Broken thresholding in 2923.1 and 2924.1?

Rule: NETBIOS SMB repeated logon failure
Rule: NETBIOS SMB-DS repeated logon failure

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Sid: 2923, 2924

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Rules 2923.1 and 2924.1 are monitoring failed login server responses 
so it seems to me that they should be thresholding on destination, not 
source:

alert tcp $HOME_NET 139 -> $EXTERNAL_NET any 
(msg:"NETBIOS SMB repeated logon failure"; 
flow:from_server,established; 
content:"|ff|SMB"; offset:4; depth:4; 
content:"|73|"; distance:0; within:1; 
content:"|6d0000c0|"; distance:0; within:4; 
threshold:type threshold,track by_dst,count 10,seconds 60; 
classtype:unsuccessful-user; sid:2923; rev:2;) 

alert tcp $HOME_NET 445 -> $EXTERNAL_NET any 
(msg:"NETBIOS SMB-DS repeated logon failure"; 
flow:from_server,established; 
content:"|ff|SMB"; offset:4; depth:4; 
content:"|73|"; distance:0; within:1; 
content:"|6d0000c0|"; distance:0; within:4; 
threshold:type threshold,track by_dst,count 10,seconds 60; 
classtype:unsuccessful-user; sid:2924; rev:2;) 


Or is the intent of these two rules to track distributed cracking?


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