> > Is it typical for a masking feature to make no effort to prevent > unmasking? I’m just struggling to see the value of this without such > mechanisms. Otherwise it’s just a default formatter, and we should consider > renaming the feature IMO
I'd say it's a pretty standard feature. There are two parts in the proposal; the CQL functions and the ability to link them to columns. The CQL functions can indeed been seen as a formatter. You can see similar functions for example in MySQL, being what they call "Enterprise Data Masking and De-identification". Its doc says "MySQL provides general-purpose masking functions that mask arbitrary strings, and special-purpose masking functions that mask specific types of values.". As long as I know, MySQL only offers this functions, without being related to any permissions. Documentation is here <https://dev.mysql.com/doc/refman/8.0/en/data-masking-usage.html>. Associating masking functions to columns allows to prevent the accidental leakage of sensitive data by part of users that actually have access to the data. So it can be seen as mandatory formatting, not preventing malicious uses with read permission to force their way into the clear data. You can find disclaimers about it for example in the "Dynamic Data Masking" feature of Azure SQL/SQL server: "The purpose of dynamic data masking is to limit exposure of sensitive data, preventing users who shouldn't have access to the data from viewing it. Dynamic data masking doesn't aim to prevent database users from connecting directly to the database and running exhaustive queries that expose pieces of the sensitive data.". Its doc even has a specific section about this, here <https://docs.microsoft.com/en-us/sql/relational-databases/security/dynamic-data-masking?view=sql-server-ver16#security-note-bypassing-masking-using-inference-or-brute-force-techniques> . As another example, IBM Db2 allows to create what they call masks. I don't see any disclaimer about inferring the clear data, but its documentation says "The application of enabled column masks does not interfere with the operations of other clauses within the statement such as the WHERE, GROUP BY, HAVING, SELECT DISTINCT, or ORDER BY. The rows that are returned in the final result table remain the same, except that the values in the resulting rows might have been masked by the column masks.", so I understand that it's possible to infer the clear values unless one uses additional permissions or security policies. On Wed, 24 Aug 2022 at 09:48, Benjamin Lerer <ble...@apache.org> wrote: > The PCI DSS Standard v4_0 >> <https://docs-prv.pcisecuritystandards.org/PCI%20DSS/Standard/PCI-DSS-v4_0.pdf> >> requires >> that credit card numbers stored on the system must be "rendered >> unreadable", thus this proposal is _NOT_ a good way to protect credit card >> numbers. > > > My point was simply about the fact that Dynamic Data Masking like any > other feature made sense for some scenario but not for others. I apologise > if my example was a bad one. > > Le mer. 24 août 2022 à 10:36, Claude Warren, Jr via dev < > dev@cassandra.apache.org> a écrit : > >> This change appears to be looking at two aspects: >> >> 1. Add metadata to columns >> 2. Add functionality based on the metadata. >> >> If the system had a generic user defined metadata and the ability to >> define filter functions at the point where data are being returned to the >> client it would be possible for users implement this filter, or any other >> filter on the data. >> >> The concept of user defined metadata and filters could be applied to >> other parts of the system as well. For example, if the metadata were >> accessible from UDFs the metadata could be used in low level filters to >> remove rows from queries before they were returned. >> >> >> >> >> On Wed, Aug 24, 2022 at 9:29 AM Claude Warren, Jr <claude.war...@aiven.io> >> wrote: >> >>> The PCI DSS Standard v4_0 >>> <https://docs-prv.pcisecuritystandards.org/PCI%20DSS/Standard/PCI-DSS-v4_0.pdf> >>> requires >>> that credit card numbers stored on the system must be "rendered >>> unreadable", thus this proposal is _NOT_ a good way to protect credit card >>> numbers. In fact, for any critically sensitive data this is not an >>> appropriate solution. However, there seems to be agreement that it is >>> appropriate for obfuscating some data in some queries by some users. >>> >>> >>> >>> On Wed, Aug 24, 2022 at 9:02 AM Benjamin Lerer <b.le...