[Snort-sigs] false positives for attack-response rules (and suggested fix)
Paolo.Milani at ...1843...
Fri Mar 19 04:57:02 EST 2004
concerning sids 1292:
alert tcp $HOME_NET any -> $EXTERNAL_NET any (msg:"ATTACK-RESPONSES directory listing"; content: "Volume Serial Number"; flow:from_server,established; classtype:bad-unknown; sid:1292; rev:7;)
alert ip $HOME_NET any -> $EXTERNAL_NET any (msg:"ATTACK-RESPONSES id check returned userid"; content:"uid="; byte_test:5,<,65537,0,relative,string; content:" gid="; distance:0; within:15; byte_test:5,<,65537,0,relative,string; classtype:bad-unknown; sid:1882; rev:9;)
In some environments it can be normal to have telnet traffic in the network (not in very safe environments, I know). In which case these rules will fp a lot.
My suggestion is to change src port to !23 (or !$TELNET_PORTS).
This will not make environments where telnet traffic is not allowed less safe, I think, since telnet traffic is already detected with specific signatures.
my 2 cents,
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