Dear Hugo van der Kooij, --Friday, July 23, 2004, 10:21:22 PM, you wrote to bugtraq@xxxxxxxxxxxxxxxxx: HvdK> Both as NitroEngine or CVP server they will push as much of 80% to the HvdK> end-user before they stop a virus. Then they rely on the adding of the HvdK> exact URL so that URL can be blocked in all next requests. It depends on how antiviral check is actually implemented. If connection is broken immediately after signature is detected - there is no way to download infected file, because signature will not pass to client and client will not be able to use "Range:" header to resume partially downloaded file. If antiviral filter checks data _after_ all data received from client with 20% buffering yes, it's possible to bypass this check for HTTP, because there is no way (at least for HTTP/1.0 and FTP) to indicate error to client and make him to delete partially downloaded data. You can check it, by sending EICAR with some additional data: if you can find EICAR signature on the client after connection is broken by antiviral filter you can bypass it's protection. -- ~/ZARAZA Машина оказалась способной к единственному действию, а именно умножению 2x2, да и то при этом ошибаясь. (Лем)
