CWE-566: Access Control Bypass Through User-Controlled SQL Primary Key
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)
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 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
Description
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.
Implementation
Use a parameterized query AND make sure that the accepted values
conform to the business rules. Construct your SQL statement
accordingly.
Description
