[Snort-users] Trouble with home-made rule

Dragos Ruiu dr at ...381...
Sun Jun 17 19:30:35 EDT 2001


This is a kind of esoteric problem that is likely to bite
people who are new to C or unfamiliar with C strings.  
We ought to put a quick little check for backslashes 
and a warning message in the parser to make this 
easier to figure out in the future... I'll send you a 
patch Marty...  I've also been meaning to make 
the port #'s optional for ICMP rules too rather than 
having to put in bogus values...

cheers,
--dr

On Sunday 17 June 2001 23:14, Dragos Ruiu wrote:
> Your problem is with the backslash before the quote....
> \" is how you escape a quote inside the content string
> so it looks like an unterminated string to the parser.
>
> try:
>
> "C:\\"
>
> and remember to add another rule for lowercase:
>
> "c:\\"
>
> the slash in the message string may be a problem too.
> I'd double it up just to make sure....
>
> cheers,
> --dr
>
> On Monday 18 June 2001 05:51, Sheahan, Paul (PCLN-NW) wrote:
> > Hello,
> >
> > I'm expermenting for the first time creating my own rules. I decided to
> > create a rule that detects whenever one of my servers responds to an
> > external address with "C:\" in the packet in case my servers are giving
> > out any info on the local drive without my knowledge. I added this rule:
> >
> > alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"Outgoing c:\";
> > content: "c:\"; nocase;)
> >
> > And received this error when starting Snort (the rule above is on line
> > 16):
> >
> > ERROR Line 16 => Content data needs to be enclosed in quotation marks
> > (")!
> >
> > Obviously the closed quotation is there. I thought maybe the ":" in "C:\"
> > is confusing Snort? Just a guess. Anyone know how I can fix this?
> >
> > Thanks!
> >
> >
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