A detection script for GridFTP data and control channels.
GridFTP control channels are identified by FTP control channels
that successfully negotiate the GSSAPI method of an AUTH request
and for which the exchange involved an encoded TLS/SSL handshake,
indicating the GSI mechanism for GSSAPI was used. This analysis
is all supported internally, this script simply adds the “gridftp”
label to the service field of the control channel’s
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 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.
|Imports:||base/frameworks/notice, base/protocols/conn, base/protocols/ftp/info.bro, base/protocols/ftp/main.bro, base/protocols/ssl|
||Time during which we check whether a connection’s size exceeds the
||Number of bytes transferred before guessing a connection is a GridFTP data channel.|
||Whether to skip further processing of the GridFTP data channel once detected, which may help performance.|
Time during which we check whether a connection’s size exceeds the
Number of bytes transferred before guessing a connection is a GridFTP data channel.
The initial criteria used to determine whether to start polling the connection for the
GridFTP::size_thresholdto have been exceeded. This is called in a
ssl_establishedevent handler and by default looks for both a client and server certificate and for a NULL bulk cipher. One way in which this function could be redefined is to make it also consider client/server certificate issuer subjects.
C: The connection which may possibly be a GridFTP data channel. Returns: true if the connection should be further polled for an exceeded
GridFTP::size_threshold, else false.