Here is the question.
Given the url http://www.example.com, can we read the first N bytes out of the page?
You should also be aware that many HTTP/1.1 servers do not have this feature enabled, so that when you attempt to get a range, you'll instead get the whole document.
Last time I tried this technique it failed because it was actually impossible to read from the HTTP server only specified amount of data, i.e. you implicitly read all HTTP response and only then read first N bytes out of it. So at the end you ended up downloading the whole 1Gb malicious response.
curl <url> | head -c 499
curl <url> | dd count=499
Also there are simpler utils with perhaps borader availability like
netcat host 80 <<"HERE" | dd count=499 of=output.fragment GET /urlpath/query?string=more&bloddy=stuff HERE