[Snort-users] How to detect drive letters accessed?

John Sage jsage at ...2022...
Thu Jan 17 20:29:04 EST 2002

I kinda lurked on this thread until tonight I remembered an entirely 
different tool you might use to set up a rule that covers a range of 
drive letters (or any other complex syntax...)

The tool is ngrep (network grep), see:




ngrep allows you to make complex regex expressions and use them to watch 
packet contents, kinda like snort and/or tcpdump but on steroids..

To quote from the incidents.org article:

"...The problem comes when we don't have a fixed series of  characters 
to match against.

The November 2001  wu-ftpd exploit used the fact that a sequence of 
whitespace, a
tilde, optional characters, a left curly brace, and any other characters 
  without a matching right curly brace would crash wu-ftpd, allowing a 
buffer overflow exploit to take over.

Because of the possibility of additional characters and the  requirement 
that the second block of characters not contain a "}", we   need to use 
something stronger than fixed strings..."

- John

The web page you seek
cannot be found here:
countless others await

> -----Original Message-----
> From: snort-users-admin at lists.sourceforge.net
> [mailto:snort-users-admin at lists.sourceforge.net]On Behalf Of Sheahan,
> Paul (PCLN-NW)
> Sent: Wednesday, January 16, 2002 5:20 PM
> To: Snort List (E-mail)
> Subject: [Snort-users] How to detect drive letters accessed?
> Running Snort 1.8.1 B78 on RH Linux 7.0.
> Using Snort, I am trying to detect when someone accesses a certain drive on
> one of my servers. For example if I have a server that has a drive letter K:
> that no one from the outside world should see or be accessing, I'd like to
> create a rule in Snort that checks for "K:\" in a packet. The trouble is, I
> can't just create a rule that searches for "K:\" because the rule doesn't
> work. I think the colon screws it up or something. Someone in this forum
> once mentioned putting some type of code in for the colon and backslash
> instead such as creating a rule to look for "K|C3A|" or something like that,
> but all recommendations from that person failed.
> Does anyone know how I can create a rule to search for "K:\" (can be any
> drive letter....it's the colon and backslash that are important)?
> Thanks!
> Paul

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