Snort mailing list archives
Re: pass rules for one alert
From: John Sage <jsage () finchhaven com>
Date: Tue, 3 Sep 2002 07:46:21 -0700
Addy: On Tue, Sep 03, 2002 at 03:15:45AM -0400, Night-Stalker wrote:
Hello John, the Payload, that snort logs looks like this: length = 131 LIST..PASV..CDW //directory1/directory2..LIST..PASV.. CWD //directory3/directory4..LIST..PASV.. As I can see, it must be hourly cron-job from host1 to host2 via
FTP. Every hour, I get 5 false positives of this alert. Only between these hosts. My pass-rule, I wrote below doesn't work, or it works but also triggers the alert-rule. As I wrote, I only want to ignore this false positive between these hosts and I dont't want to comment out the complete alert-rule to ignore all these alerts. I also don't want to write a pass-rule to ignore the complete FTP-Transfers between these hosts.
Can anybody help me out?
If that's the *specific* string you're *always* seeing, I'd think adding something like: pass tcp <source-ip> any -> <dest-ip> 21 (msg:"FTP command overflow \ attempt"; uricontent:"LIST..PASV..CDW"; nocase; flags:A+; dsize:>100; \ reference:bugtraq,4638; classtype:protocol-command-decode; sid:1748; \ rev:3;) should do the trick.. Contrariwise, if it's *always* from "host1" then: pass tcp <HOST1-source-ip> any -> <dest-ip> 21 (msg:"FTP command overflow attempt"; flags:A+; dsize:>100; reference:bugtraq,4638; classtype:protocol-command-decode; sid:1748; rev:3;) but the problem there is that it's host-specific... - John
John Sage <jsage () finchhaven com> wrote:Addy: **-- snip --** pass tcp <source-ip> any -> <dest-ip> 21 (msg:"FTP command overflow attempt"; flags:A+; dsize:>100; reference:bugtraq,4638; classtype:protocol-command-decode; sid:1748; rev:3;)This is looking at a packet payload size > 100; this is not specific enough? What *would* make it specific enough? See below...I don't want to ignore all FTP-Data between these hosts, only the FTP-Data that triggers this alert (thats means the pass-rule: pass tcp <source-ip> any -> <dest-ip> 21 isn't precise enough. And ignores all FTP-Data.) Is it possible to ignore exactly the FTP-Data between these Hosts, that triggers that alert. I want the other FTP-Data between these Hosts being scanned for other FTP-Exploits except the "FTP command overflow attempt".In a word, yes, but if you want help from anyone on this list you'll have to tell *us* what "..exactly the FTP-Data between these Hosts.." is, because until we know, no one can help you... - John -- "In those days, you could not buy a $2000 200MHz Pentium server."
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Current thread:
- pass rules for one alert Night-Stalker (Sep 02)
- Re: pass rules for one alert Matt Kettler (Sep 02)
- Re: pass rules for one alert John Sage (Sep 02)
- <Possible follow-ups>
- Re: pass rules for one alert Night-Stalker (Sep 03)
- Re: pass rules for one alert John Sage (Sep 03)
- Re: pass rules for one alert Chris Green (Sep 03)