I agree with Mark. It promotes consistency in the JSON serialization and makes it a lot easier for people to remember.
Paul Patrick
iSIGHT Partners
Personally I like the idea that certain keywords are reserved. Forcing implementers to remember which “type” fields indicate the object type and which “type” fields indicate some other type (e.g., PE binary type, as in the referenced example) would expand
the cognitive load required to “grok” CybOX 3.0 significantly.
Thank you.
-Mark
“Extension_type” is just the required property on all extensions that defines the name of the object extension (which unfortunately collides with the concept of file extensions); I agree with Jason that “metadata_type” is rather abstract and so it may
not be better. I’m fine with just “type” if we feel that it would be a better, standardized approach (it’s actually what we originally had) - the only issue there is that there are other places where “type” is used (e.g., [1]), so they would have to be changed
since “type” would effectively become a reserved keyword.
I also concur with Mark’s points on MIMEType and Magic Number.
Regards,
Ivan
I agree w/ all of Mark’s comments.
Regarding #1, would this be a good place to use the “type” field that EclecticIQ has added to their JSON? It seems to serve the same purpose and if we standardize on that name across STIX, CybOX, and TAXII we’ll make things much easier for users.
John
From: < cti-cybox@lists.oasis-open.org> on behalf of Mark Davidson < mdavidson@soltra.com>
Date: Tuesday, December 22, 2015 at 7:13 AM
To: Ivan Kirillov < ikirillov@mitre.org>, Jason Keirstead < Jason.Keirstead@ca.ibm.com>
Cc: "Wunder, John A." < jwunder@mitre.org>, Jerome Athias < athiasjerome@gmail.com>, Patrick Maroney < Pmaroney@specere.org>,
Sean Barnum < sbarnum@mitre.org>, John Anderson < janderson@soltra.com>, Paul Patrick < ppatrick@isightpartners.com>, "Jordan, Bret"
< bret.jordan@bluecoat.com>, " cti-cybox@lists.oasis-open.org" < cti-cybox@lists.oasis-open.org>, Terry MacDonald
< terry@soltra.com>
Subject: Re: [cti-cybox] CybOX 3.0: File Object Refactoring
Overall I like the proposal.
I have a few comments:
- For ‘extension_type’, I had a slight bit of confusion upon opening the email that this was the “file extension type” (e.g., exe). If others had the same confusion, maybe updating the field name to something like “metadata_type” or “metadata_class” and/or
updating the description to read along the lines of “Specifies the type (/class) of this metadata extension”. If nobody else had the same confusion, this comment can be disregarded (I just wanted to have a concrete suggestion rather than “it confused me”).
- For MIME type, maybe SHOULD be from the IANA MIME Type registry; MAY be any valid MIME Type production? I believe there are and will be MIME types that are not officially registered with IANA, as the registry permits custom extensions
- For magic number, I’d recommend requiring the hexadecimal representation (vs using the terminology ‘typically…’). To make my suggestion concrete I’ll offer the text: “The magic number [1] for the file represented by this CybOX object. The magic number MUST
be a hex string” (the reference would be to some web site or appendix that lists magic numbers)
- I like requiring mismatch_type when has_mismatch is set to true
Thank you.
-Mark
From: < cti-cybox@lists.oasis-open.org> on behalf of "Kirillov, Ivan A." < ikirillov@mitre.org>
Date: Monday, December 21, 2015 at 3:03 PM
To: Jason Keirstead < Jason.Keirstead@ca.ibm.com>
Cc: "Wunder, John A." < jwunder@mitre.org>, Jerome Athias < athiasjerome@gmail.com>, Patrick Maroney < Pmaroney@specere.org>,
"Barnum, Sean D." < sbarnum@mitre.org>, John Anderson < janderson@soltra.com>, Paul Patrick < ppatrick@isightpartners.com>, "Jordan,
Bret" < bret.jordan@bluecoat.com>, " cti-cybox@lists.oasis-open.org" < cti-cybox@lists.oasis-open.org>, Terry
MacDonald < terry@soltra.com>
Subject: Re: [cti-cybox] CybOX 3.0: File Object Refactoring
Just a heads up that we’ve updated the File Object Refactoring proposal [1] to take into account some of the great points brought up around file metadata and masquerading discussion during our last SC call. Let us know what you think.
FileMetadataExtension
A default extension point for capturing general classes of file metadata. A sub-class of the FileExtension class.
|
Field |
Type |
Multiplicity |
Description |
|
extension_type |
string |
1 |
Specifies the type of this extension; required and MUST be set to 'FileMetadataExtension' |
|
mime_type |
string |
0-1 |
The MIME type name from the IANA media type registry (http://www.iana.org/assignments/media-types/media-types.xhtml)
specified for the file, e.g., "msword". |
|
magic_number |
string |
0-1 |
The particular magic number (typically a hexadecimal constant used to identify a file format) corresponding to the file, if applicable. |
|
has_mismatch |
boolean |
0-1 |
Indicates that there is a mismatch between one or more stated and reported properties of the file. For example, a mismatch between the MIME type of the file its file extension. |
|
mismatch_type |
FileMismatchEnum |
0-N |
Specifies the specific type of file mismatch that was found. This field is required if the has_mismatch property
is set to true. |
FileMismatchEnum
|
Value |
Description |
|
extension/type |
A mismatch between the MIME type reported for the file and its file extension. For example, if the reported MIME type (as captured in the mime_type property)
for the file is 'vnd.microsoft.portable-executable' and the file extension (as captured in the file_name property)
is 'txt'. |
|
magic/extension |
A mismatch between the magic number reported for the file and its file extension. For example, if the reported magic number (as captured in the magic_number property)
for the file is '25504446', indicating a PDF file, and the file extension (as captured in the file_name property)
is 'txt'. |
|
magic/type |
A mismatch between the reported MIME type and magic number for the file. For example, if the reported MIME type (as captured in the mime_type property)
for the file is 'JPEG' and the reported magic number is '424D' (as captured in the magic_number property,
indicating a bitmap file). |
Regards,
Ivan
|