I want to mask certain data either by obfuscation or addition of a masking character.
Using traditional rpad and lpad plus replacing leading digits all have undesired outputs. SQL Server 2016 has a built in data masking function.
See mockup code:
Select mask(ssn,7,4, 'X') from dual;
input 111-11-1234
output: 111-11-XXXX
None.
Not sure what the "undesired outputs" are using rpad and lpad functions, but you could always create a UDF that gives you the correct reformatting of your string. I believe that this works for what you are looking for:
SELECT RPAD(LEFT($1,7),LENGTH($1),'X') FROM (VALUES ('123-44-5678'));
AFAIK Currently there is no such function in Snowflake to mask data.
But this article explains how to use roles and a mapping table to obfuscate PII data.
Related
How to add leading zeros in ADF data flow from the expression builder
For example – have column with numeric value as “000001” but it is coming as 1 only in SQL DB , if I put in entire value in single quotes it is coming but I need dynamic way of implementation with out hard coding.
I agree with #Larnu's comments that even if we give 00001 to an int type column it will give as 1 only.
So, we have to give those in single quotes ('00001') to use like that or import the incoming data as string instead of int.
As you are using ADF dataflow, if you want to use the 00001, you can generate those using derived column transformation from SQL source. But this depends on your requirement like how your leading 0's varies. So, use according to it.
Sample demo:
concat('0000', toString(id))
Result:
Use that column as per your requirement, after that you can convert it back to the same input by toInteger(id).
I am computing HASH value of each row in a table (for diffing purpose), after implementing the algorithm I am testing the results.
Results are consistent and algorithm somewhat seems to work, but testing it step by step I found a strange result.
The script:
SELECT HASHBYTES('SHA1', (SELECT INNERTBL.VALUT FOR XML RAW)) as KHASH
FROM ACLING AS INNERTBL
Should perform the SHA1 calculation on the table key, but when I perform the same calculation with external tool I get different results:
In fact when I perform SHA1('<row VALUT="A"/>') with external tool (tool here: https://emn178.github.io/online-tools/sha1.html) I get a different result:
So my question is, there is something wrong with my logic or simply SQL Server use some non standard SHA1 "parametrization"? (I have suspect about the use of a, may be standard but particular, padding scheme)
Example in fiddler: https://dbfiddle.uk/?rdbms=sqlserver_2019&fiddle=efa4e0ba11c112f54e36afb5d54d2cce
SELECT HASHBYTES('SHA1','<row VALUT="A"/>'), --- you are testing this
HASHBYTES('SHA1',N'<row VALUT="A"/>') -- ..but for xml returns Nvarchar
It is important to remember that you get the same result only if the string are binary the same. For example if the two strings uses different characterset they will have different HASH value. For more details please check thsi out https://security.stackexchange.com/questions/18290/is-sha-1-hash-always-the-same
I have this piece of code in Oracle which I need to convert into SQL Server to get the same behavior. I have used the REPLACE function. It seems to be working but I just wanted to make sure.
REGEXP_REPLACE(
phonenumber,
'([[:digit:]]{3})([[:digit:]]{3})([[:digit:]]{4})',
'(\1)\2-\3'
) phonenumber
As Martin said in his answer, SQL Server does not have built-in RegEx functionality (and while it has not been suggested here, just to be clear: no, the [...] wildcard of LIKE and PATINDEX is not RegEx). If your data has little to no variation then yes, you can use some combination of T-SQL functions: REPLACE, SUBSTRING, LEFT, RIGHT, CHARINDEX, PATINDEX, FORMATMESSAGE, CONCAT, and maybe one or two others.
However, if the data / input has even a moderate level of complexity, then the built-in T-SQL functions will be at best be cumbersome, and at worst useless. In such cases it's possible to do actual RegEx via SQLCLR (as long as you aren't using Azure SQL Database Single DB or SQL Server 2017+ via AWS RDS), which is (restricted) .NET code running within SQL Server. You can either code your own / find examples here on S.O. or elsewhere, or try a pre-done library such as the one I created, SQL# (SQLsharp), the Free version of which contains several RegEx functions. Please note that SQLCLR, being .NET, is not a POSIX-based RegEx, and hence does not use POSIX character classes (meaning: you will need to use \d for "digits" instead of [:digit:]).
The level of complexity needed in this particular situation is unclear as the example code in the question implies that the data is simple and uniform (i.e. 1112223333) but the example data shown in a comment on the question appears to indicate that there might be dashes and/or spaces in the data (i.e. xxx- xxx xxxx).