@gmail.com> >>> wrote: >>> >>>> Is it typical for a masking feature to make no effort to prevent >>>>> unmasking? I’m just struggling to see the value of this without such >>>>> mechanisms. Otherwise it’s just a default formatter, and we should >>>>> consider >>>>> renaming the feature IMO >>>> >>>> >>>> The security that Dynamic Data Masking is bringing is related to how >>>> you make use of the feature. It is somehow the same with passwords. If you >>>> use a weak password it does not bring much security. >>>> Masking a field like people's gender is useless because you will be >>>> able to determine its value in one query. On the other hand masking credit >>>> card numbers makes a lot of sense as it will complicate the life of the >>>> person trying to have access to it and the queries needed to reach the >>>> information will leave some clear traces in the audit log. >>>> >>>> Dynamic Data Masking is not a magic bullet. Nevertheless, it is a good >>>> way to protect sensitive data like credit card numbers or passwords. >>>> >>>> >>>> Le mer. 24 août 2022 à 09:40, Benedict <bened...@apache.org> a écrit : >>>> >>>>> Is it typical for a masking feature to make no effort to prevent >>>>> unmasking? I’m just struggling to see the value of this without such >>>>> mechanisms. Otherwise it’s just a default formatter, and we should >>>>> consider >>>>> renaming the feature IMO >>>>> >>>>> On 23 Aug 2022, at 21:27, Andrés de la Peña <adelap...@apache.org> >>>>> wrote: >>>>> >>>>> >>>>> As mentioned in the CEP document, dynamic data masking doesn't try to >>>>> prevent malicious users with SELECT permissions to indirectly guess the >>>>> real value of the masked value. This can easily be done by just trying >>>>> values on the WHERE clause of SELECT queries. DDM would not be a >>>>> replacement for proper column-level permissions. >>>>> >>>>> The data served by the database is usually consumed by applications >>>>> that present this data to end users. These end users are not necessarily >>>>> the users directly connecting to the database. With DDM, it would be easy >>>>> for applications to mask sensitive data that is going to be consumed by >>>>> the >>>>> end users. However, the users directly connecting to the database should >>>>> be >>>>> trusted, provided that they have the right SELECT permissions. >>>>> >>>>> In other words, DDM doesn't directly protect the data, but it eases >>>>> the production of protected data. >>>>> >>>>> Said that, we could later go one step ahead and add a way to prevent >>>>> untrusted users from inferring the masked data. That could be done adding >>>>> a >>>>> new permission required to use certain columns on WHERE clauses, different >>>>> to the current SELECT permission. That would play especially well with >>>>> column-level permissions, which is something that we still have pending. >>>>> >>>>> On Tue, 23 Aug 2022 at 19:13, Aaron Ploetz <aaronplo...@gmail.com> >>>>> wrote: >>>>> >>>>>> Applying this should prevent querying on a field, else you could leak >>>>>>> its contents, surely? >>>>>>> >>>>>> >>>>>> In theory, yes. Although I could see folks doing something like this: >>>>>> >>>>>> SELECT COUNT(*) FROM patients >>>>>> WHERE year_of_birth = 2002 >>>>>> AND date_of_birth >= '2002-04-01' >>>>>> AND date_of_birth < '2002-11-01'; >>>>>> >>>>>> In this case, the rows containing the masked key column(s) could be >>>>>> filtered on without revealing the actual data. But again, that's >>>>>> probably >>>>>> better for a "phase 2" of the implementation. >>>>>> >>>>>> Agreed on not being a queryable field. That would also preclude >>>>>>> secondary indexing, right? >>>>>> >>>>>> >>>>>> Yes, that's my thought as well. >>>>>> >>>>>> On Tue, Aug 23, 2022 at 12:42 PM Derek Chen-Becker < >>>>>> de...@chen-becker.org> wrote: >>>>>> >>>>>>> Agreed on not being a queryable field. That would also preclude >>>>>>> secondary indexing, right? >>>>>>> >>>>>>> On Tue, Aug 23, 2022 at 11:20 AM Benedict <bened...@apache.org> >>>>>>> wrote: >>>>>>> >>>>>>>> Applying this should prevent querying on a field, else you could >>>>>>>> leak its contents, surely? This pretty much prohibits using it in a >>>>>>>> clustering key, and a partition key with the ordered partitioner - but >>>>>>>> probably also a hashed partitioner since we do not use a cryptographic >>>>>>>> hash >>>>>>>> and the hash function is well defined. >>>>>>>> >>>>>>>> We probably also need to ensure that any ALLOW FILTERING queries on >>>>>>>> such a field are disabled. >>>>>>>> >>>>>>>> Plausibly the data could be cryptographically jumbled before using >>>>>>>> it in a primary key component (or permitting filtering), but it is >>>>>>>> probably >>>>>>>> easier and safer to exclude for now… >>>>>>>> >>>>>>>> On 23 Aug 2022, at 18:13, Aaron Ploetz <aaronplo...