Mirror/zeek
1
0
Fork 0
mirror of https://github.com/zeek/zeek.git synced 2025-10-02 06:38:20 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions 1

Merge remote-tracking branch 'origin/topic/johanna/conn-threshold'

Browse source 
* origin/topic/johanna/conn-threshold:
  Wrap threshold stuff up - fix two small bugs and update baselines.
  update GridFTP analyzer to use connection thresholding instead of polling
  Add high level api for thresholding that holds lists of thresholds and raises an event for each threshold exactly once.
  Allow setting packet and byte thresholds for connections.

BIT-1377 #merged
This commit is contained in:
Robin Sommer 2015-04-17 13:02:31 -07:00
commit 1e010fbb76
23 changed files with 877 additions and 218 deletions
Download patch file Download diff file Expand all files Collapse all files

65
scripts/base/protocols/ftp/gridftp.bro
View file

@ -11,13 +11,13 @@
##! GridFTP data channels are identified by a heuristic that relies on
##! the fact that default settings for GridFTP clients typically
##! mutually authenticate the data channel with TLS/SSL and negotiate a
##! NULL bulk cipher (no encryption). Connections with those
##! attributes are then polled for two minutes with decreasing frequency
##! to check if the transfer sizes are large enough to indicate a
##! GridFTP data channel that would be undesirable to analyze further
##! (e.g. stop TCP reassembly). A side effect is that true connection
##! sizes are not logged, but at the benefit of saving CPU cycles that
##! would otherwise go to analyzing the large (and likely benign) connections.
##! NULL bulk cipher (no encryption). Connections with those attributes
##! are marked as GridFTP if the data transfer within the first two minutes
##! is big enough to indicate a GripFTP data channel that would be
##! undesirable to analyze further (e.g. stop TCP reassembly). A side
##! effect is that true connection sizes are not logged, but at the benefit
##! of saving CPU cycles that would otherwise go to analyzing the large
##! (and likely benign) connections.
@load ./info
@load ./main
@ -32,23 +32,14 @@ export {
## GridFTP data channel.
const size_threshold = 1073741824 &redef;
## Max number of times to check whether a connection's size exceeds the
## Time during which we check whether a connection's size exceeds the
## :bro:see:`GridFTP::size_threshold`.
const max_poll_count = 15 &redef;
const max_time = 2 min &redef;
## Whether to skip further processing of the GridFTP data channel once
## detected, which may help performance.
const skip_data = T &redef;
## Base amount of time between checking whether a GridFTP data connection
## has transferred more than :bro:see:`GridFTP::size_threshold` bytes.
const poll_interval = 1sec &redef;
## The amount of time the base :bro:see:`GridFTP::poll_interval` is
## increased by each poll interval. Can be used to make more frequent
## checks at the start of a connection and gradually slow down.
const poll_interval_increase = 1sec &redef;
## Raised when a GridFTP data channel is detected.
##
## c: The connection pertaining to the GridFTP data channel.
@ -79,23 +70,27 @@ event ftp_request(c: connection, command: string, arg: string) &priority=4
c$ftp$last_auth_requested = arg;
}
function size_callback(c: connection, cnt: count): interval
event ConnThreshold::bytes_threshold_crossed(c: connection, threshold: count, is_orig: bool)
{
if ( c$orig$size > size_threshold || c$resp$size > size_threshold )
if ( threshold < size_threshold || "gridftp-data" in c$service || c$duration > max_time )
return;
add c$service["gridftp-data"];
event GridFTP::data_channel_detected(c);
if ( skip_data )
skip_further_processing(c$id);
}
event gridftp_possibility_timeout(c: connection)
{
# only remove if we did not already detect it and the connection
# is not yet at its end.
if ( "gridftp-data" !in c$service && ! c$conn?$service )
{
add c$service["gridftp-data"];
event GridFTP::data_channel_detected(c);
if ( skip_data )
skip_further_processing(c$id);
return -1sec;
ConnThreshold::delete_bytes_threshold(c, size_threshold, T);
ConnThreshold::delete_bytes_threshold(c, size_threshold, F);
}
if ( cnt >= max_poll_count )
return -1sec;
return poll_interval + poll_interval_increase * cnt;
}
event ssl_established(c: connection) &priority=5
@ -118,5 +113,9 @@ event ssl_established(c: connection) &priority=-3
# By default GridFTP data channels do mutual authentication and
# negotiate a cipher suite with a NULL bulk cipher.
if ( data_channel_initial_criteria(c) )
ConnPolling::watch(c, size_callback, 0, 0secs);
{
ConnThreshold::set_bytes_threshold(c, size_threshold, T);
ConnThreshold::set_bytes_threshold(c, size_threshold, F);
schedule max_time { gridftp_possibility_timeout(c) };
}
}