If the data truly is uniform, then stick with the pure T-SQL solution provided by #MartinSmith. But, if the data is of sufficient complexity, then please consider the RegEx example below, using a SQLCLR function found in the Free version of my SQL# library (as mentioned earlier), that easily handles the 3 variations of input data and more:
SELECT SQL#.RegEx_Replace4k(tmp.phone,
N'\(?(\d{3})\)?[ .-]*(\d{3})[ .-]*(\d{4})', N'($1)$2-$3',
-1, -- count (-1 == unlimited)
1, -- start at
N'') -- RegEx options
FROM (VALUES (N'8885551212'),
(N'123- 456 7890'),
(N'(777) 555- 4653')
) tmp([phone]);
returns:
(888)555-1212
(123)456-7890
(777)555-4653
The RegEx pattern allows for:
0 or 1 (
3 decimal digits
0 or 1 )
0 or more of , ., or -
3 decimal digits
0 or more of , ., or -
4 decimal digits
NOTE
It was mentioned that the newer Language Extensions might be a better choice than SQLCLR. Language Extensions allow calling R / Python / Java code, hosted outside of SQL Server, via the sp_execute_external_script stored procedure. As the Tutorial: Search for a string using regular expressions (regex) in Java page shows, external scripts are actually not a good choice for many / most uses of RegEx in SQL Server. The main problems are:
Unlike with SQLCLR, the only interface for external scripts is a stored procedure. This means that you can't use any of that functionality inline in a query (SELECT, WHERE, etc).
With external scripts, you pass in the query, work on the results in the external language, and pass back a static result set. This means that compiled code now has to be more specialized (i.e. tightly-coupled) to the particular usage. Changing how the query uses RegEx and/or what columns are returned now requires editing, compiling, testing, and deploying the R / Python / Java code in addition to (and coordinated with!) the T-SQL changes.
I'm sure external scripts are absolutely wonderful, and a better choice than SQLCLR, in certain scenarios. But they certainly do not lend themselves well to the highly varied, and often ad hoc, nature of how RegEx is used (like many / most other functions).
SQL Server does not have native regex support. You would need to use CLR (or as #Lukasz Szozda points out in the comments one of the newer Language Extensions) .
If I have understood the regex correctly though it matches strings of 10 digits and assigns the first 3 to group 1, second 3 to group 2, and last 4 to group 3 and then uses the back references in the expression (\1)\2-\3
You can use built in string functions to do this as below
SELECT CASE
WHEN phonenumber LIKE REPLICATE('[0-9]', 10)
THEN FORMATMESSAGE('(%s)%s-%s',
LEFT(phonenumber, 3),
SUBSTRING(phonenumber, 4, 3),
RIGHT(phonenumber, 4))
ELSE phonenumber
END
You can write SQL function using CLR, that will wrap standard dotnet regex. I have wrote this and you can use it there. It will look this:
DECLARE #SourceText NVARCHAR(MAX) = N'My first line <br /> My second line';
DECLARE #RegexPattern NVARCHAR(MAX) = N'([<]br\s*/[>])';
DECLARE #Replacement NVARCHAR(MAX) = N''
DECLARE #IsCaseSensitive BIT = 0;
SELECT regex.Replace(#SourceText, #RegexPattern, #Replacement, #IsCaseSensitive);
I have a table of allowed formats that I need to be able to lookup based on a string. Some example formats are:
^.^.testdomain.com
^.testdomain.com
^qwerty^.testdomain.com
I need to return one or more matching rows based on a sample input of:
device.name.testdomain.com would return the first and second format
johnqwertysmith.testdomain.com would return all the formats
Unfortunately the character '^' is fixed as the wildcard, this is a constraint I can't change.
I was hoping that perhaps regex could save me here, maybe using the format as the pattern and comparing it to the input. Regex is not something I have used much in the past so I'm not really sure of its capabilities. Failing that, is there any other way of performing this lookup?
Like this:
SELECT *
FROM yourTable
WHERE #INPUT LIKE REPLACE(yourTable.savedFormat, '^', '%')
This won't allow you to leverage any indexs on your savedFormat column, but I suspect thats hopeless anyway for these requirements.
I have recently taken on a project in which I need to integrate with PHP/SQL Server. I am looking for the quickest and easiest function to prevent SQL injection on SQL Server as I prefer MySQL and do not anticipate many more SQL Server related projects.
Is this function sufficient?
$someVal = mssql_escape($_POST['someVal']);
$query = "INSERT INTO tblName SET field = $someVal";
mssql_execute($query);
function mssql_escape($str) {
return str_replace("'", "''", $str);
}
If not, what additional steps should I take?
EDIT:
I am running on a Linux server - sqlsrv_query() only works if your hosting environment is windows
The best option: do not use SQL statements that get concatenated together - use parametrized queries.
E.g. do not create something like
string stmt = "INSERT INTO dbo.MyTable(field1,field2) VALUES(" + value1 + ", " + value2 + ")"
or something like that and then try to "sanitize" it by replacing single quotes or something - you'll never catch everything, someone will always find a way around your "safe guarding".
Instead, use:
string stmt = "INSERT INTO dbo.MyTable(field1,field2) VALUES(#value1, #value2)";
and then set the parameter values before executing this INSERT statement. This is really the only reliable way to avoid SQL injection - use it!
UPDATE: how to use parametrized queries from PHP - I found something here - does that help at all?
$tsql = "INSERT INTO DateTimeTable (myDate, myTime,
myDateTimeOffset, myDatetime2)
VALUES (?, ?, ?, ?)";
$params = array(
date("Y-m-d"), // Current date in Y-m-d format.
