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Comments on What does this suspicious URL structure do?
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What does this suspicious URL structure do?
I (well, my spam trap) received email that I know is a scam, but I'm trying to understand how it works. The message contains a URL of the following form:
https:/example.com:2096/?goto_app=SomethingWithoutAnExtension
The single / after the protocol is suspicious, and I assume the key to a redirect that would be unfortunate. But how does this work? What's going on here?
I wondered if everything between the first two slashes would be ignored (I've heard of an exploit that works that way), but if so, I'm not sure how the rest of this string could do anything. There's not another layer of path that could be a URL,[1] and the thing after goto_app doesn't end in .exe or the like. I don't know if port 2096 is special.
I'm not going to try it to find out, but I did try going to https:/mydomain.example (a domain I control, not literally "mydomain"), using one slash instead of two, and Brave took me to my site. I tried looking it up in the IETF URL spec (is that the right place?) but I didn't find the details I was looking for (or maybe I'm looking in the wrong place).
How should this URL be parsed? How does this presumed scam work?
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If the URL were instead
https:/example.com:2096/something.example?goto...then I would assume that everything up to the second slash is a decoy and it would take me tohtttps://something.example?.... But there aren't enough slashes in the suspicious URL I received. ↩︎
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It's not as complex as a clever URL trick: your would-be scammer is incompetent. Technically, this is a malformed URL and shouldn't parse at all. The relevant spec is RFC 3986 §3 — for this purpose, there must be a literal :// between the scheme and authority (domain).
However, entering this into a browser will actually take you to the URL as if there was a double slash there. This is a browser feature, intended to correct for user error in typing URLs into the address bar.
Likewise, the port number isn't relevant to the scam here: it just happens to be the port that the scammer is hosting this website on.
The query string is probably relevant to the scam, but only in that it sounds like it directs you to the "right" place. My best guess here is that following the link would take you to a phishing scam intended to get you to provide your credentials for some popular service or other.
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