Bugtraq: Re: eSafe: Could this be exploited?

[MegaHz <megahz () gmail com>]

I have tested it out, and esafe blocked the hole email that contains
the eicar virus.
Of course I have configure esafe to block virus infected emails
instead of modifying them and removing the virus.

MegaHz
www.megahz.org
megahz () megahz org


On Sat, 24 Jul 2004 15:27:43 +0400, 3APA3A <3apa3a () security nnov ru> wrote:
> Dear Hugo van der Kooij,
>
> --Friday, July 23, 2004, 10:21:22 PM, you wrote to bugtraq () securityfocus com:
>
> 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)