- Remove all of the x-c detections. Nearly all false
positives.
- Remove the back up TAR detections. Not very helpful.
- Remove one of the x-elc detections that was too loose
and caused many false positives.
- Change to the default BOF buffer size to 3000 (was 1024).
- Reorganized MS signatures into a separate file
- Improved lots of the signatures and added new ones.
- This moves the signatures out of the libmagic imported signatures
and into our own general.sig.
- Expand the detection to LZMA compressed flash files.
with a MIME type.
Whenever that MIME is detected, Bro will now automatically activate
the analyzer. The interface mimics how well-known ports are defined
for protocol analyzers.
This isn't actually used by any existing file analyzer (because we
don't have any yet that target a specific file format), but there's a
test making sure it works.
* origin/topic/jsiwek/file-signatures:
File type detection changes and fix https.log {orig,resp}_fuids fields.
Various minor changes related to file mime type detection.
Refactor common MIME magic matching code.
Replace libmagic w/ Bro signatures for file MIME type identification.
Conflicts:
scripts/base/init-default.bro
testing/btest/Baseline/coverage.bare-load-baseline/canonified_loaded_scripts.log
testing/btest/Baseline/coverage.default-load-baseline/canonified_loaded_scripts.log
BIT-1143 #merged
- Removed "binary" and "octet-stream" mime type detections. They don't
provide any more information than an uninitialized mime_type field
which implicitly means no magic signature matches and so the media
type is unknown to Bro.
- Slight change to "text/plain" signature. It's still not the most
accurate, which is reflected in its -20 strength value.
- The logic for adding file ids to {orig,resp}_fuids fields of
the http.log incorrectly depended on the state of
{orig,resp}_mime_types fields, so sometimes not all file ids
associated w/ the session were logged.
- Improve or just remove some file magic signatures ported from libmagic
that were too general and matched incorrectly too often.
- Fix MHR script's use of fa_file$mime_type before checking if it's
initialized. It may be uninitialized if no signatures match.
- The "fa_file" record now contains a "mime_types" field that contains
all magic signatures that matched the file content (where the
"mime_type" field is just a shortcut for the strongest match).
Notable changes:
- libmagic is no longer used at all. All MIME type detection is
done through new Bro signatures, and there's no longer a means to get
verbose file type descriptions (e.g. "PNG image data, 1435 x 170").
The majority of the default file magic signatures are derived
from the default magic database of libmagic ~5.17.
- File magic signatures consist of two new constructs in the
signature rule parsing grammar: "file-magic" gives a regular
expression to match against, and "file-mime" gives the MIME type
string of content that matches the magic and an optional strength
value for the match.
- Modified signature/rule syntax for identifiers: they can no longer
start with a '-', which made for ambiguous syntax when doing negative
strength values in "file-mime". Also brought syntax for Bro script
identifiers in line with reality (they can't start with numbers or
include '-' at all).
- A new Built-In Function, "file_magic", can be used to get all
file magic matches and their corresponding strength against a given
chunk of data
- The second parameter of the "identify_data" Built-In Function
can no longer be used to get verbose file type descriptions, though it
can still be used to get the strongest matching file magic signature.
- The "file_transferred" event's "descr" parameter no longer
contains verbose file type descriptions.
- The BROMAGIC environment variable no longer changes any behavior
in Bro as magic databases are no longer used/installed.
- Reverted back to minimum requirement of CMake 2.6.3 from 2.8.0
(it's back to being the same requirement as the Bro v2.2 release).
The bump was to accomodate building libmagic as an external project,
which is no longer needed.
Addresses BIT-1143.
- The reassembly behavior can be modified per-file by enabling or
disabling the reassembler and/or modifying the size of the reassembly
buffer.
- Changed the file extraction analyzer to use the stream to avoid
issues with the chunk based approach not immediately triggering
the file_new event due to mime-type detection delay. Early chunks
frequently ended up lost before.
- Generally things are working now and I'd consider this in testing.
- Enable manager to associate analyzers with a MIME type. With that,
one can now say enable all analyzers for, e.g., "image/gif". This is
exposed to script-land as
Files::add_analyzers_for_mime_type(f: fa_file, mtype: string)
For MIME types identified via libmagic, this happens automatically
(via the file_new() handler in files/main.bro).
- Extend the analyzer API to better match that of protocol analyzers:
- Adding unique analyzer IDs so that we can refer to instances
from script-land.
- Adding subtypes to Components so that a single analyzer
implementation can support different types of analyzers
internally.
- Add an analyzer method SetTag() that allows to set the tag after
construction.
- Adding Init() and Done() methods for consistency with what other
classes offer.
- Add debug logging to the file_analysis stream.
TODO: test cases missing for the new script-land functionality.
Fixed reference to wrong field name.
Added documentation of a function arg.
Added a couple references to other parts of the documentation.
Explained how not specifying extraction filename results in automatic
filename generation.
Several other minor clarifications.
The text from these README files appears on the "Bro Script Packages"
page after building the documentation. The text for these was mostly just
copied from the existing docs.
This cleans up internals of how analyzer instances get identified by the
tag plus any args given to it and doesn't change script code a user
would write.
- Fix examples/references in the file analysis how-to/usage doc.
- Add Broxygen-generated docs for file analyzer plugins.
- Break FTP::Info type declaration out in to its own file to get
rid of some circular dependencies (between s/b/p/ftp/main and
s/b/p/ftp/utils).
- Several places were just using old variable names or not loading
scripts correctly after they'd been renamed/moved.
- Revert/adjust a change in how HTTP file handles are generated that
broke partial content responses.
- Turn some libmagic builtin checks back on; seems some are actually
useful (e.g. text detection seems to be a builtin). The rule going
forward probably will be only to turn off a builtin if we confirm it
causes issues.
- Removed some tests that are redundant or not necessary anymore because
the generic file analysis tests cover them.
- A couple FTP tests still fail that I think need an actual solution via
script changes.
- Recorrected the module name to Files.
- Added Files::analyzer_name to get a more readable name for a
file analyzer.
- Improved and just overall better handled multipart mime
transfers in HTTP and SMTP. HTTP now has orig_fuids and resp_fuids
log fields since multiple "files" can be transferred with
multipart mime in a single request/response pair. SMTP has
an fuids field which has file unique IDs for all parts
transferred. FTP and IRC have a log field named fuid added
because only a single file can be transferred per irc and ftp
log line.
