[Snort-sigs] New sig for detecting audit SVG Files contains JavaScript (possible Malicious)

Joshua Williams joshuwi2 at ...435...
Wed Jan 25 16:19:34 EST 2017


rmkml,

Thanks for your submission. I'll review and test these and get back to you
when they're finished.

--
Josh Williams
Detection Response Team
TALOS Security Group

On Wed, Jan 25, 2017 at 3:28 PM, rmkml <rmkml at ...4129...> wrote:

> Hi,
>
> First, Thx ISC Sans for sharing recent Malicious SVG Files,
>
> Please check two new sigs for detecting audit SVG Files contains
> JavaScript (possible Malicious):
>
> First sig detect SVG files:
> -it's a first public version, another check is possible like
> Content-Type...
> -check if you don't have existing SVG flowbits on your ruleset...
> -enhance with regex for reduce possible FP...
>
> alert tcp $EXTERNAL_NET any -> $HOME_NET $HTTP_PORTS (msg:"WEB-MISC Svg
> flowbits noalert"; flow:to_server,established; content:".svg"; nocase;
> http_uri; flowbits:set,http.svgfound; flowbits:noalert;
> classtype:web-application-activity; sid:1; rev:1; )
>
> Second sig detect audit :
>
> alert tcp $EXTERNAL_NET $HTTP_PORTS -> $HOME_NET any (msg:"WEB-CLIENT Svg
> contains possible JavaScript attempt"; flow:to_client,established;
> flowbits:isset,http.svgfound; file_data; content:"svg"; nocase;
> distance:0; content:"script"; nocase; distance:0;
> pcre:"/(?:\<|\%3c)svg\b.*?(?:\<|\%3c)script\b/si";
> reference:url,isc.sans.edu/forums/diary/Malicious+SVG+
> Files+in+the+Wild/21971/;
> classtype:attempted-user; sid:2; rev:1; )
>
> Don't forget check variables.
>
> Please send any comments.
>
> Regards
> @Rmkml
>
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