stronger claims: a redirect alone does not prove that an attacker can read your session or take over an account.
Map login return paths and customer-facing links
Inventory destinations supplied through links, forms, saved campaign settings, and integration configuration. For each route, record who chooses the destination and when the application validates it. Include any destination preserved across sign-in or account creation.
For an illustrative customer portal, trace a link from an invoice notification through authentication to the invoice page. Identify which component stores the return path and which component finally uses it. A validation check at the start is insufficient evidence if a later step replaces the destination.
Choose representative routes with the development team. Include older login pages and mobile browser journeys if customers use them. Record excluded identity-provider or partner systems explicitly; permission to assess your application does not automatically include a third party.
Validate the destination the browser will actually use
OWASP recommends server-side mappings from approved identifiers where practical. If a feature must accept URLs, use parsed URL components and an explicit destination policy. A text check that merely finds the company name somewhere in the supplied string does not establish the destination’s identity.
For local return paths, use the framework’s maintained local-URL validation facility and test how the redirect API interprets accepted input. For approved external links, define the scheme, host, port, and any necessary path restriction. Keep the value that is validated consistent with the value used for navigation.
In an authorized test, use an unrelated destination controlled by the assessment team. It should display a benign marker and collect no credentials. Record whether the application rejects the destination, falls back to a safe page, or sends the browser to the marker.
Follow the complete redirect chain
A journey may pass through several application routes before reaching its destination. Capture the sequence, including server responses and browser-side navigation. Retain the final address after the page settles, rather than judging only the first response.
Check each handoff against the agreed policy. An approved intermediate endpoint should not silently turn a restricted return path into unrestricted external navigation. If the product deliberately sends customers outside the application, verify that the displayed destination and user choice match the intended journey.
Use synthetic accounts for sign-in tests. Do not place real passwords, authorization codes, or tokens in a destination used for a demonstration. If the suspected impact involves an authentication protocol, agree a separate controlled test and establish the specific disclosure or account effect before reporting it as confirmed.
Write a finding that engineering can close
A useful finding identifies the entry route, destination input, missing restriction, redirect chain, and observed outcome. State any required user interaction or sign-in condition. Explain the business concern in terms of the actual feature, such as a misleading invoice journey.
Choose remediation that fits the function. A return-to-order feature may need only a validated local path. A partner launcher may work better with a server-owned destination identifier. Removing every redirect can break the customer journey while leaving the underlying validation design unresolved.
For the retest, repeat the controlled external destination and verify the final address. Then complete ordinary sign-in, invitation acceptance, or partner navigation. Include a missing destination and an invalid saved destination so the fallback behavior is understood.
Open redirect assessment FAQs
Does HTTPS prevent an open redirect? HTTPS protects each connection. It does not decide whether your application should send a customer to a particular destination.
Is every external link an open redirect? No. A visible link to another website and an application redirect have different behavior. The assessment examines the redirect’s input, intended policy, and actual destination.
Does an open redirect always mean account takeover? No. Report the demonstrated outcome. Account compromise or token disclosure requires evidence of an additional path and the conditions that make it work.
Bring your customer navigation flows to Ceron
Include login, recovery, invitation, and partner journeys when discussing application assessment scope with Ceron. Provide the approved destination rules and test accounts so the work can evaluate customer behavior beyond a public homepage. Ceron’s engagement guidance describes documented coverage, limitations, and evidence for verified findings.
Read the password reset review for recovery-specific questions and the SaaS invitation security guide for workspace onboarding. Plan an application assessment with Ceron. The invoice journey is illustrative and does not describe a Ceron customer incident.
