User Controlled Primary Key

ID

csharp.user_controlled_primary_key

Severity

high

Remediation Complexity

medium

Remediation Risk

medium

Remediation Effort

medium

Resource

Misconfiguration

Language

CSharp

Tags

ASVS50:v8.2.1, CWE:566, NIST.SP.800-53, PCI-DSS:6.5.6

Description

This vulnerability arises when an application uses user-supplied input to control primary key values for database queries or operations, which may lead to unauthorized data access or modification.

Rationale

When user input is directly used to build database queries, including primary keys, it can result in unauthorized access or manipulation of protected data.

This problem is particularly dangerous when primary keys are integers or predictable values, as it enables users to perform unintended actions like accessing records that belong to other users, potentially exposing or corrupting sensitive information.

For example, consider this C# code snippet:

String userId = request.getParameter("userId");

PreparedStatement stmt = connection.prepareStatement("select * from invoices where uid=?");
preparedStatement.setInt(1, id); // FLAW

preparedStatement.executeQuery();

In this example, the userId parameter is user controlled, which may allow a user to access data of any user simply by changing the userId value.

Remediation

To mitigate the risks of CWE-566, it’s essential to avoid constructing database queries using user-supplied input directly or allow user input to control database primary key values. Best practices include:

If the SQL query is constructed without relying on user-controlled input, such as through the use of parameterized SQL, attackers cannot access unauthorized records.

When the identifier legitimately comes from the request, authorize it against the caller: check that the record belongs to the authenticated principal, and prefer doing so before the lookup, so an unauthorized identifier never reaches the database.

Whether a given method of your own performs that authorization is project knowledge, not something recoverable from the code, so the rule cannot infer it. If you delegate the check to a helper, declare that helper as a neutralizer in a custom library metadata file (conf.custom/libraries/<technology>/*.yml), naming the argument that carries the identifier and the primary_controlled_key kind:

# schema: library_schema.json
name: acme-authorization
technology: java
modules:
  - name: acme
    classes:
      - name: com.acme.security.AccessGuard
        functions:
          - name: validateUser
            neutralizations:
              - argPos: [0]
                kind: primary_controlled_key

Identifiers validated through the declared helper are then no longer reported. An inline check that is not declared this way stays reported, because nothing in the code distinguishes it from an unrelated comparison.

Some mechanisms do not check a value: they scope where the lookup runs. A wrapper runs a callback for one caller or tenant, an annotation or a guard protects a whole handler, or a call installs the scope for the statements after it. Declare such a mechanism with scopes, naming the forms it takes: wrapper, annotation or install. A lookup that runs inside the region is then not reported:

# schema: library_schema.json
name: acme-tenancy
technology: java
modules:
  - name: acme
    classes:
      - name: com.acme.tenancy.TenantContext
        functions:
          - name: runAs
            neutralizations:
              - kind: primary_controlled_key
                scopes: [ wrapper, install ]

When the application profile names an enforcement point that keeps one caller’s records away from another’s, the same regions are read from it. The forms depend on the kind of enforcement point:

  • An annotation or an interceptor (for example @UseGuards(OwnerGuard) in NestJS) scopes the handler it applies to, or every handler of the type it decorates.

  • A handler call scopes the callback it wraps, and the statements after it in the same function.

A lookup withdrawn this way is kept as an info record with suppressed_by: scoped_context, naming the profile fact and where it was asserted.

Language Wrapper (callback or block) Annotation Install

Java

lambda, try-with-resources

method, class

yes

Python

with, lambda

decorator on function or class

yes

C#

using, lambda, anonymous method

attribute on method or type

yes, including using var

JavaScript / TypeScript

arrow function, function expression

decorator, or a class named in its arguments

yes

Limits of this version:

  • A mechanism installed in another file (a servlet filter or a middleware setting the tenant for every request) does not scope a region the analysis can see.

  • A method reference, or a named function, handed to a wrapper is not a region: its body does not say where it runs.

  • An install inside a condition, a loop or a try covers its own block only. A function defined after an install and run later is not covered.

  • A function handed to an executor from inside a region, and run after the region ends, is still considered covered.

  • Kotlin, Go, PHP and Swift have no scoped regions yet. Ruby has no SAST analysis.

Configuration

The detector has the following configurable parameters:

  • sources, that indicates the source kinds to check.

  • neutralizations, that indicates the neutralization kinds to check.

Unless you need to change the default behavior, you typically do not need to configure this detector.

References

  • CWE-566 : Authorization Bypass Through User-Controlled SQL Primary Key.

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