[Oisf-users] PCRE question

Victor Julien victor at inliniac.net
Wed Jul 11 17:34:34 EDT 2012


8.31 is also out already :)

On 07/11/2012 11:22 PM, Will Metcalf wrote:
> Ancient pcre version?
> /pcretest -C
> PCRE version 8.30 2012-02-04
> Compiled with
>   8-bit support only
>   UTF-8 support
>   Unicode properties support
>   Just-in-time compiler support: x86 64bit (little endian + unaligned)
>   Newline sequence is LF
>   \R matches all Unicode newlines
>   Internal link size = 2
>   POSIX malloc threshold = 10
>   Default match limit = 10000000
>   Default recursion depth limit = 10000000
>   Match recursion uses stack
> 
> 
> On Wed, Jul 11, 2012 at 1:49 PM, Brandon Ganem
> <brandonganem+oisf at gmail.com <mailto:brandonganem+oisf at gmail.com>> wrote:
> 
>     Kay,
>     I've got a bunch of signatures doing this. For example:
>     [18575] 11/7/2012 -- 13:22:40 - (detect-pcre.c:949) <Error>
>     (DetectPcreParse) -- [ERRCODE: SC_ERR_PCRE_STUDY(6)] - pcre study
>     failed : unknown or incorrect option bit(s) set
>     [18575] 11/7/2012 -- 13:22:40 - (detect.c:547) <Error>
>     (DetectLoadSigFile) -- [ERRCODE: SC_ERR_INVALID_SIGNATURE(39)] -
>     error parsing signature "alert http $EXTERNAL_NET any -> $HOME_NET
>     any (msg:"ET WEB_CLIENT Microsoft Internet Explorer SameID
>     Use-After-Free "; flow:established,from_server; content:"<DIV id=";
>     nocase; content:"<img id="; nocase; distance:0;
>     content:".innerHTML"; distance:0;
>     pcre:"/<DIV\s*?id[\s\r\n]*?\x3d[\s\r\n]*?(?P<divid>[^>]+).+?<img\s*id=\s*?\x22(?P<imgid>[^\x22]+).+?\<a\s*?href=\x22javascript\x3a(?P<firstfunction>[^\x28]+)\(\).+?\>.*?\<div[^\>]+?id=\x22(?P=imgid)\x22[^>]+?on[A-Za-z]+?\s*?=\s*?\x22(?P<secondfunction>[^\x28]+)\(\)\x3b\s*?\x22.+?function[\s\r\n]*?(?P=firstfunction)[\s\r\n]*?\(.*?\).*?\x7b.*?(?P=divid)\x2einnerHTML\s*?\x3d\s*?(?P=divid)\x2einnerHTML[\s\r\n]*?\x3b.*?\x7d.*?function[\s\r\n]*?(?P=secondfunction)[\s\r\n]*?\(.*?\).*?\x7b.*?\x28\x22(?P=imgid)\x22\x29\x2esrc\s*?\x3d/si";
>     reference:cve,CVE-2012-1875; classtype:attempted-user; sid:2014911;
>     rev:10;)" from file /etc/suricata/rules/etpro/web_client.rules at
>     line 1916
>     http://doc.emergingthreats.net/bin/view/Main/2014911
> 
>     It doesn't seem to be related to the pcre options. I created a sig
>     without any options:
>     alert tcp any any -> any any (msg:"test .jar sig"; content:".jar";
>     nocase; http_uri; pcre: "/\d{5}\.jar/"; classtype:trojan-activity;
>     sid:2055555555555500349; rev:1;)
> 
>     regardless of the pcre options it blows up. However if I get ride of
>     the pcre statement it works fine.
> 
>     Thanks!
> 
>     On Wed, Jul 11, 2012 at 2:33 PM, kay <kay.diam at gmail.com
>     <mailto:kay.diam at gmail.com>> wrote:
> 
>         Thanks for info, now I know more about it. But it is a custom
>         suricata
>         modifier. I would suggest the author to try start suricata without
>         this modifier.
> 
>         2012/7/11 Chris Wakelin <c.d.wakelin at reading.ac.uk
>         <mailto:c.d.wakelin at reading.ac.uk>>:
>         > On 11/07/2012 19:06, kay wrote:
>         >> I have noticed /H modifier. I've never heard about such modifier.
>         >>
>         >> "/Host\x3a ([0-9]{1,3}\.){3}[0-9]{1,3}/H"
>         >
>         > From
>         >
>         https://redmine.openinfosecfoundation.org/projects/suricata/wiki/HTTP-keywords
>         > :-
>         >> H       Makes pcre match on the HTTP-header.  H can be
>         combined with /R. Note that R is relative to the
>         >>         previous match so both matches have to be in the
>         HTTP-header body.
>         >
>         > plus several others!
>         >
>         > Best Wishes,
>         > Chris
>         >
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> 
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Victor Julien
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