@gmail.com> >>>>>>>> wrote: >>>>>>>> >>>>>>>> >>>>>>>> Some thoughts on this one: >>>>>>>> >>>>>>>> In a prior job, we'd give app teams access to a single keyspace, >>>>>>>> and two roles: a read-write role and a read-only role. In some cases, >>>>>>>> a >>>>>>>> "privileged" application role was also requested. Depending on the >>>>>>>> requirements, I could see the UNMASK permission being applied to the >>>>>>>> RW or >>>>>>>> privileged roles. But if there's a problem on the table and the >>>>>>>> operators >>>>>>>> go in to investigate, they will likely use a SUPERUSER account, and >>>>>>>> they'll >>>>>>>> see that data. >>>>>>>> >>>>>>>> How hard would it be for SUPERUSERs to *not* automatically get the >>>>>>>> UNMASK permission? >>>>>>>> >>>>>>>> I'll also echo the concerns around masking primary key components. >>>>>>>> It's highly likely that certain personal data properties would be used >>>>>>>> as a >>>>>>>> partition or clustering key (ex: range query for people born within a >>>>>>>> certain timeframe). In addition to the "breaks existing" concern, I'm >>>>>>>> curious about the challenges around getting that to work with the >>>>>>>> current >>>>>>>> primary key implementation. >>>>>>>> >>>>>>>> Does this first implementation only apply to payload (non-key) >>>>>>>> columns? The examples in the CEP currently do not show primary key >>>>>>>> components being masked. >>>>>>>> >>>>>>>> Thanks, >>>>>>>> >>>>>>>> Aaron >>>>>>>> >>>>>>>> >>>>>>>> On Tue, Aug 23, 2022 at 6:44 AM Henrik Ingo < >>>>>>>> henrik.i...@datastax.com> wrote: >>>>>>>> >>>>>>>>> On Tue, Aug 23, 2022 at 1:10 PM Andrés de la Peña < >>>>>>>>> adelap...@apache.org> wrote: >>>>>>>>> >>>>>>>>>> One thought: The way the CEP is currently written, it is only >>>>>>>>>>> possible to mask a column one way. You can only define one masking >>>>>>>>>>> function >>>>>>>>>>> for a column, and since you use the original column name, you could >>>>>>>>>>> only >>>>>>>>>>> return one version of it in the result set, even if you had a way >>>>>>>>>>> to define >>>>>>>>>>> several functions. >>>>>>>>>>> >>>>>>>>>> >>>>>>>>>> Right, it's one single type of mapping per the column, declared >>>>>>>>>> on CREATE/ALTER TABLE statements. Also, users can manually specify >>>>>>>>>> their >>>>>>>>>> own masking function in SELECT statements if they have permissions >>>>>>>>>> for >>>>>>>>>> seeing the clear data. >>>>>>>>>> >>>>>>>>>> For those cases where the data is automatically masked for an >>>>>>>>>> unprivileged user, I don't see the use of including different types >>>>>>>>>> of >>>>>>>>>> masking for the same column into the same result set. Instead, we >>>>>>>>>> might be >>>>>>>>>> interested on having different types of masking associated to >>>>>>>>>> different >>>>>>>>>> roles. We could do so with dedicated CREATE/DROP/LIST MASK >>>>>>>>>> statements, >>>>>>>>>> instead of using the CREATE/ALTER/DESCRIBE TABLE statements. That >>>>>>>>>> CREATE >>>>>>>>>> MASK statement would associate a masking function to a column and >>>>>>>>>> role. >>>>>>>>>> However, I'm not sure we need that type of granularity instead of the >>>>>>>>>> simplicity of attaching the masking to the column declaration. wdyt? >>>>>>>>>> >>>>>>>>>> >>>>>>>>>> >>>>>>>>> My gut feeling likewise is that this adds complexity but little >>>>>>>>> value. >>>>>>>>> >>>>>>>>>> >>>>>>>>>>> >>>>>>>>> >>>>>>>>> -- >>>>>>>>> >>>>>>>>> Henrik Ingo >>>>>>>>> >>>>>>>>> +358 40 569 7354 <358405697354> >>>>>>>>> >>>>>>>>> [image: Visit us online.] <https://www.datastax.com/> [image: >>>>>>>>> Visit us on Twitter.] <https://twitter.com/DataStaxEng> [image: >>>>>>>>> Visit us on YouTube.] >>>>>>>>> <https://urldefense.proofpoint.com/v2/url?u=https-3A__www.youtube.com_channel_UCqA6zOSMpQ55vvguq4Y0jAg&d=DwMFaQ&c=adz96Xi0w1RHqtPMowiL2g&r=IFj3MdIKYLLXIUhYdUGB0cTzTlxyCb7_VUmICBaYilU&m=bmIfaie9O3fWJAu6lESvWj3HajV4VFwgwgVuKmxKZmE&s=16sY48_kvIb7sRQORknZrr3V8iLTfemFKbMVNZhdwgw&e=> >>>>>>>>> [image: Visit my LinkedIn profile.] >>>>>>>>> <https://www.linkedin.com/in/heingo/> >>>>>>>>> >>>>>>>> >>>>>>> >>>>>>> -- >>>>>>> +---------------------------------------------------------------+ >>>>>>> | Derek Chen-Becker | >>>>>>> | GPG Key available at https://keybase.io/dchenbecker and | >>>>>>> | https://pgp.mit.edu/pks/lookup?search=derek%40chen-becker.org | >>>>>>> | Fngrprnt: EB8A 6480 F0A3 C8EB C1E7 7F42 AFC5 AFEE 96E4 6ACC | >>>>>>> +---------------------------------------------------------------+ >>>>>>> >>>>>>>
