[Oisf-users] DNP3 Preprocessor Keyword Changes

Fred Austin fred.austin at n-dimension.com
Thu Aug 10 14:26:39 UTC 2017

I updated a copy of the Quickdraw Dnp3 rules based on the following:

1) Replace dnp3_cmd_fc with dnp3_func
2) Replace dnp3_cmd_ot with dnp3_obj, a variation value is needed and
research indicated a value of 1 would be appropriate for an object value of
50, but I am not 100% certain
3) Comment out rules that use dnp3_checksum

Most of the rules trigger using the pcap files that come with the Quickdraw
set, including the one using the keyword dnp3_obj.

On Thu, Aug 10, 2017 at 9:18 AM, Jason Ish <ish at unx.ca> wrote:

> Hi Fred,
> > On Aug 9, 2017, at 11:01 AM, Fred Austin <fred.austin at n-dimension.com>
> wrote:
> >
> > Examining the lastest version (v1.3, 2015 on Github) of the Quickdraw
> IDS rules set for Snort/Suricata the DNP3 rules, they contain dnp3 keywords
> which are no longer supported, namely:
> >
> >     - dnp3_cmd_fc
> >     - dnp3_cmd_ot
> >     - dnp3_checksum
> >
> > The currently supported dnp3 keywords are:
> >
> >     - dnp3_func
> >     - dnp3_ind
> >     - dnp3_obj
> >     - dnp3_data
> >
> > I could not find any documentation about the previous dnp3 keywords
> (dnp3_cmd_fc, etc). Does anyone have any documentation about the previous
> dnp3 keywords and how they map to the new (supported) keywords? At first
> guess, I would assume that "dnp3_cmd_fc" maps to "dnp3_func", but it is not
> clear about the other keywords.
> To the best of my knowledge Suricata has never been compatible with the
> Quickdraw DNP3 rules, instead our DNP3 keywords are designed to be
> compatible with those built into Snort. Unfortunately while those keywords
> above are used in some rulesets, they have never worked with Suricata.  At
> some point I’d like to look at the Quickdraw rules and rewrite them for
> Suricata, but I’m not sure when I can get around to that.
> Jason

Fred Austin
VP Product Development
N-Dimension Solutions

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