[Snort-users] RE: Simple FTP Login Request rule.........................

JPP jpp at ...1565...
Thu Apr 1 21:13:01 EST 2004


 >Matt Kettler wrote:
 >
 >>At 03:41 PM 4/1/2004, JPP wrote:>
 >>
 >>Anyone have a rule to capture and alert on FTP login requests ONLY?>
 >The rules we currently have capture either all FTP's inbound and 
 >>generate a lot of entries at times, and the standard rules in 
 >ftp.rules >which to this point have generated none.
 >>
 >>A rule I have tried (in several variations) goes something like:
 >>alert tcp any any -> $HOME_NET 21 (msg:"FTP Password/Login attempt" \
 >>   flow:to_server,established; content:"Password"; nocase;)
 >>
 >>I fooled around with the wording,
 >>added content:"USER"; nocase;
 >>and/or
 >>added content:"ogin"; nocase;
 >>and still not a single hit when I log onto a server. I SEE Password: 
 >>when I log in manually so obviously something in my logic or my 
 >>general >understanding of rules is lacking.
 >>>Any wise rule writers out there that can assist would be greatly 
 >>>appreciated!
 >
 >
 >Your head is turned around looking backwards... [:)]
 >
 >All those strings don't go to the server... they come _from_ the 
server >and go to the client.. so of course your rule isn't firing..
 >
 >Re-write your rule's sense of direction using something like this 
 >instead:
 >
 >alert tcp $HOME_NET 21  -> any any  (msg:"FTP Password/Login prompt 
 >outbound" \
 >   flow:from_server,established; content:"Password"; nocase;)
 >

Thanks Matt

Final rule that works for both SSH and FTP (and presumably for POP and 
the like) is:

alert tcp $HOME_NET 20:21 -> any any  (msg:"FTP Password/Login prompt
    outbound" flow:from_server; content:"Password"; nocase;)

(format to fit your screen!)

Thanks again. *adds that to library of never ending knowledge*

JPP





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