This commit fixes three issues with Zeek's Modbus message logging:
1 - Some exception responses (e.g., READ_COILS_EXCEPTION) are logged
twice: once without and once with the exception message.
2 - Some exception responses (e.g., PROGRAM_484_EXCEPTION) are not
logged.
3 - Some known but reserved function codes (e.g., PROGRAM_UNITY) are
logged as unk-xxx (e.g., unk-90), while it would be possible to
log their known name.
To address these inconsistencies, the modbus parser has been updated
to parse all exception responses (i.e., all responses where the MSB
of the function code is set) using the already defined Exception
message.
Also, the Modbus main.zeek script has been updated to consistently
demand logging exception responses to the specialized
modbus_exception event, rather than logging some exception responses
in the modbus_message event and others in the modbus_exception event.
Finally, the main.zeek script has been updated to make sure that
for every known function code, the corresponding exception code was
also present, and the enumeration of known function codes in
consts.zeek has been expanded.
Closes#3984
This changes many weird names to move non-static content from the
weird name into the "addl" field to help ensure the total number of
weird names is reasonably bounded. Note the net_weird and flow_weird
events do not have an "addl" parameter, so information may no longer
be available in those cases -- to make it available again we'd need
to either (1) define new events that contain such a parameter, or
(2) change net_weird/flow_weird event signature (which is a breaking
change for user-code at the moment).
Also, the generic handling of binpac exceptions for analyzers which
to not otherwise catch and handle them has been changed from a Weird
to a ProtocolViolation.
Finally, a new "file_weird" event has been added for reporting
weirdness found during file analysis.
This makes conn.logs a bit prettier (and smaller) because all lines that
do not use a tunnel will now have a "-" instead of the "(empty)" for
tunnel_parents.
- Add a timeout flag to file_analysis.log so it's easy to tell what
has had at least one timeout trigger happen.
- Fix ftp-data service tag not being set for reused connections.
- Fix HTTP::Incorrect_File_Type because mime types returned by FAF have
the charset still in them, but the HTTP::mime_types_extensions table
does not and it requires an exact string match. (still ugly)
- Add TRIGGER_NEW_CONN to track files going over multiple connections.
- Add an initial file/mime type guess for non-linear file transfers.
- Fix a case where file/mime type detection would never be attempted
if the start of the file was a content gap.
- Improve mime type tracking of HTTP byte-range/partial-content,
even if the requests are pipelined or over multiple connections.
- I changed the modbus.events test because having the baseline output
be 80+ MB is nuts and it was sensitive to connection record redefs.
- Added a test for binpac exception handling -- the generated code
should use "binpac::Exception" and not "Exception" for exception
handling logic to avoid accidental overshadowing by
the analyzer-specific type "binpac::ModbusTCP::Exception", which
could lead to interesting asserts being triggered in binpac.
- Update baseline for the event coverage test -- seems that more
events get generated with working exception handling in the generated
binpac parser code.
- Coverage baseline was giving wrong number of events covered.
* origin/topic/dina/modbus:
put some make-up on Modbus analyser
Modbus analyser, added support: FC=20,21
Modbus analyzer,added support: FC=1,2,15,24
Modbus analyzer, current support: FC=3,4,5,6,7,16,22,23
I cleaned up the code a bit, mainly layout style.
I did not include the *.bro scripts for now, but a test script
../testing/btest/scripts/base/protocols/modbus/events.bro that prints
out the value for each event.
Merged the Modbus traces from the ics repository into a single trace
as input for the test. They currently trigger 20 of the 34 events.
Addresses #870.
