Common Vulnerabilities and Exposures (CVE)

An attacker uses standard SQL injection methods to inject data into the command line for execution. This could be done directly through misuse of directives such as MSSQL_xp_cmdshell or indirectly through injection of data into the database that would be interpreted as shell commands. Sometime later, an unscrupulous backend application (or could be part of the functionality of the same application) fetches the injected data stored in the database and uses this data as command line arguments without performing proper validation. The malicious data escapes that data plane by spawning new commands to be executed on the host.

Typical severity: Very High

Prerequisites: The application does not properly validate data before storing in the database Backend application implicitly trusts the data stored in the database Malicious data is used on the backend as a command line argument

Solutions: Disable MSSQL xp_cmdshell directive on the database Properly validate the data (syntactically and semantically) before writing it to the database. Do not implicitly trust the data stored in the database. Re-validate it prior to usage to make sure that it is safe to use in a given context (e.g. as a command line argument).

An attacker leverages a weakness present in the database access layer code generated with an Object Relational Mapping (ORM) tool or a weakness in the way that a developer used a persistence framework to inject their own SQL commands to be executed against the underlying database. The attack here is similar to plain SQL injection, except that the application does not use JDBC to directly talk to the database, but instead it uses a data access layer generated by an ORM tool or framework (e.g. Hibernate). While most of the time code generated by an ORM tool contains safe access methods that are immune to SQL injection, sometimes either due to some weakness in the generated code or due to the fact that the developer failed to use the generated access methods properly, SQL injection is still possible.

Typical severity: High

Prerequisites: An application uses data access layer generated by an ORM tool or framework An application uses user supplied data in queries executed against the database The separation between data plane and control plane is not ensured, through either developer error or an underlying weakness in the data access layer code generation framework

Solutions: Remember to understand how to use the data access methods generated by the ORM tool / framework properly in a way that would leverage the built-in security mechanisms of the framework Ensure to keep up to date with security relevant updates to the persistence framework used within your application.

An attacker modifies the parameters of the SOAP message that is sent from the service consumer to the service provider to initiate a SQL injection attack. On the service provider side, the SOAP message is parsed and parameters are not properly validated before being used to access a database in a way that does not use parameter binding, thus enabling the attacker to control the structure of the executed SQL query. This pattern describes a SQL injection attack with the delivery mechanism being a SOAP message.

Typical severity: Very High

Prerequisites: SOAP messages are used as a communication mechanism in the system SOAP parameters are not properly validated at the service provider The service provider does not properly utilize parameter binding when building SQL queries

Solutions: Properly validate and sanitize/reject user input at the service provider. Ensure that prepared statements or other mechanism that enables parameter binding is used when accessing the database in a way that would prevent the attackers' supplied data from controlling the structure of the executed query. At the database level, ensure that the database user used by the application in a particular context has the minimum needed privileges to the database that are needed to perform the operation. When possible, run queries against pre-generated views rather than the tables directly.

An attacker is able to leverage access gained to the database to read / write data to the file system, compromise the operating system, create a tunnel for accessing the host machine, and use this access to potentially attack other machines on the same network as the database machine. Traditionally SQL injections attacks are viewed as a way to gain unauthorized read access to the data stored in the database, modify the data in the database, delete the data, etc. However, almost every data base management system (DBMS) system includes facilities that if compromised allow an attacker complete access to the file system, operating system, and full access to the host running the database. The attacker can then use this privileged access to launch subsequent attacks. These facilities include dropping into a command shell, creating user defined functions that can call system level libraries present on the host machine, stored procedures, etc.

Typical severity: Very High

Prerequisites: A vulnerable DBMS is usedA SQL injection exists that gives an attacker access to the database or an attacker has access to the DBMS via other means

Solutions: Design: Follow the defensive programming practices needed to protect an application accessing the database from SQL injection Configuration: Ensure that the DBMS is patched with the latest security patches Design: Ensure that the DBMS login used by the application has the lowest possible level of privileges in the DBMS Design: Ensure that DBMS runs with the lowest possible level of privileges on the host machine and that it runs as a separate user Usage: Do not use the DBMS machine for anything else other than the database Usage: Do not place any trust in the database host on the internal network. Authenticate and validate all network activity originating from the database host. Usage: Use an intrusion detection system to monitor network connections and logs on the database host. Implementation: Remove / disable all unneeded / unused functions of the DBMS system that may allow an attacker to elevate privileges if compromised

This attack exploits target software that constructs SQL statements based on user input. An attacker crafts input strings so that when the target software constructs SQL statements based on the input, the resulting SQL statement performs actions other than those the application intended. SQL Injection results from failure of the application to appropriately validate input.

Typical severity: High

Prerequisites: SQL queries used by the application to store, retrieve or modify data. User-controllable input that is not properly validated by the application as part of SQL queries.

Solutions: Strong input validation - All user-controllable input must be validated and filtered for illegal characters as well as SQL content. Keywords such as UNION, SELECT or INSERT must be filtered in addition to characters such as a single-quote(') or SQL-comments (--) based on the context in which they appear. Use of parameterized queries or stored procedures - Parameterization causes the input to be restricted to certain domains, such as strings or integers, and any input outside such domains is considered invalid and the query fails. Note that SQL Injection is possible even in the presence of stored procedures if the eventual query is constructed dynamically. Use of custom error pages - Attackers can glean information about the nature of queries from descriptive error messages. Input validation must be coupled with customized error pages that inform about an error without disclosing information about the database or application.

Blind SQL Injection results from an insufficient mitigation for SQL Injection. Although suppressing database error messages are considered best practice, the suppression alone is not sufficient to prevent SQL Injection. Blind SQL Injection is a form of SQL Injection that overcomes the lack of error messages. Without the error messages that facilitate SQL Injection, the adversary constructs input strings that probe the target through simple Boolean SQL expressions. The adversary can determine if the syntax and structure of the injection was successful based on whether the query was executed or not. Applied iteratively, the adversary determines how and where the target is vulnerable to SQL Injection.

Typical severity: High

Prerequisites: SQL queries used by the application to store, retrieve or modify data. User-controllable input that is not properly validated by the application as part of SQL queries.

Solutions: Security by Obscurity is not a solution to preventing SQL Injection. Rather than suppress error messages and exceptions, the application must handle them gracefully, returning either a custom error page or redirecting the user to a default page, without revealing any information about the database or the application internals. Strong input validation - All user-controllable input must be validated and filtered for illegal characters as well as SQL content. Keywords such as UNION, SELECT or INSERT must be filtered in addition to characters such as a single-quote(') or SQL-comments (--) based on the context in which they appear.