Are empty HTTP requests malicious?

Question

I have seen multiple empty http request log entries from Apache:

HOST:443 REMOTEIP - - [DATA AND TIME] "-" SIZE SIZE "-" "-"

Are these malicious attacks, or some misconfiguration on my side?

That first `SIZE` is actually the return code, isn't it one of 400 or 404? — ott--, May 06 '13 at 14:08
The IP is not corresponding to the loopback or the IP of the server ? — Dom, May 06 '13 at 14:50

score 1 · Answer 1 · answered May 06 '13 at 15:56

Empty responses are perfectly normal if e.g. the HTTP return code is 304 (Not modified). The client sending the request is sending headers like If-Modified-Since or If-None-Matches and the server uses them to determine that nothing changed and sends an empty response, allowing the client to use its cached copy.

Are empty HTTP requests malicious?

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