Avoid Impersonation And The Trustworthy Flag

Solomon Rutzky explains how you can use module signing to avoid the security risks which come with impersonation and setting Trustworthy on:

Admittedly, using Cross-Database Ownership Chaining and/or Impersonation and/or TRUSTWORTHY are quicker and easier to implement than Module Signing. However, the relative simplicity in understanding and implementing these options comes at a cost: the security of your system.

  • Cross-DB Ownership Chaining:
    • security risk (can spoof User / DB-level)
    • db_ddladmin & db_owner users can create objects for other owners
    • Users with CREATE DATABASE permission can create new databases and attach existing databases
  • Impersonation:
    • If IMPERSONATE permission is required:
      • can be used any time
      • No granular control over permissions
    • Cross-DB operations need TRUSTWORTHY ON
    • Need to use ORIGINAL_LOGIN() for Auditing
    • Elevated permissions last until process / sub-process ends or REVERT
  • TRUSTWORTHY:
    • Bigger security risk
      • can also spoof Logins, such as “sa” !
      • If using SQLCLR Assemblies, no per-Assembly control of ability to be marked as either EXTERNAL_ACCESS or UNSAFEall Assemblies are eligible to be marked as either of those elevated permission sets.

The common theme across all three areas is no control, within a Database, over who or what can make use of the feature / option, or when it can be used.

Read the whole thing.

Related Posts

Aggregations And Always Encrypted

Monica Rathbun finds trouble with Always Encrypted: The real challenges started when the client began to test their application code. The first thing we hit was triggers. The table had several insert triggers associated with the columns that were now encrypted. Since the data was now encrypted the insert triggers would fail. Again, we lucked […]

Read More

Storing Credentials For Containers

Andrew Pruski shows how to store a credential using Powershell and pass it into a Docker container: I work with SQL Server in containers pretty much exclusively when testing code and one of my real bug bears is that SQL Server in containers does not support Windows authentication (unless you’re using Windocks). So when I’m working […]

Read More

Leave a Reply

Your email address will not be published. Required fields are marked *

Categories

January 2018
MTWTFSS
« Dec  
1234567
891011121314
15161718192021
22232425262728
293031