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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA256 Finally, 14.12.15 2:22, Markus пишет: > hi, > thanks for your help guys. I suspected that ICAP will be necessary. > but I thought that even ICAP checks it only by the file extension or > by server response (mime-type). Surprisingly Diladele is able to check Think more. ALL ICAP solutions checks content. Diladele is not only solution which checks content. > the first bytes of file content, which is exactly what I wanted. > On the other hand I don't want to check exe files by external AV for 2 reasons > 1. I don't believe in its effectiveness :) > 2. each user has an comercial AV on his PC You need to learn - not all commercial anti-virus software detects all. And vice versa. Therefore, even if an external antivirus control reduces the probability of malware penetration just twice - it should be used. Also, remember one thing. Caching Proxy can be infected - and then you get a large-scale epidemic, regardless used on the client computer antivirus software or not. I have encountered similar situations in the past and they usually lead to large-scale network failures. > As I said in the first post - I already block exe files by squid ACL. You really think executable files can have only known extension? > Now I'm afraid that some malware software can get through web/http by > omitting this ACL (will be downloaded as jpg). Sure. That is why you will be forced to use only one really existing solution. > > thanks. Now I have to read more about available ICAP servers :) > > On Sun, Dec 13, 2015 at 7:32 PM, Yuri Voinov <yvoinov@xxxxxxxxx> wrote: >> > For malware checking we have two working (and performance) solutions: > > http://wiki.squid-cache.org/ConfigExamples/ContentAdaptation/C-ICAP > http://wiki.squid-cache.org/ConfigExamples/ContentAdaptation/eCAP > > No need to block any and all executables in the world. Just enough to > check it with AV-engine. ;) > > 13.12.15 18:31, Markus пишет: > >>> I'm wondering if it is possible to detect (and block) certain files by > >>> its header/content like 'MZ' (0d 0a 0d 0a 4d 5a) which is a beginning > >>> of any EXE/DLL file. > >>> > >>> Purpose: > >>> > >>> I'm trying to protect my internal network against unconsciously > >>> downloading executable files (like malware). All users traffic pass > >>> through our Squid proxy. > >>> > >>> What I've already done is: > >>> > >>> 1. Blocking by URL (url contains \.exe \.dll and other banned extensions) > >>> 2. Blocking by server's response header (MIME-type , > >>> Content-Disposition and so on.) > >>> > >>> But there is still a way to download an executable file when somebody > >>> put it on server as e.g. readme.txt. Server's response header would be > >>> in this case 'Content-Type: text/html;'. > >>> > >>> So none of above mentioned rules would block this file. Of course, a > >>> regular Web browser would show this EXE as text, which isn't > >>> dangerous. But we can imagine a dedicated downloader (e.g. a part of > >>> the malware) which can download binary code this way. > >>> > >>> So, tell me guys, if there is any solution for this? > >>> > >>> I could also use "Snort", but it would be very inflexible (I would > >>> like to have a whitelist of domains). > >>> > >>> even if it's possible, what about performance in real environment? > >>> maybe there's a way to analyze only the first bytes of the incoming > >>> stream? > >>> > >>> greetings > >>> Markus > >>> > >>> PS > >>> ---- > >>> if the string 'MZ' is too short, we can also use 'This program cannot > >>> be run in DOS mode' (this string is also part of EXE header). But > >>> probably a majority of exe packers can compress it. > >>> _______________________________________________ > >>> squid-users mailing list > >>> squid-users@xxxxxxxxxxxxxxxxxxxxx > >>> http://lists.squid-cache.org/listinfo/squid-users > >> >> _______________________________________________ >> squid-users mailing list >> squid-users@xxxxxxxxxxxxxxxxxxxxx >> http://lists.squid-cache.org/listinfo/squid-users > _______________________________________________ > squid-users mailing list > squid-users@xxxxxxxxxxxxxxxxxxxxx > http://lists.squid-cache.org/listinfo/squid-users -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAEBCAAGBQJWbdlQAAoJENNXIZxhPexGJTUH/2DC/xG9EsI5oR0VHJsKuoid 2gYed3/wEq1uA2VJCZVe2Cbnr9mEkA25Kg6xEUoMUVNGI8zRGimt1BSiXk5HK+7G P0B588oY3R5TpgwwREmF6ZKnqgX6X0weORM2QzEwS0K/FiWOY05LJ4XoX32lqIfq fYokJ2MCtgvRFtXA7vKxokHA5IyG5xgKf4fYfDnXY2wN+yCaYj2GqACpzfNzn9xn Zbiqf1DH0S5hIEac5n1Z5oPmEjcEUgVlkeJ8i8nCCIdsinBAhYVC9TCK9ZDJymuF 1IkBHHJAyj5UoJHOB2k1Nkihx4faRfdLc2rTcNkzXvT34kXjUbXFfvEkz0UYUkU= =fk/o -----END PGP SIGNATURE----- |
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