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Testing a fix for SSH login detection heuristic.

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This commit is contained in:
Seth Hall 2011-10-25 00:01:04 -04:00
parent 7f838b6181
commit e6a8489780
1 changed files with 8 additions and 4 deletions
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12
scripts/base/protocols/ssh/main.bro
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@ -107,21 +107,25 @@ function check_ssh_connection(c: connection, done: bool)
if ( !c$resp?$num_bytes_ip ) if ( !c$resp?$num_bytes_ip )
return; return;
local server_bytes = c$resp$num_bytes_ip -
c$resp$num_pkts*32 - # Cut the TCP header
c$resp$num_pkts*20; # Cut the IP header (TODO: fix for IPv6)
# If this is still a live connection and the byte count has not # If this is still a live connection and the byte count has not
# crossed the threshold, just return and let the resheduled check happen later. # crossed the threshold, just return and let the resheduled check happen later.
if ( !done && c$resp$num_bytes_ip < authentication_data_size ) if ( !done && server_bytes < authentication_data_size )
return; return;
# Make sure the server has sent back more than 50 bytes to filter out # Make sure the server has sent back more than 50 bytes to filter out
# hosts that are just port scanning. Nothing is ever logged if the server # hosts that are just port scanning. Nothing is ever logged if the server
# doesn't send back at least 50 bytes. # doesn't send back at least 50 bytes.
if ( c$resp$num_bytes_ip < 50 ) if ( server_bytes < 50 )
return; return;
c$ssh$direction = Site::is_local_addr(c$id$orig_h) ? OUTBOUND : INBOUND; c$ssh$direction = Site::is_local_addr(c$id$orig_h) ? OUTBOUND : INBOUND;
c$ssh$resp_size = c$resp$num_bytes_ip; c$ssh$resp_size = server_bytes;
if ( c$resp$num_bytes_ip < authentication_data_size ) if ( server_bytes < authentication_data_size )
{ {
c$ssh$status = "failure"; c$ssh$status = "failure";
event SSH::heuristic_failed_login(c); event SSH::heuristic_failed_login(c);