Access Control Bypass Through User-Controlled SQL Primary Key
Weakness ID: 566 (Weakness Variant)Status: Incomplete
+ Description

Description Summary

The software uses a database table that includes records that should not be accessible to an actor, but it executes a SQL statement with a primary key that can be controlled by that actor.

Extended Description

When a user can set a primary key to any value, then the user can modify the key to point to unauthorized records.

Database access control errors occur when:

  • 1. Data enters a program from an untrusted source.

  • 2. The data is used to specify the value of a primary key in a SQL query.

  • 3. The untrusted source does not have the permissions to be able to access all rows in the associated table.

+ Time of Introduction
  • Architecture and Design
  • Implementation
+ Demonstrative Examples

Example 1

The following code uses a parameterized statement, which escapes metacharacters and prevents SQL injection vulnerabilities, to construct and execute a SQL query that searches for an invoice matching the specified identifier [1]. The identifier is selected from a list of all invoices associated with the current authenticated user.

(Bad Code)
Example Language: C# 
...
conn = new SqlConnection(_ConnectionString);
conn.Open();
int16 id = System.Convert.ToInt16(invoiceID.Text);
SqlCommand query = new SqlCommand( "SELECT * FROM invoices WHERE id = @id", conn);
query.Parameters.AddWithValue("@id", id);
SqlDataReader objReader = objCommand.ExecuteReader();
...

The problem is that the developer has failed to consider all of the possible values of id. Although the interface generates a list of invoice identifiers that belong to the current user, an attacker can bypass this interface to request any desired invoice. Because the code in this example does not check to ensure that the user has permission to access the requested invoice, it will display any invoice, even if it does not belong to the current user.

+ Potential Mitigations

Phase: Implementation

Assume all input is malicious. Use a standard input validation mechanism to validate all input for length, type, syntax, and business rules before accepting the data. Use an "accept known good" validation strategy.

Phase: Implementation

Use a parameterized query AND make sure that the accepted values conform to the business rules. Construct your SQL statement accordingly.

+ Relationships
NatureTypeIDNameView(s) this relationship pertains toView(s)
ChildOfWeakness BaseWeakness Base639Access Control Bypass Through User-Controlled Key
Development Concepts (primary)699
Research Concepts (primary)1000
+ Content History
Submissions
Submission DateSubmitterOrganizationSource
Anonymous Tool Vendor (under NDA)Externally Mined
Modifications
Modification DateModifierOrganizationSource
2008-07-01Eric DalciCigitalExternal
updated Potential Mitigations, Time of Introduction
2008-09-08CWE Content TeamMITREInternal
updated Relationships, Other Notes, Taxonomy Mappings
2009-07-27CWE Content TeamMITREInternal
updated Demonstrative Examples, Description, Other Notes, Potential Mitigations, Taxonomy Mappings
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