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Avail.zone – Open Redirect / SSRF via website Parameter

EN easy bug bounty writeup Open RedirectSSRFparameter injectionURL manipulationphishingrecon
Original

A phishing/spam email promotes a 'free partnership tool' at start.avail.zone. The invite URL passes a domain through a query parameter — what does the server actually do with it? Investigate the request flow and find an abuse path that could turn this 'invite' into something nastier.

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enumeration

Step 2 · Fingerprint the Application's Response Behaviour

Objective: Determine whether the application reflects, fetches, or redirects to the value supplied in the `website` parameter.

Context: With the modified URL in hand, use your browser and Burp Suite (Proxy → Intercept or HTTP History) to capture the full request/response cycle when the page loads.

Progressive hints

Only reveal the ones you need. Claude tracks how many you used to calibrate the feedback.

Hint 1 — directional nudge

Open Burp Suite, enable the proxy, and visit the modified invite URL. Check both the initial response and any subsequent requests the browser or server makes.

Hint 2 — technique / vuln class

Look for three distinct behaviours: (1) the value appears in HTML/JS output (reflection), (2) the server issues an HTTP request to the supplied domain (SSRF), or (3) the browser is sent to the supplied domain (Open Redirect).

Hint 3 — near solution

In Burp's HTTP History, filter for requests going OUT from the server to external hosts, or look for a 3xx Location header pointing to your supplied domain. Also check the rendered page source for the raw domain string.

Ask the tutor

Chat with a spoiler-safe tutor for this step. It uses only this lab spec and gives the smallest useful nudge first.

Tell the tutor what you tried, where you got stuck, or paste the response/error you are seeing.

Your attempt

Spotted something to improve?

Polish the wording, sharpen a hint, add missing context, fix a payload — your version stays separate from the original and other learners can choose it.

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