CWE-566: Authorization Bypass Through User-Controlled SQL Primary Key
Authorization 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:
Data enters a program from an untrusted source.
The data is used to specify the value of a primary key in a SQL query.
The untrusted source does not have the permissions to be able to access all rows in the associated table.
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);
The problem is that the developer has not considered 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.
Description