"15:30:41.987", // Time as a string.
date("c"), // Current date in ISO 8601 format.
date("Y-m-d H:i:s.u") // Current date and time.
);
$stmt = sqlsrv_query($conn, $tsql, $params);
So it seems you can't use "named" parameters like #value1, #value2, but instead you just use question marks ? for each parameter, and you basically just create a parameter array which you then pass into the query.
This article Accessing SQL Server Databases with PHP might also help - it has a similar sample of how to insert data using the parametrized queries.
UPDATE: after you've revealed that you're on Linux, this approach doesn't work anymore. Instead, you need to use an alternate library in PHP to call a database - something like PDO.
PDO should work both on any *nix type operating system, and against all sorts of databases, including SQL Server, and it supports parametrized queries, too:
$db = new PDO('your-connection-string-here');
$stmt = $db->prepare("SELECT priv FROM testUsers WHERE username=:username AND password=:password");
$stmt->bindParam(':username', $user);
$stmt->bindParam(':password', $pass);
$stmt->execute();
No, it's not sufficient. To my knowledge, string replacement can never really be sufficient in general (on any platform).
To prevent SQL injection, all queries need to be parameterized - either as parameterized queries or as stored procedures with parameters.
In these cases, the database calling library (i.e. ADO.NET and SQL Command) sends the parameters separately from the query and the server applies them, which eliminates the ability for the actual SQL to be altered in any way. This has numerous benefits besides injection, which include code page issues and date conversion issues - for that matter any conversions to string can be problematic if the server does not expect them done the way the client does them.
I partially disagree with other posters. If you run all your parameters through a function that double the quotes, this should prevent any possible injection attack. Actually in practice the more frequent problem is not deliberate sabotague but queries that break because a value legitimately includes a single quote, like a customer named "O'Hara" or a comment field of "Don't call Sally before 9:00". Anyway, I do escapes like this all the time and have never had a problem.
One caveat: On some database engines, there could be other dangerous characters besides a single quote. The only example I know is Postgres, where the backslash is magic. In this case your escape function must also double backslashes. Check the documentation.
I have nothing against using prepared statements, and for simple cases, where the only thing that changes is the value of the parameter, they are an excellent solution. But I routinely find that I have to build queries in pieces based on conditions in the program, like if parameter X is not null then not only do I need to add it to the where clause but I also need an additional join to get to the value I really need to test. Prepared statements can't handle this. You could, of course, build the SQL in pieces, turn it into a prepared statement, and then supply the parameters. But this is just a pain for no clear gain.
These days I mostly code in Java that allows functions to be overloaded, that is, have multiple implementations depending on the type of the passed in parameter. So I routine write a set of functions that I normally name simply "q" for "quote", that return the given type, suitably quoted. For strings, it doubles any quote marks, then slaps quote marks around the whole thing. For integers it just returns the string representation of the integer. For dates it converts to the JDBC (Java SQL) standard date format, which the driver is then supposed to convert to whatever is needed for the specific database being used. Etc. (On my current project I even included array as a passed in type, which I convert to a format suitable for use in an IN clause.) Then every time I want to include a field in a SQL statement, I just write "q(x)". As this is slapping quotes on when necessary, I don't need the extra string manipulation to put on quotes, so it's probably just as easy as not doing the escape.
For example, vulnerable way:
String myquery="select name from customer where customercode='"+custcode+"'";
Safe way:
String myquery="select name from customer where customercode="+q(custcode);
The right way is not particularly more to type than the wrong way, so it's easy to get in a good habit.
String replacement to escape quotes IS sufficient to prevent SQL injection attack vectors.
This only applies to SQL Server when QUOTED_IDENTIFIER is ON, and when you don't do something stoopid to your escaped string, such as truncating it or translating your Unicode string to an 8-bit string after escaping. In particular, you need to make sure QUOTED_IDENTIFIER is set to ON. Usually that's the default, but it may depend on the library you are using in PHP to access MSSQL.
Parameterization is a best practice, but there is nothing inherently insecure about escaping quotes to prevent SQL injection, with due care.
The rel issue with escaping strings is not the efficacy of the replacement, it is the potential for forgetting to do the replacement every time.
That said, your code escapes the value, but does not wrap the value in quotes. You need something like this instead:
function mssql_escape($str) {
return "N'" + str_replace("'", "''", $str) + "'";
}
The N above allows you to pass higher Unicode characters. If that's not a concern (i.e., your text fields are varchar rather than nvarchar), you can remove the N.
Now, if you do this, there are some caveats:
You need to make DAMNED SURE you call mssql_escape for every string value. And therein lies the rub.
Dates and GUID values also need escaping in the same manner.
You should validate numeric values, or at least escape them as well using the same function (MSSQL will cast the string to the appropriate numeric type).
Again, like others have said, parameterized queries are safer--not because escaping quotes doesn't work (it does except as noted above), but because it's easier to visually make sure you didn't forget to escape something.